EFFECT OF SELECTED FREEZING METHODS AND SELECTED ADDITIVES ON THE QUALITY CHARACTERISTICS OF FROZEN SLICED BANANAS Thesis for the Degree of M .. S. MICHIGAN STATE UNIVERSITY ANNE INS-CHUNG CHEN 1971 urn-3“ g; . I, BINDING BY am & suns 800K mm m n. W LIBRARY BINDERS II ”unevenlmlfl'fil ABSTRACT EFFECT OF SELECTED FREEZING METHODS AND SELECTED ADDITIVES ON THE QUALITY CHARACTERISTICS OF FROZEN SLICED BANANAS by Anne Ing-Chung Chen This investigation was initiated to determine the effect of freezing methods in combination with syrup concentration on the quality character- istics of banana slices. The study also investigated the effect of CaCl2 on the textural qualities of sliced bananas and the effect of an ascorbic acid/citric acid mixture (ACM) in maintaining color of IQF banana slices. Sensory evaluations, objective measurements and chemical tests were used to evaluate the three replications of each variable of banana slices and the data were statistically analyzed. Sensory evaluation of banana slices indicated that the visually- judged texture ("visual texture"), color, mouth feel, flavor and clarity of syrup for fresh banana slices scored significantly higher than either frozen or frozen-stored banana slices. The color of banana slices in syrup scored significantly higher than that of IQF slices while the visual texture and clarity of syrup for slices in 40% syrups were scored higher than that of slices in 20% syrup. é.ices. s;ares f Anne Ing-Chung Chen The Hunter color-difference meter was used to determine the light- ness (L), redness (aL) and yellowness (bL) of banana slices. Fresh slices were lighter and more yellow than frozen or frozen-stored banana slices. Both L and bL values correlated significantly with sensory scores for color. The frozen-stored banana slices were significantly redder than either fresh or frozen slices and negatively correlated with sensory scores for color. The Allo-Kramer shear press used to determine the texture of banana slices indicated that fresh banana slices were firmer than frozen or frozen-stored slices. The IQF slices were firmer than the slices packed in syrups. There were significant correlations between shear press measurements and both visual texture and mouth feel as evaluated by the taste panel. The analyses for total ascorbic acid retention showed that both frozen and frozen-stored banana slices had a higher content than fresh banana slices. The IQF slices with the regular amount of ACM in the syrup contained less total ascorbic acid than the other variables. EFFECT OF SELECTED FREEZING METHODS AND SELECTED ADDITIVES ON THE QUALITY CHARACTERISTICS or FROZEN SLICED BANANAS BY Anne lug-Chung Chen A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Science and Human Nutrition 1971 .5 Sing her tance ACKNOWLEDGEMENTS The author is greatly indebted to Dr. Kaye Funk who provided contin- uing advice, guidance and assistance throughout this investigation. To her, the author expresses heartfelt gratitude and appreciation. Sincere gratitude is expressed to Dr. Mary Ellen Zabik for her assis- tance, advice and support throughout the past two years of graduate study. Special thanks are given to Dr. Theodore Wishnetsky for his advice and guidance in this study. Grateful acknowledgements are extended to Mrs. Martha Davis, Miss Elizabeth Hough, Mrs. Beth Roderick, Mrs. Waldina Smith, Miss Charlotte Thompson and Miss Margaret Wayman for their faithful atten- dance on the taste panel. ii Met Fre TABLE OF CONTENTS INTRODUCTION ..... .. ............. . ............................... REVIEW OF LITERATURE Composition of Plant Tissue ..... . ....................... ..... Physical composition ... ............. . ..................... Chemical composition ................. Tannins ........ Enzymes 00.00.000.000 Vitamin content ... 00.00.0000... 00.00.... Methods of Processing Bananas .. .............................. Canning ... Dehydration ................................ . .............. Freezing . Freezing Injury of Plant Tissue ... OOOOOOCCOOOO. Physical changes ....... .00.... O O '0 O ..... O 0000000000 CO... .0000... O O. O O O 0 COO... ......OOOOOOO... Effect of freezing temperature ..... Chemical changes .... Vitamins Color Flavor 00...... .0000. 0'. O. O O. .......... O. O OOOOOOOOOOOOOOOOOO O 0000000 .0. O. 0.. O ......... 0.. O 0.. .0... O... COCOOOOOO ..... 0.0... O 0000000000000 0.0... O O O. .00... O I .0... .90... O .0. ...... O. O ........ iii 10 13 13 l3 14 15 15 l7 l7 17 19 19 RES’ Use of Additives ................................... .......... Additives to deter textural changes ....................... Additives to deter color changes .......................... Ascorbic acid .... ..... .............. ............ . ...... Sugar ......................................... ..... .... EXPERIMENTAL PROCEDURE ....... ......................... . ..... ... Ingredient Procurement ........................ ........ ....... Syrup Formulas..................... ........................... Preparation of Banana Slices ............................ ..... Bananas frozen in syrup ............. ...................... IQF banana slices ........................ ....... .......... Fresh, unfrozen banana slices .... ......................... Defrosting Procedures ................................ ........ Sensory Evaluations ........ ........... . ............. . ........ Objective Measurements ......... ..... . ....... . ..... .. ....... .. Color measurements ........ ................................ Texture measurements ... .......... ........ .............. ... Chemical Measurements ... ............... .. ..... . ...... . ....... Ascorbic acid determinations .......... ................ .... RESULTS AND DISCUSSION .......................................... Sensory Evaluation of Banana slices ......... ................. iv Page 20 21 21 22 23 24 24 26 26 27 27 27 28 29 29 29 30 30 31 33 33 m LIE: APPE: Visual texture ........... Mouth feel ...... .. . Flavor .................................................... Clarity of syrup ......... Objective Measurements ....................................... Color ... 00.0.00.........OOOOOOOOOOOOOOO. The L or lightness values .............................. The aL or redness values ............ The bL or yellowness values .......... Alla-Kramer shear press measurements ....... Moisture content ........... Ascorbic acid SUMMARY AND CONCLUSIONS ........ LITERATURE CITED APPENDIX ...... ... OOOOOOOOOOOOOOOOOOO 4O 4O 45 47 47 47 50 52 54 57 59 64 69 74 LIST OF TABLES Table Page 1. Composition of banana, per 100 g of edible portion ........ 7 2. Ascorbic acid content of bananas as determined by various investigators OI0.000.0000000000000000...00.000000000000000 11 3. Formulas used in preparation of syrups .................... 25 4. Analyses of variance for determining the effect of treat- ments and variance on the sensory evaluations of sliced bananas 0.00.I.0O'OOO'OOOCOOIUOOOOOCOIOO0.007.000.0000...OO. 34 5. Averages, standard deviations and statistical analyses for sensory evaluations of visual texture of fresh, frozen and frozen-'Btored banana Slices o a o o o a o o o o o o o a a ccccc 36 6. Averages, standard deviations and statistical analyses for sensory evaluations of color of fresh, frozen and frozen-stored banana slices ............................... 38 7. Averages, standard deviations and statistical analyses for sensory evaluations of mouth feel of fresh, frozen and frozen-stored banana slices ........................... 41 8. Averages, standard deviations and statistical analyses for sensory evaluations of flavor of fresh, frozen and frozen-stored banana Slices '00.0000...OOOCO'OOOO'OO'CO'OOO 42 9. Averages, standard deviations and statistical analyses for sensory evaluations of clarity of syrup of fresh, frozen and frozen-stored banana slices .................... 46 10. Analyses of variance of Hunter colorédifference meter values and Alla-Kramer shear press measurements of fresh, frozen and frozen-stored banana slices .................... 48 11. Averages, standard deviations and statistical analyses for L values of fresh, frozen and frozen-stored banana slices 000....0.000.000.00000.00'COOO'OOO'OOOOOOOOOCOOO0.00 49 vi I3. 15. 17. I9. 20. Table 12. 13. 14. 15. 16. 17. 18. 19. 20. Page Averages, standard deviations and statistical analyses for aL values of fresh, frozen and frozen-stored banana Slices 0.000.000.0000.....OOOOOOOOOOCOOOOOOOOO0.00.0.00...O 51 Averages, standard deviations and statistical analyses for bL values of fresh, frozen and frozen-stored banana slices C.0.0000000'OOOOOOOCOOOOCOOOOOOOO'OCOOOOOOO0.0.0.... 53 Averages, standard deviations and statistical analyses for shear press measurements of fresh, frozen and frozen- Btored banana Slices COO00.000.0.00.0000.00000000000000COOO 55 Averages, standard deviations and statistical analyses for moisture content of fresh, frozen and frozen-stored banana Slices 00......0.00.00.COOOCOOOOOOOOOCCOOOOOC’OOO.... 58 Analyses of variance for determining the effect of treat- ments and variables on the ascorbic acid content of banan8811ces 0.0..COO00000000.....OOOOOOCOO'OOOO‘OOOOOO'0. 6o Averages, standard deviations and statistical analyses for ascorbic acid content of fresh, frozen and frozen- atored banana Slices 000.000......OOOOOOOOOOOOOCOOOOOOCO0.0 62 Averages for five panelists of three replications of sensory evaluations of the quality characteristics of fresh, frozen and frozen-stored banana slices ............. 78 Values for three replications of Hunter color-difference and Alla-Kramer shear press measurements of color and texture, respectively, of fresh, frozen and frozen-stored banana slices ............................................. 79 Values for ascorbic acid content and moisture content of fresh, frozen and frozen-stored banana slices .......... 8O vii '71 (1'3 r. Figure LIST OF FIGURES Page Instructions to taste panel members for evaluating fro- zen BliCEd bananas OOOOOOOOO'OOOOOOOOOOOOO000.000.0000.000. 75 Score sheet used for banana slices frozen in syrup ........ 76 Score sheet used for IQF banana slices ............... ..... 77 viii year. tiOn . natiOi are p‘ Consu; baflan losse. sUCCe; while fruit in Con thESe reCOmJI Gnadag IN TRODUCTION Bananas are one of the best known fruits throughout the world. Pro- duction of the extremely perishable fruit is characterized by rapid growth and quick financial returns on capital outlay. Economic losses result when bananas are not consumed within a short time after harvest (Simmonds, 1966). Total banana production is estimated to be about 20 million tons per year. Most countries with climatic conditions suited for banana produc- tion export part of their crop. From Taiwan, bananas entering into inter- national trade, are sold to Japan (Simmonds, 1966). However, more bananas are produced during the two growing seasons in Taiwan than are traded or consumedlocally resulting in economic losses. By preservation of the bananas the consumption period would be extended thus averting economic losses. Attempts to satisfactorily freeze bananas have met with partial 8l-lccess in that bananas may be frozen for ice cream or bakery trade. while very limited data are available, inherent problems in freezing the fruit are textural changes, browning and loss of flavor. Use of sucrose in combination with ascorbic acid reportedly is helpful in retarding t[lese changes (Von Loesecke, 1949). A 407. syrup or less has been reCommended for maximum quality retention (Meyer, 1964). However, GL1adagni (1969) suggested consumers will have to accept the frozen 1 [0 3f Us HEQCE Slice 10 u1Pa fruit with less than an ideal texture. Calcium chloride (CaClz) has been added to tomatoes during the can- ning process to avert tissue breakdown. The essential reaction appears to be the formation of calcium pectate by interaction of the calcium ions with pectic acid (Loconti gt 31,, 1941). The effect of CaClz on banana slices has not been investigated. Conflicting reports appear in the literature on the ascorbic acid content of bananas (Miller EE.§£°: 1945; Von Loesecke, 1949). In a re- cent study, Wenkam _E‘al. (1965) reported the ascorbic acid content of bananas was 6 mg/100 g of fruit. The effect of freezing on the ascorbic acid content of bananas has not been investigated. The primary purpose of this study was to investigate the effect of freezing method and subsequent storage as well as sucrose concentration in combination with ascorbic acid on the quality characteristics and the ascorbic acid content of frozen sliced bananas. To study the effect of, freezing method, sliced bananas were frozen in syrup and individually quick frozen (IQF) after dipping in 40% syrup containing two levels of ascorbic acid. For bananas frozen in syrup, sucrose concentrations of 20 and 40% were used, each containing one level of ascorbic acid. A secondary purpose of this study was to investigate the feasibility of using Ca012 to improve the textural quality of frozen banana slices. Hence, CaClz was added to syrups containing 20 and 40% sucrose before sliced bananas were frozen in the mixture. These banana slices were compared with those frozen in syrups of the same concentration with no added CaClz. ... ...: 5" SD To determine the effect of the freezing and/or thawing process per g3, the quality characteristics of banana slices were investigated prior to and after two to three weeks of frozen storage. The effect of a three-month storage period was also determined. compo Plant Will REVIEW OF LITERATURE Composition of Plant Tissue Plant parts used as food are composed of tissues which in turn are composed of many different types of cells, each of which may be peculiar to a specific tissue. Cellular contents vary greatly among varieties of plant tissues. The physical and chemical composition of plant tissue will be discussed in general and then Specifically as related to bananas. Physical composition Plant tissue is composed of living cells capable of undergoing meta- bolic reactions after harvest. The chief type of cell in the edible por- tion of most fruits is the parenchyma cell. The thin, cellulose walls of parenchyma cells in the young plant may be separated by air spaces or held together by pectic cementing substances. As the plant ages, the cell walls may increase in thickness and the nature of the cementing substan- ces may change (Meyer, 1960). The protoplasm of parenchyma cells contains many different molecules, forming either a viscous fluid or a gel. The protoplasm is differentia- ted into various cell parts such as the nucleus, cytoplasm, plastids and vacuoles. The nucleus directs the activity of the cell while the 4 cyc Pia men tive type nume of c ized pres Vide OCCU: morp} fmit Studi [EPOr cytoplasm, an undifferentiated part of the protoplasm, surrounds the nu- cleus and forms a rather thin layer within the cell wall (Griswold, 1962). Plastids, contained in the cytoplasm, may be chloroplasts or green pig- ments, chromoplasts or pigments other than green, and/or leucoplasts which produce and store starch. Vacuoles, often referred to as cell sap, are made up of droplets of solutions with strands of cytoplasm around them (Meyer, 1960). In addition to parenchyma cells, conducting, supporting and protec- tive cells are also present in plant tissue. Conducting cells of two types, xylem and phloem, are composed of long tubes through which food is distributed to the plant. Supporting cells, although not generally numerous in plants desirable for food, are long pointed cells with walls of cellulose and lignin or pectic substances. Protective cells or special- ized parenchyma cells that secrete cutin or contain suberin, are closely pressed together and are usually quite tough. The protective cells pro- vide the plant with minute valves through which exchange of gases can occur; however, the coating of cutin or suberin is insoluble in water. Slocum (1933), as cited by Von Loesecke (1949), has detailed the morphology of the banana with particular emphasis on the skin of the fruit. In another treatise, as cited by Von Loesecke (1949), Wolfson studied the morphology of the banana fruit or pulp. According to his report, the cells of the center of the green banana fruit are long and boxlike in shape containing in addition to the cytoplasm and nuclei, numerous starch grains. The banana pulp contains few or no intercell- ular spaces and the cells adhere firmly to one another. As the fruit ripens, the starch tends to disappear. Tissues of the outer portion out 5011] :au: Chen eral pres cose ripen fIUiI hOIS, (Gris The f amoun '-’ anfli1 petty of the pulp show cells of different shapes, held together by pectic sub- stances. Latex tubes, as found in banana skins, are also present in the pulp outlining the margin of the individual carpels. The watery fluid found in the latex tubes is white and milky in appearance. It possesses a pro- nounced astringent taste and will turn brown in the presence of air be- cause of the tannins present (Von Loesecke, 1949). Chemical composition Fruits vary greatly in chemical composition; however, they are gen- erally high in water and relatively low in protein. Carbohydrates are present as cellulose, pectic substances, sugars such as fructose, glu- cose and sucrose, and starch, although the starch tends to disappear on ripening. The vitamin and mineral content is specific to the kind of fruit (Meyer, 1960; Griswold, 1962). Organic acids, aldehydes, alco- hols, esters, tannins and similar compounds are also present in fruits (Griswold, 1962). Data on the composition of ripe banana pulp are presented in Table l. The fruit is composed mainly of water and carbohydrates and has negligible amounts of protein and fat. Tannins The darkening reaction on the exposure of banana tissue to air is a result of oxidation of phenolic substances. Tannins are phenolics with molecules large enough to complex with and precipitate proteins, a pro- Perty responsible for the astringent flavor imparted to many fruits. .5533 9.3208 5 52m 02!. 3 25.5.- 2. 3 veg-Ia :5 .3589303 «on .6380 ...—gel .238 9.03 nasal-“E300 on «15 03-33 ..---- .. 0 a .3... .....o 851.3. ... .... .... ... 2...... ...... ... .2. ..." ... ...: N .. ...... ....” ... 8.8 v... ... .. 3. 8.5 38...... u .2 .... ... a: ... z... ... ...... ...v ... n .2. .. ... .... ... 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As indicated above, tannins are present in the latex tubes of banana skins and fruit. Tannins have been reported as diminishing as the banana ripens. Bar- nell _£_§l. (1945) reported the tannin fraction of the green fruit dimin- ished to about one-fifth of its value when the fruit ripened as studied by diastase inactivation. In contradiction, Harris _£.§l. (1937) stated that the total amount of tannins remained constant during ripening; however, their state changed to an insoluble, inert "vegetative tannate". Barnell g£_gl. (1945) studied the phenolic compounds in bananas. The compounds, leucoanthocyanin, leucodelphinidin, and leucocyanidin, were identified as present in the banana fruit. The compound, 3,4-dihydroxyphenylethylamine, is also present abun- dantly in the skin of bananas but relatively sparse in the pulp (Simmonds, 1966). This compound is the principal substrate of banana polyphenoloxi- dase and thus responsible for the blackening of damaged fruit (Griffiths, 1959). Other substances, 5-hydroxytryptamine, norepinephrine and tyramine, have been detected in banana fruit (Udenfriend _£‘_l., 1959). There is little information regarding their behavior during ripening but S-hydroxy- tryptamine appears to be present in fairly constant amounts in the banana pulp and in increasing amounts in the skin. Enzymes. Studies on the enzyme content of bananas have been reviewed by Von Loesecke (1949). Onslow (1920) made a systematic investigation of many fruits and classified them into two groups, 1) those containing cate- chol substances and oxygenase and 2) those lacking in these two substances. According to her report, bananas belong to the first group. However, more [10 ME str Its tio 0xL of more bEe; this Phes tiOn recent investigations have shown that peroxidase and catalase are always present in both classifications while oxygenase is absent in the second classification (Braverman, 1963). More recently, the name oxygenase is no longer used; instead, phenolase, polyphenolase and polyphenol oxidase are applied. Onslow (1920) reported the oxygenase, as present in both the skin and the banana fruit, catalyzes the oxidation of catechol. In addition, the oxygenase of the skin activated the oxidation of certain aromatic compounds. Phenol oxidases catalyze the aerobic oxidation of certain phenolic sub- strates to quinones and cause the browning of plant tissues (Palmer,1963). Its effect on quality has been concentrated on color changes and oxida- tion of Vitamin C. Joslyn gt _1. (1951) stated that not only the phenol oxidase, but the cytochrome oxidase was also the primary browning agent of fruit. Yasunobu (1959), as cited by Palmer (1963) stated that phenol oxi- dases catalyze the oxidation of a wide variety of substrates, but each individual enzyme tends to catalyze the oxidation of one particular phenol more readily than others. Polyphenoloxidase with optimum pH 7, which has been shown to occur in the pulp and peel of the banana fruit, follows this general pattern. Palmer (1963) reported that dopamine (3,4-dihydroxy- phenylethylamine) is the only significant substrate in the browning reac- tion of the banana fruit. Peroxidase has been widely used as an index of enzyme activity in plant tissue because of its high resistance to thermal inactivation (Aylward g£.§l., 1969). This enzyme catalyzes the oxidation of certain phenolic or aromatic amine compounds to form dark colored polymers. Balls g£_al. 10 (1935) indicated that peroxidase was responsible for darkening of injured apple tissue. Ponting gt a1. (1948), however, demonstrated that peroxi- dase catalyzed darkening of apple tissue was responsible for only a small portion of the color changes. In addition, peroxidase has been recognized as the off-flavor causing enzyme (Aylward gt 31., 1969). Vitamin content In a review of the vitamin content of bananas, Simmonds (1966) cited literature showing the following vitamins were contained in the fruit; B- carotene, thiamine, riboflavin, pyridoxine, niacin, pantothenic acid, inos- itol, folic acid and ascorbic acid. Banana varieties show considerable variance in vitamin content. For example, Rudra (1936) found that the pulp of the plantain contained nine times as much ascorbic acid as the pulp of the banana. Miller 35 31. (1945) stated that the two most widely grown varieties of bananas, Bluefield and Chinese, were only fair sources of Vitamin A, contained negligible amounts of thiamine and were poor sources of ascor- bic acid. These workers also reported the cooking banana, Maiamaoli, was a good source of Vitamin A, a poor source of thiamine and a fair source of ascorbic acid. While Harris 35 _l. (1939) stated that bananas were a good source of Vitamin C, they also reported that the fruit lost some of its ascorbic acid by exposure to air during the preparation pro- cess of slicing. Bananas have been investigated by many workers for ascorbic acid con- tent and different results have been reported. Table 2 summarizes the findings of these investigators. Whenever possible, the variety of 11 Table 2. --Ascorbic acid content of bananas as determined by various investigators. < Investigator Ascorbic Acid mg/ g of Pulp Givens et a1. b 0.05 Eddy and Kelloggc 0. 10 Eddyd 0. 05 Dalldorfe o. 05 Birch et a1. f 0. 15 Levertong (Honduras grown) O. 073 Harris and Polandh 0. 10 Harris and Poland1 (Gros Michel) 0. 053 -0. 111 Thorntonj (Gros Michel) O. 10 Munser (Gigante, Spanish) 0. 068 - 0. 071 Rose 0. 085-0. 12 aAdapted from Von Loesecke, H. W. (1949). bGivens, M. H., Cluggage, H. B., and Van Horne, E.G., Proc. Soc. Exptl. Biol. Med., 18, 140 (1921). cEddy, W. H., and Kellogg, M., Am. J. Public Health, 17, 27 (1927). dEddy, w. H., Am. J. Public Health, 19, 1309 (1929). eDalldorf, c... J. Exptl. Med., 53, 289 (1931). fBirch, T. W., Harris, L. J., and Ray, 5. N., Biochem. J., 27, 590 (1933). gLeverton, R. M., Food Research, 2, 59 (1937). hHarris, P. L., and Poland, G. L., ibid., 2, 311 (1937). ‘Harris, P. L., and Poland, G. L., ibid., 4, 317 (1939). JThornton, N. C., Contrib. Boyce Thompson Inst, 13, 201 (1943). kMunsell, H. E., Food Research, 10, 42 (1945). 1Rose, M. 8., Foundations of Nutrition, Macmillan, New York, 1933. 12 banana is indicated. Thornton (1943) showed that ascorbic acid increased slightly at the time of early development of the yellow color of bananas. The ascorbic acid content fell gradually with complete yellowing to 10 to 12 mg/lOOg of pulp. According to his report, the ascorbic acid content remained at this level until more than 50% of the peel had turned brown during normal ripening and the pulp had softened. Further reduction in the ascorbic acid content took place with continued ripening. Harris gt 31. (1939) found that slight chilling had no deleterious effect on the ascorbic acid content of the fruit. However, severe chill— ing as indicated by blackened skin, resulted in losses of over 50% of the ascorbic acid. In addition to the vitamin content, bananas have been reported to be a fair source of calcium and iron. In addition, they contain copper, iodine, manganese, zinc, cobalt, potassium, magnesium, sodium and phos- phorus (Bogert, 1942). 13 Methods of Processing Bananas Bananas have been processed by canning, dehydration and freezing. In addition, numerous speciality products such as powder, flout, jam and paste have been tried; however, bananas lose much of their flavor in development of these items and these various products have not been readily acceptable. Canning According to Von Loesecke (1949), bananas should be processed under pressure because of the high pH of the fruit; however, processing under pressure ruins the flavor and significantly alters the texture of the bananas. The author suggested combining banana slices with citrus juice or with citrus fruits such as grapefruit, tangerines or oranges to alter the pH for processing. Simmonds (1966) pointed out that canning is not a satisfactory pro- cessing method for bananas because of their pH. However, United Fruit Company have in pilot production, canned bananas in sucrose syrup (Lawler, 1967). Lynch _£._1. (1959) outlined a procedure for canning bananas. The banana slices were packed with a 300 Brix syrup containing 0.5% citric acid and 0.2% CaC12. Quality of the bananas was not reported. Dehydration Banana flour has been manufactured from unripe fruit and banana pow- der produced from ripe fruit. In addition, dehydrated banana slices have been processed (Brekke t 1., 1967). Q5 ~.\~ 14 Generally, banana powder is made by passing the peeled fruit through a meat chopper to obtain a slurry which may be dried on a steam-heated drum dryer. Double drums are preferable for the processing and the dis- tance between the drums must be carefully adjusted to variations in the ripeness of the fruit to avoid excessive crumbling. The product, as it comes from the drums, is in the form of flakes which may or may not be ground. The flavor of drum-dried flakes or powder is that of cooked bananas; hence, the product provides a high quality ingredient in cooked or baked products. Brekke £5 31. (1967) reported that banana slices were dehydrated by air-blast drying, drum drying and freeze drying. Sulfur dioxide treat- ment prior to drying was used for comparison. They found the treatment with $02 improved the product in all of these drying methods. Upon recon- stitution, the freeze-dried slices more nearly resembled fresh banana slices than did slices dried by the other methods. Stability of the pro- ducts showed the air-blast dried banana slices the least stable, drum- dried better and freeze-dried the best. Freezing Meyer (1964) outlined a procedure for home freezing of mashed bananas. Working rapidly, banana slices were mashed, combined with a mixture of sugar and ascorbic acid-citric acid powder, packaged and then frozen. The. author recommended defrosting only until soft enough to combine with other ingredients used in preparation of a food item. Procedures for freezing sliced bananas have also been outlined (Harding, 1951). Von Loesecke (1949) stated that unlike many other fruits, bananas t"! 2i du pa ail dUG am: 15 do not seem to be well adapted for preservation by freezing. The defrosted product becomes a soggy mass, rapidly darkens and there is a loss of flavor. Darkening and flavor loss are probably due to enzymatic action which is apparent even during frozen storage. He suggested the use of ascorbic acid in combination with citric acid to retard the darkening and loss of flavor. The addition of citric acid probably changes the pH, renders the enzymes inactive and permits the ascorbic acid to act as an antioxidant. Sucrose is used in combination with ascorbic acid and citric acid and is helpful in retarding deteriorative changes. Freezing Injury of Plant Tissue Any food may be considered as a system. The specific arrangement of constituents and phases in a food system is responsible for well-defined sensory, physical and chemical properties. Any alteration in the arrange- ment of components will lead to changes in the characteristics of the entire system. Physical changes For frozen pieces of fruit, the most serious consequence of the free- zing process is the adverse effect on textural and structural properties (Guadagni, 1969). According to Fennema _£Mal. (1964), damage which occurs during freezing is caused by the transformation of water to ice. The ex- pansion of water as it freezes, coupled with the contraction of most non- aqueous constituents of the fruit, results in localized stress which pro- duces physical damage in cellular materials. Materials containing large amounts of water and few intercellular air Spaces will show a net l6 expansion upon freezing and hence, a greater likelihood of damage (Mac- Arthur, 1948; Dietrich 35 51., 1957; Borgstrom, 1961; Joslyn gt $1., 1952). Flabbiness of thawed young stems may be due to lack of complete re- absorption of water which migrated from cells to intercellular spaces. Polysaccharides of cell walls are highly hydrOphilic and water is abundant in cell walls. Ice crystals may be formed and can easily distort well organized cell wall fibrils and thawed walls may consequently lack rigid- ity (Fennema gt g1,, 1964). According to Reeve (1970), certain aspects of freezing damage and its effects on textural qualities are closely related to the structural differ- entiation of specialized tissues. Fibrous tissues, such as vascular bun- dles or other thick walled tissues, are resistant to freezing damage. Localized differential rate of freezing often result in torn parenchyma cell walls and the development of large voids. But they seldom produce a comparable damage in the compact, thickawalled tissues. The abnormal softness of mushiness is developed with the freezing and thawing of paren- chyma tissue. According to Levitt (1960), freezing injury is due in all cases to breaks in protoplasmic bonds as a result of local stresses arising on ice formation in tissue. The stresses arise by direct pressure due to ice formation, by ice formed within the cells, and by collapse and subsequent expansion of cells due to dehydration accompanying extracellular ice for- mation and rehydration on thawing. Rapid thawing has been claimed to reduce opportunities for product damage. During thawing, however, temperatures rise very rapidly to the melting plateau and remain near the freezing point for a long period of 17 time. According to Fennema 35 El. (1964), recrystallization may occur during this time. Effect of freezing temperature. Very rapid freezing has been claimed to improve the texture of frozen peaches and strawberries (Guadagni, 1969). However, Lee _£‘a1. (1949) reported that strawberries, raspberries and sliced peaches packed in syrup showed few differences in vitamin content, appearance, flavor and texture whether frozen very slowly, very rapidly or at intermediate rates. According to their report, the retention of these quality factors during a 6-mo storage period at -18°C, recrystallization had occurred to the extent that all samples contained crystals of essentially the same size. Ice crystals generally have a tendency to enlarge during frozen stor- age and early stages of thawing. If thawed following minimal storage, rapidly frozen samples will generally exhibit less loss of fluid than slowly frozen samples (Fennema gt El-: 1964). Chemical changes Because metabolic processes continue during storage of fruits, deter- iorative changes will depend to a large extent upon the temperature (Fennema _£.El': 1964). Some typical chemical changes occurring during frozen storage relate to vitamin content (Cain, 1967), color and flavor characteristics (Dietrich.g£_§1,, 1960; Boggs 35 31., 1960). Vitamins. Cain (1967) reported that freezing per 32 does not injure vitamins. Rather, it is the mishandling both before and after freezing which is responsible for vitamin losses. Particularly destructive to vitamins, is alternation of freezing and thawing during storage. In per vit min tha r) ‘12 :3 inc aSC Can f0:- in aSC 18 addition, packaging characteristics such as light transmission, oxygen permeability and water vapor permeability, have effects on the loss of vitamins in foods. According to Jansen (1969), the loss of and change in different vita- mins during the preparation, freezing and storage of foods varies greatly. For example, the Vitamin C content of vegetables is quite labile whereas that in cans of frozen orange juice concentrate is stable. Cain (1967), in a review of the effect of processing on water-soluble vitamins, reported that the retention of ascorbic acid, thiamine and pan- tothenic acid was little affected by the time but very much influenced by the temperature of storage. For example, Davis (1956) reported that losses up to 95% of the initial ascorbic acid could be expected in frozen vegetables held for 12 mo. at ~120C. At a storage temperature of -18°C the loss was about 25% while at temperatures of -29°C, the loss was about 5%. According to Cain (1967) the time of storage was a much more signifi- cant factor than temperature of storage in the retention of niacin. Also, increasing the storage temperature had less effect on riboflavin than on ascorbic acid or thiamine retention. Lee _£‘§1. (1949) reported that very slow, very rapid and intermed- iate rates of freezing did not result in marked differences in vitamin content and in retention of vitamins during a 6-mo storage period at -18°C for strawberries, raspberries and sliced peaches. Harris £5 El. (1939) stated that slight chilling of bananas resulted in no loss of ascorbic acid. However, a loss of more than 50% of the ascorbic acid occurred in severely chilled bananas. 8C a!» e D1 2‘ ta. fle in: brt Slj fla «0U 19 92125. Jansen (1969) stated that the most important and noticeable change in sliced frozen peaches was browning due to the enzyme, polyphenol- oxidase, which catalyzed the reaction of phenolic compounds to quinones which in turn became brown polymers. Polyphenoloxidase color reactions occurred during frozen storage of apple slices, bananas and avocados, according to Jansen (1969). According to Cain (1967) oxygen permeable packaging materials contri- bute to browning because oxygen.is requisite for this reaction. Guadagni gt _1. (1957) stated that significant color changes in frozen peach slices appeared in approximately one-third of the time that detectable flavor chan- ges occurred when fruits were stored at -9 to -4°C. Flavor. According to Jansen (1969), texture, appearance, odor and taste contribute to flavor; hence, any changes from the desirable or nor- mal would constitute off-flavor. Guadagni g£_§1. (1957) stated that the flavor of severely browned peach slices was altered as a result of brown- ing and the flavor change varied directly with the degree of intensity of browning. They reported there was an essentially linear relationship be- tween quality scores assigned by a trained panel and number of brown slices per package. One type of flavor change in frozen vegetables is termed "delay" off- flavor or a haylike flavor. Kohman _£l_1., as cited by Jansen (1969), found the bruising of some vegetables produced this "delay" off-flavor. Strawberries have been reported to have "off-flavors" when they were frozen slowly (Heiss, 1942) although, freezing rates generally have more effects on texture of fruits rather than flavor (Heiss, 1942). 20 Use of Additives The most serious defect present in fruits which have been frozen is; a change in the textural characteristics. Light-colored fruits, such as apples and bananas, are subject to undesirable color changes caused by enzymatic browning during and after thawing (Guadagni, 1969). The use of additives to prevent textural or color changes will be discuased. Additives to deter textural changes Calcium salts have been used to prevent softening of canned fruits and vegetables, especially tomatoes. According to Loconti gg‘gl. (1941), the essential reaction is the formation of calcium pectate in the tissues by the reaction of calcium ions with pectic acid. The formed salts sup- port the tissues of the tomatoes against softening and disintegration during processing. Siegel (1939) reported that calcium chloride, being a salt of a strong acid and highly dissociated produces a more satisfactory "calcium effect" than other calcium salts of weak acids. Kertesz 35.31. (1938) indicated three methods of applying calcium; 1) dipping the peeled fruit into a calcium chloride solution prior to canning, 2) adding calcium chloride £2; £3 to the can before sealing, and 3) using combination salt tablets which contain calcium chloride. According to Powers $5.31. (1961), one of the problems connected with the use of calcium compounds is that some of them such as calcium chloride, when used above certain levels impart a bitter or salty taste to the product. In addition to firming plant tissue, calcium chloride has been reported 21 to offer a new means for helping to control heat damage during drying and non-enzymatic browning during storage at warm temperatures for products such as dehydrated potatoes (Simon 55‘31., 1955). Additives to deter color changes Guadagni (1969) stated that the most commonly used method to minimize color changes during freezing and thawing of fruit is by packing them in sucrose syrup containing ascorbic acid.’ With this method, the factors involved in preventing color changes are the amount of ascorbic acid and the extent of oxygen exclusion effected by the syrup. Ascorbic acid. Ascorbic acid, both L- and d-forms, has been intro- duced for the control of enzymatic and autooxidative discoloration. The L-form is widely used in preventing the discoloration of fruit during freezing storage. It acts primarily by reducing the oxygen present in or surrounding the fruit tissues and in maintaining a reducing condition in the tissues of the fruit (Esselen gg‘gl., 1949; DuBois, 1949). Accor- ding to Jansen (1969), ascorbic acid functions not only by reducing the oxygen surrounding the fruit tissues but also by reversing the browning reaction at the quinone stage. Von Loesecke (1949) indicated that color changes in frozen fruit could be retarded by use of ascorbic acid in combination with citric acid. The citric acid probably functioned to change the pH, thus rendering enzymes inactive and permitting the ascorbic acid to act as an antioxidant. 22 Sgggg. Sugar and sugar solutions are used in freezing of fruit to exclude direct contact of the fruit tissue with oxygen (Joslyn.g£.§1., 1948). Thus, sugar and sugar solutions help preserve color and in addi- tion, act as an enhancer of the natural fruit flavor (Guadagni, 1969). According to Joslyn g£_gl. (1951), the sugar solutions inhibit dis- coloration by reducing the concentration of dissolved oxygen, hence, reducing the rate of oxygen diffusion into fruit tissue. Joslyn (1949) also reported that concentrated sugar solutions exert an inhibiting effect on fruit oxidases. Quin (1929) as cited by Joslyn EE.§l' (1951), reported when solutions were present in the same concentration, the retarding effect of sucrose was greater than that of glycerol or dextrose. Tressler (1943) indicated that in addition to protecting the fruit from air and retarding enzyme actions, sugar solutions acted to reduce evaporation of the more volatile esters and other compounds responsible for the characteristic aroma and flavor of the fruit. He also reported that sucrose solutions penetrated into the fruit during freezing, storage and thawing thus improving the flavor of sour fruit. EXPERIMENTAL PROCEDURE This study was designed to determine the effects of freezing on the quality characteristics of bananas. For this purpose, sliced bananas were frozen in sucrose syrup concentrations of 20 and 40% and individually quick frozen (IQF) after dipping in 40% sucrose syrup. All syrups contained an ascorbic aéid/citric acid mixture (ACM). A second purpose of this study was to investigate the effect of a firming agent, calcium chloride (CaClZ), on the textural qualities of bananas. Therefore, 0.2% CaClZ was added to both the 20 and 40% sugar syrups and the sliced bananas in these syrups were compared with those in syrups containing no CaClZ. To investigate the effectiveness of the ACM in maintaining quality during freezing and subsequent storage by the IQF method, two levels of ACM.were used. One of the levels was the same as that used for sliced bananas frozen in syrup while the second level contained three times as much ACM. Hence, the six variables included in this study were as follows: 1. 20% syrup + 1.0% ACM 2. 20% syrup + 1.0% ACM + 0.2% CaCl2 3. 40% syrup + 1.0%.ACM 4. 40% syrup + 1.0% ACM + 0.2% CaClz 5. IQF (40% syrup + 1.0% ACM) 6. IQF (40% syrup + 3.0% ACM) 23 24 Three replications of each variable were subjected to sensory evalua- tion and objective and chemical measurements in the fresh unfrozen state, after frozen storage of two to three weeks, and after frozen storage of three months. Each replication consisted of three identical containers of bananas. Ingredient Procurement Chiquita brand, Honduras grown bananas were procured through a local wholesaler. All bananas were sorted according to color. They were then held at room temperature (21°C) until the desired ripeness, as indicated by color, was attained and then they were processed. Granulated sugar and reagent grade CaC121 were each obtained from common lots. Bottles of an ascorbic acid/citric acid mixture (ACM)2 were thoroughly blended to insure a common lot. Syrup Formulas Syrups for the six variables of this study were prepared according to the formulas given in Table 3. The weight of each ingredient was cal- culated using the following formula based on specific gravities of the 20 and 40% syrups.3 Grams = Volume (m1) X Sp Gr of Syrup Conc X % Ingredient lMallinckrodt Chemical Works, St. Louis. 2Product of Chas. Pfizer & Co., Inc., New York, 10017. Contains 15% citric acid, 7% ascorbic acid, 7% sucrose, 1% sodium silico aluminate. 3 Handbook of Chemistry and Physics, 4lst ed., 1959- 1960, Chemical Rubber Publishing Co., 2310 Superior Ave., N. E., Cleveland. 25 . . Haw .mH . rmm .PH NHUGU mma .HmN mmo .rm mmo .bm mmo .bm mwfi .mw mm.— .mw 20¢ mmwm mem mmmm mmwm mmfih mmfib Umzflmfig £0me Nwmm Nwmm wwwm wam vwba van.“ mmofiufim .. ... v m m . 33:83... “.3...an > .9333... > .mGH 95mm 5 couonm on??? «o :oapmuwmosm 5 com: mmfisauom ..- .m 3an 26 A Toledo torsion balance, S-kg capacity, was used for weighing sugar and water. ACM and Ca012 were weighed to the nearest 0.000 g using a Mettler balance, Model H-lS. To prepare syrups, appropriate weighed quantities of sucrose and water were heated over medium heat in stainless steel pans with constant stirring until all sucrose was dissolved. Syrups were cooled for approx- imately 24 hr in a 5°C refrigerator before the appropriate amounts of Ca012 and/or ACM‘were added. Concentrations of syrups were checked using an Abbe refractometer. Preparation of Banana Slices Bananas of the same degree of ripeness were peeled and cut into 3/8- in slices using a household-type, wire butter cutter. Banana slices were put into distilled water in a stainless steel bowl for about 2 min until the quantity needed for each container had been cut. All banana slices were frozen and stored at -23°C until subsequent evaluation. Banana slices frozen in syrup One hundred and eighty grams of banana slices were drained on a stain- less steel screen for approximately 10 sec before they were put into coded, plastic freezer containers and covered with 250 ml of syrup. Waxed paper was crumpled and placed on top of the bananas to hold the slices beneath the surface of the syrup. 27 IQF banana slices Thirty six slices of bananas at room temperature were dipped into 250 ml of the specified, chilled syrup with no stirring for approximately 2 min. Most of the slices sunk in the syrup but approximately 8 to 11% floated at the surface. To allow for air circulation, slices were then arranged in a single layer on a perforated sheet (approximately 4 holes/inz) of waxed paper which covered a 12" x 12" wire cake cooling rack. After freezing for an hour, the banana slices were placed in polyethylene bags 0.75 mil in thickness and closed with metal twist closures. The closed bags were put into coded, paraffin waxed quart freezer cartons and stored until subsequent evaluation. Fresh, unfrozen banana slices Immediately prior to sensory evaluations and objective and chemical measurements, three replications of fresh bananas from the common lot and of the same degree of ripeness were prepared as outlined above with the following exceptions. Rather than freezing and subsequent thawing, these banana slices in syrup were chilled at 5°C prior to evaluation. In addi- tion, objective and chemical meaSurements were conducted on fresh banana slices without the added syrup. Defrosting Procedures Sensory evaluations showed a preference for defrosted banana slices containing a few ice crystals. Hence, defrosting times which permitted a few ice crystals to remain in the slices were established through pre- liminary investigations. 28 For sensory evaluations and objective measurements, banana slices fro- zen in 20% syrups were defrosted for approximately 8 l/2 hr in a 5°C refrig- erator, banana slices frozen in 40% syrups were defrosted for approximately 7 hr while IQF banana slices were defrosted in single layer for approxi- mately 2 hr in individual glass dishes covered with Saran wrap. The mini- mal amount of liquid which drained from the slices during thawing was left in the dishes. For chemical measurements, all variables of banana slices frozen in syrup were defrosted for approximately 15 hr while IQF slices, still in their original freezing bag, were defrosted for approximately 2 hr. The liquid that drained from the IQF slices during thawing was left in the bag. Sensory Evaluations A six-member taste panel was utilized to determine the visually- judged texture ("visual texture"), color, mouth feel and flavor of banana slices as well as clarity of syrup of slices frozen in syrup. All attributes were scored on S-point rating scales and any additional comments from judgments were noted. The rating scales appear in the Appendix along with instructions given to the taste panel members. For evaluation, all samples were coded with random numbers. Nine test sessions were used with six samples presented at each session. Banana slices were served in glass dishes placed on white trays. Conditions of lighting and environment were constant for each session. 29 Objective Measurements Objective tests were used to evaluate color and texture of banana slices prior to freezing, after freezing and after frozen storage of three months. Fresh banana slices with no added syrup were tested for compari- son. Color measurements Color of banana slices was measured using a Hunter color-difference meter, model D—25. The instrument was standardized with a yellow tile (L, 82.8; -3.5; bL, 26.2) covered with an optical lens in prepara- 8L, tion for determination of L (lightness), a greenness or redness) and L< bL (blueness or yellowness) values of the banana slices. Positive values for aL measurements indicated redness while positive values for bL measurements indicated yellowness according to the instructions for the instrument. Slices were randomly taken from the container of banana slices and placed in a single layer in a 88 x 14 mm petri dish and covered with an Optical lens. The covered dish was then placed on a white tile under the viewing area and the reading was recorded. A second reading was obtained after rotating the covered dish one—quarter of a turn. The two readings were then averaged. Texture measurements Texture of banana slices was measured using the standard shear-com- pression cell of an Allo-Kramer shear press, model SP-lZ, equipped with 30 an electronic recorder, model EZEZ. The lOO-lb proving ring, 100% range, 25 lb of pressure and a 30-sec downstroke were used for this measurement. Banana slices were poured into a screen and drained for 10 sec before weighing to the nearest gram. A 100-g sample was randomly selected and placed in the lower assembly of the cell in a random manner and values for texture were recorded as the upper assembly sheared through the ban- ana slices. Both sections of the cell assembly were rinsed with tap water between each evaluation. Texture of the bananas was expressed as pounds force per gram using the following formula. Maximum graph reading x 32232 x Ring 100 100 Sample weight (g) Chemical Measurements The ascorbic acid content was determined for samples prior to freez- ing, after freezing, and after frozen storage. Fresh banana slices with- out added syrup and syrups of the six variables were also analyzed for comparison. For accurate calculations of ascorbic acid content, moisture determinations were also conducted. Moisture determinations Following the procedure outlined by A.0.A.C. (1960) the moisture con- tent of the bananas was determined. Defrosted banana slices were drained on a screen for 10 min before two slices were randomly selected for this analysis. The two banana slices were mashed, divided approximately equally, and duplicate samples ranging in weight from 2.3 to 5.0 g were weighed 31 into dried, tared aluminum moisture dishes, using a Mettler balance, model H-lS. The samples were dried for 6 hrs at 70°C under a vacuum of 28 in. Hg, using a Labline Vacuum Oven Cat. No. 3615. The duplicate determina- tions were then averaged. Ascorbic acid determinations The modified osazone method described by Schwartz gt El. (1955) was used to determine total ascorbic acid. After draining on a metal screen for 10 min and standing at room temperature for about 5 min while samples for moisture analyses were weighed, a 25 g sample of banana was blended for 2 min with 350 m1 of 0.57. oxalic acid and 10 g filter aid1 in a Waring blender set at low Speed. After filtering through Whatman No. 4 filter paper, a 2 ml aliquot of the filtrate was pipetted into each of three 30 ml test tubes. One drop of 2,6-dichlorophenolindophenol was added to each tube. After shaking each tube, 2 ml of 1% thiourea was added to each tube and then 1 ml of 2% 2,4-dinitropheny1 hydrazine was added to two of each set of three test tubes. All samples including the blank containing no 2,4-dinitropheny1 hydrazine were incubated at 37°C for 3 hr. After incubation, 5 ml of HCl-H3PO4 (3:2) were added to each sample along with 1 ml of 2% 2,4-dinitrophenyl hydrazine to the blank. Percentage of transmittance of each sample was determined after sha- king each tube, using a Beckman DB-G Grating Spectrophotometer set at a wave length of 540 nm. Duplicate readings were averaged for each variable 1Hiflo celite, Johns-Manville products. 32 and the amount of total ascorbic acid, expressed as mg ascorbic acid/100g sample (wet weight), was calculated using values from a standard curve which plotted percentage transmittance for known solutions of 0.002 mg, 0.004 mg, 0.008 mg, 0.012 mg, 0.016 mg ascorbic acid analyzed using the procedure as outlined. The formula follows. Mg Ascorbic Acid/100g sample (wet weight) = Curve value x 2 x Total volume RESULTS AND DISCUSSION This study was designed to determine the effects of freezing on the quality characteristics of banana slices frozen in 20 and 40% sucrose syrup and individually quick frozen (IQF) after dipping in 40% sucrose syrup. All syrups contained an ascorbic acid/citric acid mixture (ACM). This study also investigated the effect of calcium chloride (CaClZ) on the textural qualities of frozen bananas; therefore, CaC12 was added to 20 and 40% syrups and the bananas in these syrups were compared with those in syrups containing no CaClZ. The effectiveness of ACM in main- taining quality during freezing and subsequent storage by the IQF method was determined by using two levels of the mixture. Three replications of each variable were subjected to sensory evaluation and objective and chem- ical measurements in the fresh unfrozen state, after freezing and after frozen storage of three months. Sensory Evaluation of Banana Slices A six-member taste panel evaluated the banana slices for visual tex- ture, color, mouth feel and flavor as well as clarity of syrup for approx- imate samples using a S-point rating scale. Treatment and variable aver- ages for the panelists of three replications appear in the Appendix, Table 17. Mean squares obtained through analyses of variance are shown in Table 4. 33 34 5:38.63 do 3:: 28 .35 H “a «amoafiflmi mm mm #308 o: .o vm 3N6 m: .o mmmd mzd mm 5535 “5&2. .o : 3&3 .o 3&3 .m .5236 flag .H S Hfloabsm mmmd m m: .o :56 "imam.“ mmmd oH :oflomumfi: in: .H m :o .0 m3 .o *amov .m lawman .H m. o3m€m> *vwoov .H m *vwmow .m *uwvom .mm imam .2 “5.3% .w m aaogwouH oucmm “mom @55on Mo 5330 8366on noting £502 uoaou 1363/ Eomooum mocmflwxw mo mo mo moumsvm moooMmQ mmumsvm mooummm oopsom smog smog .mmumcwn voonm mo mcoflmgmaro .Comaom 65 no moan—Some» cam mucogmofi mo ”roots on... wfififiuoaoc, no.“ 6053.28, Ho $63.34.. .v 3nt 35 Visual texture Averages, standard deviations and statistical analyses for sensory evaluations of visual texture are shown in Table 5. When analyzed for differences between treatments, fresh banana slices had significantly higher (P<:0.01) averages of 4.3 for visual texture than either frozen or frozen—stored banana slices, both of which had average scores of 3.1. Because there was no significant difference between visual texture scores for frozen and frozen-stored bananas, the data suggest it was the freezing and/or thawing process per §g_which affected textural qualities thus sup- porting the conclusions of Guadagni (1969). All variables in 40% syrup (Variables 3, 4, 5, 6) scored signifi- cantly higher (P4£0.0l) in visual texture than variables in 20% syrup (Variables l, 2). Average scores for banana slices in 40% syrup with and without CaC12 and IQF slices in syrups containing the regular amount and increased ACleere 3.9, 3.5, 3.6 and 4.0, respectively while scores averaged 2.9 and 3.0 for banana slices in 20% syrup with and without CaClZ, respectively. Comments of the panelists indicated that the banana slices in 20% syrup showed sloughing and appeared soft. The IQF slices dipped in syrup containing increased ACM (Variable 6) were judged significantly higher (P<10.05) in visual texture with an aver- age score of 4.0 than IQF slices dipped in syrup containing the regular amount of ACM (Variable 5) with an average score of 3.6, which, according to the panelists, appeared soft and resembled baked fruit. The addition of CaClZ (Variables 2, 4) did not significantly affect the scores for visual texture. 36 .393 .cwoaamv Sonatas miemoflamfi Ho: mam. 6:3 68% 65 .3 62003695 mmsdflwm ... .o a. H .m So in H .m w .o a ma swarm; Hamgmmse Ndama Hamlin H.323. 20¢. Nm+mGH .m N531” Scams mafia mGH ..u. me m.w.m.mvH.m Tongs. H.525 HionH. NHUmo+s$ .H. H.oHH.m mags. means .soH. .m avod Teams mega Soaps NHUmo+som .m Sofia foams. HioHoH. son .H o . . m a. mo o VnH Ho o VnH @8on 88am swarm namnoum . moEmEm> mooemoEHcmHm am «we HmoHHmHHSm H EH .H. .moofim madman nougmuaosonm cam Gouonm .nmoum .Ho 9258» Adam? mo maofiwfiwtro .Comaom .HoH mmmfiwnm Hmofimfiflm and 9.85325 vamvzflm .mmwmuozw..- .m 3an 37 Color The data of this investigation as presented in Table 6 showed that fresh banana slices were scored significantly higher (P<10.01) in color than either frozen or frozen-stored slices thus suggesting reactions occurring during the freezing and/or thawing process were responsible for color changes. Fresh banana slices had an average color score of 4.6, thus indicating the banana slices were creamy yellow with very little sur- face browning. Frozen and frozen-stored banana slices averaged 3.2 and 2.9, respectively, indicating surface browning on the slices which was most evident in the placenta. The high standard deviations indicate con- siderable variance among the judges in their evaluations of color. When analyzed for variance between variables, the data showed banana slices in syrup (Variables l, 2, 3, 4) were significantly lighter (P410.01) in color than IQF slices (Variables 5, 6). Average scores of 3.8, 3.9, 3.9 and 4.1 were recorded for slices in 20% syrup with and without CaClz and 40% syrup with and without CaClz, respectively, while IQF banana slices in syrups with regular and an increased amount of ACM averaged 2.5 and 3.1, respectively, for color scores. Guadagni (1969) stated the use of syrups containing ascorbic acid to pack fruits for freezing was bene- ficial in preventing color changes. The syrup functioned to exclude oxy- gen while the ascorbic acid maintained a reducing condition in the tissues of the fruit (Esselen gt 31., 1949, DuBois, 1949). Apparently, the concentration of the syrup was not an important factor in preventing color changes because no significant differences existed between Variables l, 2 and Variables 3, 4 which contained 20 and 40% 38 .29: .HHmoHHHHDV #:23ch .anemonHemHm you was on: 65mm m5 .3 becomes—23 moss/m H.H Hm.m magma Teams mmmsm> woozmonchHm no «on HmoHHmHHSm H E .H. .mmofim madman c983- cmnoum mam comp: .Smowm .3 H030 Ho maofiwzmtwo haomomm so“ momfimcw Hmofimflfim was mcofiwgom mumcnfim .mowmuo>m «a a o .m H. .o H a .H m .o a N .H. swarmiémgmose H.H.HSH ”dams wail” Eo¢xm+mGH .m Teams 9on2; mafia mg .m Teams Hafiz: foams mHomo+.\.oH. .H. Teams. m.oHH..H mail. $qu .m mmocmochmHm no men HSHHmHHmHm H EH .H. .mooflm madcap voHonuaoNowm mew. Gmuoum .nmonm .3 ~63 5508 Ho mcoHHmbtwo anomcom .HoH mombmcm HmoHHmHHSm new 9833\me numcsfim demeaning.-- . N. 3nt 42 .CbmH .HHonSQV ”28.8.33 hflnmowflamflm Ho: 9:... on: 29$ 9% ,3 vmpoomnovcs mogm>m Haifa Tonga Nessa mmmHoZHHamEHmBH mesa...” foams mega 23.5fm? .m Teams foafim maul; ...HGH .m foams Yoga for; mHomo+sos .H. mafia Teams Tonga .58. .m mc Ho mcoHHmHHHm>o mpomcom .HoH momfimcm Hwoflmflfim cam 9833206 vumcnfim .mommuofiw: .w 3an 43 banana flavor although panelists may have been influenced by the appearance of the slices in their judgments of flavor. According to Jansen (1969) appearance contributes to flavor of fruit. No significant differences were noted in flavor evaluations between variables. According to Power _£__l. (1961), CaCl2 imparts a bitter or salty taste to the product when used above a certain level. The panelists indicated they detected a bitter or foreign flavor in the banana slices in syrups containing CaCl2 and the off-flavors were more evident in sli- ces in 20% syrup than in slices in 40% syrup, perhaps because the incre- ased sweetness of the 40% syrup masked off-flavors more than the 20% syrup did. Apparently excessive levels of CaClz were used in this study or per— haps the off-flavors resulting from its use were more apparent with ban- anas than with other fruits. 44 The data present no definite pattern regarding the effect of syrup concentration on the flavor of banana slices. Panelists indicated banana slices in 40% syrup (Variables 3) and IQF slices in syrup containing an increased amount of ACM (Variable 6) were too sweet. IQF slices in syrup containing the regular amount of ACM (Variable 5) were considered too sweet by the panelists in the fresh state; however, after the freezing process, panelists said a foreign flavor was present. The diverse opin- ions of the panelists are evident in the large standard deviations as shown in Table 8. 45 Clarity of syrup Panelists were asked to evaluate the clarity of syrup for appropriate variables as an indication of the tissue breakdown during the preparing, freezing and/or storing processes. Averages, standard deviations and statistical analyses for clarity of syrup evaluations are presented in Table 9. Syrups of fresh slices contained significantly fewer (P450.01) par- ticles than either syrups of frozen or frozen-stored slices, both of which scored the same, again suggesting the freezing and/or thawing process per se was responsible for the plant tissue breakdown. Fresh banana slices scored an average of 4.0 indicating the syrup was very slightly cloudy with few banana particles present. Frozen and frozen-stored slices aver- aged 3.3 showing an increased number of banana particles were present. Slices in 20% syrup (Variables l, 2) contained significantly more (PAL0.01) particles than slices in 40% syrup containing Ca012 (Variable 4) and significantly more (P¢10.05) particles than slices in 40% syrup with no CaClz (Variable 3). Average scores of 3.3, 3.2, 4.0, and 3.7 were recorded for slices in 20% syrup with and without CaClz and 40% syrup with and without CaClz, respectively. These data indicate per- centage of sucrose in the syrup was more beneficial in preventing tissue breakdown than was CaClz. .fimmH .ewoasav Sweets .AHHamoHHHHHmHm Ho: mum on: 65mm 65 i3 conoompmvo: mmHHHm>m 46 m .o H H., .m To H” m .m H.H. s 9H. swab; 238$; mvN. HVVNH Nessa Tessa. foamiv NHUwutsoHV .H. «dame. madame Haama $2. .m «v03 m.o«o.m H.531” m.on.m NHUmo+osom .N Hioama Toastm HioHHim .som .H o . . , . m < mo 0 \Q S o v; 92on emsosm smash ucmwoeh m3m€m> mmocmouHcmHm co mm; HmoHHmHHmHm H EH 9 .mmofim wcmcmn noeonucoNowm mam cmsoom .Smmcw Ho 3553 .Ho HAHHHmHo .Ho mcoHHmsHm>o NCOmcom .HoH mombwcm HmoHHmHHflm new mcoHHmH>mm Usmncflm .mmwmooiw: .m 3an 47 Objective Measurements Color of banana slices was determined using a Hunter color-difference meter while texture was measured with an Allo-Kramer shear press. Mean squares for the analyses of variance of the data are shown in Table 10 while the data used for these calculations are presented in the Appendix, Table 18. Color Analyses of variance for color measurements expressed as L or light- ness, aL or redness and bL or yellowness values revealed highly signifi- cant differences among treatments. Highly significant differences were also noted between variables for bL values. The L or lightness values. Averages, standard deviations and statis- tical analyses for L values are shown in Table 11. Fresh banana slices with syrup were significantly lighter (PAL0.01) than either frozen or frozen-stored slices which did not differ significantly. Average values of 63.0, 58.4 and 57.2 were noted for fresh, frozen and frozen-stored slices, respectively. A value of 66.0 was noted for fresh banana slices with no syrup thus showing these slices appeared lighter in color than syrup treated samples. Frozen and frozen-stored banana slices appeared slightly brown indicating enzymatic browning or other color reactions had taken place during the freezing, storing and/or defrosting processes. Jansen (1969) indicated polyphenoloxidase color reactions occurred during frozen storage of bananas. The significant interaction (P410.05) between 48 .mfifinwnona .Ho 3%: 38 .83 m o5 Hm HawoflHamea ..fianmnoum mo H96“ «coo Hon H o5 Hm Hcmowflcflmfi. mm H.308 Smdm ommé wovd mmm.m mm 56%? imam .Hmm *vwvom .m :25 .H :30 .mm 3 HSoHnHHm 3% .m How .m mmmé *mm .m 0H :oflomuopg 33...on .mmm "365‘ .3 3L. .0 pm .H m o3m€m> swam: ASH “tween .3 3.2V .3 .6me .va N Hamgmonm. A A $33, a m A Eomooum monficmxw mmmHQ-HMo£m moam> .830 .3 mo. mooawmfl mousom mougvm H562 .mooflm modems moHonucoNoum cam couch .Smopm Ho quoEousmmme $on .323 .88th .624 mam moflm> H638 oodonofiflunwofioo HoHHHHHm .Ho mocmHHwS Ho momeHfiw: .oH 3nt 49 .fimmH .cmoHHHHQv Sonatas hfiamowmnmwm «on who on: 08mm 05 .3 mohoomuoocs mogm>m m. .H a «.5 m .o H H. .3 N .H H" 9% mafia; HEEHSHH «HITS H.H«mam H.H«og 20¢. Nm+m0H .o Tasman H.Hamdm 335.3 mg .m AHHHSH ”Hanan H533 mHomutsoHV .H. w m .o a m. m. .o a m .H «d a a .H $895. sauna—mm; Toafim edema foam; Eu mmoamoaficwwm so mop Hosmsfim a. an e .Smonm mo mmgm> A .mmofim madman cough: couch...“ use. money“ m no“ mombmnw Hmoflmfifim can mcofipmgov vumnnfim .mommuozw..- .NH 3nt 52 The.bT,or yellowness values. The data of yellowness values as presen- ted in Table 13 showed fresh banana slices were significantly more yellow than either frozen or frozen-stored banana slices which were not signifi- cantly different. The average values were 23.1, 21.3 and 21.4 for fresh, frozen and frozen-stored banana slices, respectively, and 21.6 for fresh slices with no syrup. These data for frozen and frozen-stored slices support the L and aL values showing that color reactions and/or enzymatic browning took place during freezing and storing. Color reactions may have also occurred on the surfaces of banana slices with no syrup during the color measurement process. It is also possible that color reactions due to enzymatic browning occurred during defrosting and serving as the banana slices warmed and were exposed to air. Banana slices frozen in syrup (Variables 1, 2, 3, 4) were signifi- cantly more yellow (P410.01) than IQF slices (Variables 5, 6) thereby suggesting the presence of syrup reduced color changes during freezing and subsequent storage and thawing, probably by exclusion of oxygen. In support, Joslyn gt 31. (1948) indicated sugar syrups excluded direct con- tact of fruit tissues with oxygen. Syrup concentration had no effect on color changes since no signifi- cant differences attributable to this factor were shown (Variables 1, 2, 3, 4). In addition, the percentage of ACM did not significantly influence the extent of discoloration (Variables 5, 6). Average values of 22.4, 22.2, 23.4, 23.2, 19.9 and 20.7 were determined for slices in 20% syrup with and without CaC12, slices in 40% syrup with and without CaClZ and IQF slices in syrup with regular and increased amounts of ACM, reSpec- tively. 53 .fimmfi .cwoasnv goofing hfiuzwoflfifimfim you one on: mfimm ofi .3 wouoomuovas $5“um mane: e; um: was”? mmmpmgéogmfie foam? 935.2 Toamam 20 unosofim moocmoflficmwm “Gogmouh. Roamssm .mooflm madcap cough- couch.“ cam nououm .zmob mo mason“ -oLSmmoS among smog"... p8. mombmcm fimofimfiflm new $833.56 cumvcflm .mommumiwa- .wH 3an 56 data do not show the same rank orderings for the variables as was evident in sensory evaluations of visual texture and mouth feel. Variable aver- ages of 0.30, 0.28, 0.34, 0.29, 0.47 and 0.39 were recorded for slices in 20% syrup with and without CaClz, slices in 40% syrup with and without CaClz and IQF slices with regular and increased amounts of ACM, respec- tively. Because there were no significant differences between banana slices in syrups with added CaClz (Variables 2, 4) and those in syrups with no added CaClz (Variables l, 3) the data showed that CaClZ had no firming effects on the banana slices. These data are in disagreement with that of Loconti gt 31. (1941); however, the tomatoes used in their study were heat processed and hence, different results might be expected. 57 Moisture Content Values for the moisture content of fresh, frozen and frozen-stored banana slices appear in the Appendix, Table 20. Treatment averages for the moisture content of fresh, frozen and frozen-stored banana slices contained significantly more (P<10.0l) moisture than either frozen or frozen-stored banana slices which did not differ significantly . Banana slices frozen in 40% syrup (Variable 3, 4) contained significantly less (P40.01) moisture than slices frozen in 207. syrup (Variable 1, 2) or IQF banana slices (Variable 5, 6) as shown in Table 15. 58 .Cbmfi 6.8555 30.823 .ndhmoflfizmwm “on mum on: 393 65 .3 60.809393 mogm>w E .m a 8.2. mm .m H mm .2. em a a 3 .2 «$33.. samfimmce 3425.3 $543.2. 3543.3 29.. 03.3.3: .m $445.5 $548.2. 5.3.8.3 mm: .m fimadvva 8; «$8 2; «8.; $343.: «Emotes. .4 «VMIUI 3.04%? $543.5 2.442.? sow .m 3443.? 3448.2 3; 45.2. Nanci?” .N 5545.2. 24 «313 $4 42.? son .H o\o 8.0 v m o concur. “Bumbag Smwnh mfinmfiumxw ..GoNOLh woonmoaficwwm acogmoufi Rosmssm .moofim «canon concamucmuoh cam Genoa.“ .Smoum .8 33:00 925305 no.“ mombmcm Hmofimfifim bum mcofimgov Uhmvzflm .momafiozw: .3 3nt 59 Ascorbic Acid Ascorbic acid retention in the banana slices was measured at each period for every variable as an indication of product quality using the modified osazone method (Schwartz E£.El" 1955) to determine the total ascorbic acid content. Treatment and variable values for each replication appear in the Appendix, Table 19 while mean squares calculated from the data are shown in Table 15. The analyses indicated both treatments and variables contributed to highly significant differences. Data as shown in Table 16 indicate frozen-stored and frozen banana slices were significantly higher (P430.01) in total ascorbic acid con- tent than fresh banana slices. This fact is in conflict with the gen- erally accepted procedure of using the disappearance of ascorbic acid as an indication of deterioration in foods. Payne _£_gl. (1967) studied the ascorbic acid retention in corn quick frozen on the cob and reported that the ascorbic acid content was significantly increased immediately after freezing. Furthermore, the ascorbic acid content increased after frozen storage. Schreiber e£_al. (1958) reported that the increase in the ascorbic acid content of potatoes coincided with a decrease in redu- cing sugars. Loewus E£.§l- (1958) and Isherwood _£‘_l. (1954) stated that ascorbic acid was an intermediate product in carbohydrate metabolism and hence, the generation of the vitamin in frozen—stored products was possible. The results of this study may support these conclusions; but, banana slices may have absorbed ascorbic acid from the syrups during free- zing, storing and/or thawing thereby increasing the total content. Also, the moisture content of the frozen and frozen-stored banana slices was 60 Table 16. --Ana1ysis of variance for determining the effect of treatments and variables on the ascorbic acid content of banana slices. Source of Variance Degrees of Freedom Mean Squares Treatment 2 65. 815** Variable 5 17. 518** Interaction 10 7. 774 Subtotal 17 17. 468** Within 36 2 . 43 8** Total 53 **Significant at 1 per cent level of probability. 61 less than the fresh slices, thus contributing slightly to the apparent increase in ascorbic acid in the frozen and frozen-stored slices. Fresh banana slices had an average ascorbic acid content of 12.3 mg/100 g of fruit while frozen and frozen-stored slices contained an average of 15.4 and 15.7 mg/100 g of fruit, respectively. IQF slices with the regular amount of ACM in the syrup (Variable 5) had significantly lower (P410.01) ascorbic acid content than banana slices in syrup or IQF slices with an increased amount of ACM in the syrup (Vari- ables 1, 2, 3, 4, 6). In addition, bananas with 40% syrup containing CaC12 (Variable 4) had less (P410.05) ascorbic acid than IQF slices in syrup with an increased amount of ACM. Variable averages were 15.2, 14.6, 14.2, 14.6, 12.0 and 16.2 mg/100 g of fruit for slices in 20% syrup with and without CaClz, slices in 40% syrup with and without CaClz and IQF slices with regular and an increased amount of ACM, respectively. ‘ The data indicate the ascorbic acid present on IQF slices in syrup with regular amounts of ACM was utilized to prevent color reactions during freezing, storing and/or thawing; hence, reduced levels were present in this variable. Fresh banana slices without syrup were analyzed for total ascorbic acid. The data showed an ascorbic acid content of 6.7 mg per 100 g of banana slices. This value was in the range of those reported by Harris g£.§l. (1939) as shown in Table 2. 4 The syrups used to pack banana slices were also subjected to analysis for total ascorbic acid content using the same methods and storage periods where applicable as for banana slices. Average ascorbic acid contents based on one trial of each of the five syrups containing 1% ACMiwere 62 .Cbmfi .Gwocsmv 523.3“. Eucwouwamwm you was man mama m5 .3 concomuovg mo3m>m w .H a s .3 m; a v ...: m .m a m .2 “twang... “swung; ~10“de oéflog: o.mHo.: 20¢ Nm+mGH .m mvv w.on.NH m.HHm.mH o.mHo.oH “23 .m m.m.~.m.va mdfimdfi H.mH~..mH mAHde NHUmU+$ow .w o.m«m.S Tail: 2;“de so... .m Wflv< m.on.mH méfimdfi w.oHN..mH mHUmU+§om .m vdfimdfi mAHmbH o.mHm.NH skew .H moo1m§ mod Vnm Hodvm U m < ..WMMWWE cowoum nmoph ozflum > mmozwoflfizmwm «cmgwonfi Ecumsfim mo 33:00 Bow oEnoamm no.“ .mmofim madame. c933: conch.“ cam Genoa.“ Emma.“ £93me awoflmflflm can. aofiwgov vnmncfim £69303»... .5 3nt 63 27.2 i_3.9, 28.7 i 2.7 and 27.8 i 5.0 for syrups used for fresh, frozen and frozen-stored banana slices, respectively. The standard deviations show considerable variance among the syrups used for each treatment of banana slices. When 3% ACM was added to the syrup, values of 28.3, 34.3 and 35.0 were determined for syrups used for fresh, frozen and fro- zen—stored banana slices. SUMMARY AND CONCLUSIONS The primary purpose of this investigation was to determine the effect of freezing methods in combination with syrup concentration on the quality characteristics of banana slices. A second purpose was to investigate the effect of CaCl2 on the textural qualities of frozen banana slices and the effect of ACM in maintaining color of IQF banana slices. All of the bananas used in this investigation were Chiquita brand obtained from a local wholesaler. All data reported were the average of three repli- cations. Quality characteristics of the banana slices were evaluated by a six-member taste panel. The results indicated that the visual texture of fresh banana slices was scored significantly higher (P‘L0.01) than either frozen or frozen-stored slices and the banana slices in 40% syrup scored higher (P4 0.01) than slices in 20% syrup. The addition of CaC12 did not significantly affect the score of visual texture. The color of fresh banana slices in syrup was scored significantly higher (P410.01) than either frozen or frozen-stored slices and the slices in syrups were significantly lighter (P‘10.01) than IQF slices. The addition of an increased amount of ACM in syrups used for IQF slices did not affect the score of color. Fresh banana slices in syrup scored significantly higher (P410.0l) in mouth feel than frozen-stored slices which in turn scored higher 64 65 (P410.0l) than frozen slices. No significant differences were noted be- tween variables. The improved mouth feel during frozen storage probably reflected the variance in the evaluation by the panelists. The flavor of fresh banana slices was scored significantly higher (PAL0.0l) than either frozen or frozen-stored slices, both of which were not significantly different. In addition, no significant differences were noted between variables. The data for clarity of syrup showed syrups of fresh slices con- tained significantly fewer (PAL0.01) particles than either frozen or frozen-stored slices, both of which scored the same. Slices in 20% syrup contained significantly more (P410.0l) particles than slices in 407. syrup with Ca012 and significantly more (PL0.05) particles than slices in 40% syrup with no CaClZ. These data, as with scores of visual texture, suggested that percentage of sucrose in the syrup was more effec- tive in preventing tissue breakdown than was CaClz. Thus, the fresh banana slices in syrup scored significantly higher (P410.0l) in all of the quality characteristics evaluated by the taste panel than either frozen or frozen-stored banana slices. These data suggested that the freezing and/or thawing process pg; s3 damaged the cellular structure of the banana slices and was detrimental to the qual- ity characteristics of the banana slices. The Hunter color-difference meter was used to determine the color of the banana slices. Analyses of the data indicated that fresh banana slices in syrup were significantly lighter and more yellow (P410.0l) in color than either frozen or frozen-stored banana slices, both of which were not significantly different. The frozen-stored banana slices had 66 significantly higher (P4fi0.0l) redness values than either fresh or frozen banana slices. As with the sensory scores for color, slices in syrups were significantly more yellow (P<{0.0l) than IQF slices. There were no significant differences in lightness and redness values between variables. The addition of an increased amount of ACM in syrups used for IQF slices did not significantly improve the color measurements of IQF slices. Sig- nificantly high positive correlation coefficients were found between lightness and yellowness values and sensory scores for color. The high negative correlation coefficient between redness values and sensory scores for color showed an inverse relationship between these two measure- ments. The Allo-Kramer shear press was used to determine the texture of the banana slices. Analyses of the data revealed that fresh banana slices were significantly firmer in texture (P410.01) than either frozen or frozen-stored slices which did not differ significantly. The IQF slices were significantly firmer in texture (P40.0l) than slices packed in syrups. The high correlation coefficients between shear press measure- ments and visual texture and mouth feel indicated that the instrument and the taste panel evaluated the same quality characteristic of the banana slices. Ascorbic acid retention in the banana slices was measured by the mod- ified osazone method to determine the total ascorbic acid content. The data indicated that frozen and frozen-stored banana slices were signifi- cantly higher (P410.0l) in ascorbic acid than fresh banana slices in syrup, probably due to the generation of the vitamin during frozen stor- age and/or absorption of ascorbic acid from the syrup. Loss of moisture 67 from frozen and frozen-stored banana slices contributed slightly to an apparent increase in ascorbic acid calculated on a wet weight basis. The IQF slices with the regular amount of ACM in the syrup contained less (PAL0.01) ascorbic acid than the other variables, indicating that the ascorbic acid in this variable was utilized to prevent color reactions during freezing, storing and/or thawing. Thus, fresh banana slices were superior in all subjectively evaluated or objectively measured quality characteristics. The data indicate it was the freezing and/or thawing process pg£_§g which was detrimental to the quality characteristics of banana slices because few significant differ- ences were found between the characteristics of frozen and frozen-stored banana slices. The data present no clear-cut pattern regarding the effec- tiveness of syrup concentration in maintaining quality during freezing and storing; however, trends of the data suggest 40% sucrose syrup is superior to 20% sucrose syrup in preserving texture in banana slices. The limited data of this study indicate the use of CaCl was not beneficial in pre- 2 serving quality characteristics and because of the bitter flavor imparted to the banana slices, its use would not be recommended. For IQF banana slices, the use of ACM at a 3% level was more beneficial than use at a 1% level in maintaining quality. No definite pattern existed in the data regarding the merits of syrup-packed or IQF banana slices. The use of ACM increased the ascorbic acid content of banana slices and further increases in the ascorbic acid content were noted after freezing and after storage, probably due to the absorption by the banana slices. The findings of this study suggest other methods, such as freeze drying, should be investigated for processing bananas. Also, other 68 treatments, such as sulfur dioxide, to deter or prevent color reactions during processing and storing should be investigated. Microscopic study of banana tissues and changes incurred during freezing is basic to fur- ther investigations of this processing method. Studies of the enzymes present in bananas as well as changes occurring during processing would provide basic information pertinent to further investigations. LITERATURE CITED AOAC. 1960. "Official Methods of Analysis." 9th ed. Assoc. Offic. Agr. Chemists. Washington, D.C. page 264. Aylward, F. and D.R. Haisman. 1969. Oxidation systems in fruits and vege- tables - their relation to the quality of preserved products. Adv. Food Research 17:1. Balls, A.K. and W.S. Hale. 1935. Peroxidase in the darkening of apples. Ind. Eng. Chem. 27:335. Barnell, H.R. and E. Barnell. 1945. Studies in tropical fruit - The dis- tribution of tannins within the banana and the changes in their condition and amount during ripening. Ann. Botany 9:77. Bogert, L.J. 1942. Dietary uses of banana in health and disease. United Fruit Co., Research Dept., New York. Boggs, M.M., W.C. Dietrich, M.D. Nutting, R.L. Olson, F.Z. Lindquist, G.S. Bohart, H.J. Neumann, and H.J. Morris. 1960. Time-temperature tolerance of frozen foods, XXI. Frozen peas. Food Technol. 14:181. Borgstrom, G. 1961. Unsolved problems in frozen food microbiology. In "Proceedings of Low Temperature Microbiology Symposium." Campbell Soup Co. Camden, N.J. ' Braverman, J.B.S. 1963. ”Introduction to the Biochemistry of Foods." Elsevier Publishing Company, New York. Brekke, J.Z. and L. Allen. 1967. Dehydrated bananas. Food Technol. 21:1391. Cain, R.F. 1967. Water-soluble vitamins - Changes during processing and storage of fruit and vegetables. Food Technol. 21:998. Davis, L.G. 1956. Below zero temperature important for vitamin reten- tion in frozen foods. Food in Canada 16(4):24. Dietrich, W.C., F.E. Linquist, and M.M. Boggs. 1957. Effect of maturity and storage temperature on quality of frozen peas. Food Technol. 11:485. 69 70 Dietrich, W.C., M.M. Boggs, M.D. Nutting, and N.Z. Weinstein. 1960. Time- temperature tolerance of frozen foods. XXIII. Quality changes in frozen spinach. Food Technol. 14:522. DuBois, C.W. 1949. Ascorbic acid and color in food products. Food Technol. 3:119. Duncan, D. 1957. Multiple range test for correlations and heteroscedas- tic means. Biometrics 13:164. Esselen, W.B., Jr., C.R. Fillers, and J.E. McConnell. 1949. Frozen apples and apple products. Food Technol. 3:121. Fennema, O. and W.D. Powrie. 1964. Fundamentals of low-temperature food preservation. Adv. Food Research 13:219. Griffiths, L.A. 1959. Detection and identification of the polyphenol oxidase substrate .f the banana. Nature, London, 184:58. Griswold, RJM. 1962. "The Experimental Study of Foods." Houghton Mifflin Company, Boston. Guadagni, D.C., C.C. Nimmo, and E.F. Jansen. 1957. The time-temperature tolerance of frozen foods. II. Retail packages of frozen peaches. Food Technol. 11:33. Guadagni, D.C. 1969. Quality and stability in frozen fruits and juices. In Van Arsdel, W.B., J.J. Copley, and R.L. Olson. "Quality and Stability of Frozen Foods." Wiley-Interscience, New York. Harding, 1. 1951. "How to Freeze Foods." International Harvester Com- pany. Harris, P.L. and G.L. Poland. 1937. Organic acids of the ripe banana. Food Res. 2:135. Harris, P.L. and G.L. Poland. 1939. Variations in ascorbic acid content of bananas. Food Res. 4:317. Heiss, R. 1942. Verfahrenstechnische Untersuchungen hber die Guteverbes- serung von Gemfise-und Obstdauerwaren. Zeitschrift fur die ges. Kalte-Industrie 49:131, 142. Hodgman, C.D., R.C. Weast, and S.M. Selby. 1959. "Handbook of Chemistry and Physics." 4lst ed. Chemical Rubber Publishing Co. 2310 Superior Ave., N.E., Cleveland, Ohio. Isherwood, F.A., Y.T. Chen, and L.W. Mapson. 1954. Synthesis of L- ascorbic acid in plants and animals. Biochem. J. 56:1. 71 Jansen, E.F. 1969. Quality-related chemical and physical changes in frozen foods. In Van Arsdel, W.B., M.J. Copley, and R.L. Olson. "Quality and Stability of Frozen Foods." Wiley-Interscience, New York. Joslyn, M.A. and L.A. Hohl. 1948. The commercial freezing of fruit products. Calif. Agr. Expt. Sta. Bull. 703:1. Joslyn, M.A. 1949. Use of liquid sugars in freezing of apricots, peaches and nectarines. Food Technol. 3:8. Joslyn, M.A. and J.D. Ponting. 1951. Enzyme-catalyzed oxidative brown- ing of fruit products. Adv. Food Research 3:1. Joslyn, M.A. and H.C. Diehl. 1952. Physiological aSpects of low temp- erature preservation of plant products. Ann. Rev. Plant Physiol. 3:149. Kertesz, Z.I., T.G. Tolman, J.D. Loconti, and E.H. Ruyle. 1940. The use of calcium in the commercial canning of whole tomatoes. New York Agr. Expt. Sta. at Geneva, New York. Technical Bull. 252:3. Lawler, F.K. 1967. Banana challenges food formulators. Pt. I. Food Eng. 39(5):58. Lee, I.A., W.A. Gortner, and J. Whitcombe. 1949. Effect of freezing rate on fruit. Food Technol. 3:164. Levitt, J. 1960. Freezing injury of plant tissue. Ann. New York Acad. Sci. 85:570. Loconti, J.D. and Z.I. Kertesz. 1941. Identification of calcium pectate as the tissue firming compound formed by treatment of tomatoes with calcium chloride. Food Res. 6:499. Loewns, F.A., B.J. Finkle, and R. Jang. 1958. L-ascorbic acid: a poss- ible intermediate in carbohydrate metabolism in plants. Biochim. Biophys. Acta 30:629. Lynch, L.J., A.T. Chang, J.C.N. Lum, G.D. Sherman, and F.Z. Seale. 1959. Hawaii food processors handbook of fruits, vegetables, meats and fish. Hawaii Agr. Expt. Sta. Circular 55. MacArthur, M. 1948. The effect of method of freezing, type of the pack and storage on aSparagus tissue. Sci. Agr. 28:166. Meyer, L.H. 1960. "Food Chemistry." Reinhold Book Cooperation, New York. Meyer, H. 1964. "The Complete Book of Home Freezing." J.B. Lippincott Co., New York. 72 Miller, C.D. and K. Bazore. 1945. Fruits of Hawaii. Hawaii Agr. Expt. Sta. Bull. 96. Onslow, M.W. 1920. Oxidizing Enzymes. III. The oxidizing enzymes of some common fruit. Biochem. J. 14:541. Palmer, J.K. 1963. Banana polyphenoloxidase. Preparation and proper- ties. Plant Physiol. 38:508. Payne, I.R. 1967. Ascorbic acid retention in frozen corn. J. of The American Dietetic Association 51:344. Ponting, J.D. and M.A. Joslyn. 1948. Ascorbic acid oxidation and brown- ing in apple tissue extracts. Arch. Biochem. 19:47. Powers, J.J., D.C. Downing, and I.T. Powers. 1961. Effect of acid level, calcium salts, monosodium glutamate, and sugar on canned pimientos. Food Technol. 15:67. Reeve, R.M. 1970. Relationships of histological structure to texture of fresh and processed fruits and vegetables. J. of Texture Studies 1:248. Rogers, J.L. 1958. "Quick Frozen Foods." Food Trade Press, Ltd., London. Rudra, M.N. 1936. Distribution of vitamin C in different parts of common Indian foodstuffs. Biochem. J. 30:701. Schreiber, J.S. and M.E. Highlands. 1958. A study of the biochemistry of irradiated potatoes stored under commercial conditions. Food Res. 23:464. Schwartz, M.A. and N.J. Williams., Jr. 1955. New procedure for ascorbic acid analysis by osazone. Proc. Soc. Expt. Biol. and Med. 88:136. Siegel, M. 1939. The effect of calcium salts in canning tomatoes. The Canner 90(2):12. Simmonds, N.W. 1966. "Bananas." 2nd ed. Longsmans, Green and Co., Ltd., London. Simon, M., J.R. Wagner, V. Ct. Silveira, and 0.2. Hendel. 1955. Calcium chloride as a non-enzymic browning retardant for dehydrated white potatoes. Food Technol. 9:271. Thornton, N.C. 1963. Carbon dioxide storage. XIV. The influence of carbon dioxide, oxygen and ethylene on the vitamin C content of ripening bananas. Contrib. Boyce Thompson Inst. 13:201. Tressler, D.R. 1943. "The Freezing Preservation of Foods." The AVI Publishing Company, Inc., Westport, Connecticut. - 73 Udenfriend, S., W. Lovenberg, and A. Sjoerdsma. 1959. Physiologically active amines in common fruits and vegetables. Arch. Biochem. Biophys. 85:487. Von Loesecke, H.W. 1969. "Bananas." Interscience Publishers, Inc., New York. Wenkam, N.S. and C.D. Miller. 1965. Composition of Hawaii Fruit. Hawaii Agr. Expt. Sta. Bull. 135. APPENDIX 75 Figure 1. INSTRUCTIONS TO TASTE PANEL MEMBERS FOR EVALUATING FROZEN SLICED BANANAS General Instructions 1. Do not smoke, chew gum, or partake of food or beverage during the 30 minutes before the taste panel session. Sit at the same place in the room for each session. Code numbers for each sample will be attached to each dish. Check to be sure the code on the score sheet matches that on the dish. Your name should be written on each score card. Since facial or vocal expressions may influence the scoring of other taste panel members, please avoid these during each session. Samples of sliced bananas will be served to you to evaluate one at a time. Evaluating Bananas 1. To understand the terminology used in the score card, please study the following drawing. fleck placenta As you evaluate each characteristic, check the space which best fits your judgment for that characteristic. Evaluate the visual texture characteristic first without disturbing the sample and then evaluate the rest of the characteristics. Check to be sure you have evaluated each characteristic for each dish of bananas. You may leave the room after evaluating six samples of bananas. 76 000.50 8 00000.0 00030 000000 000 0000 «0000 0000m- .N 000000 "whim—2200 00003000 000000 00000 mbmhm 000000 00000002: 00—03000 000000 00 000800 00000008 00 0303000 30.0 50! 8 0000000 000000 .00 - 000 033 000000 h00> >008 503 A0006 0:3 00:30 mflamfim 03030 030300 80> .00 00003000 300 000 > #853300 .00>0G 03000.0 00 .00>0d .00>0G 0000000 .0020: 0000000000 30800330 000800000 000 > -000 30000002 0000000000 .2295 0000000000 000. - 00 “00050000 000020 .0033 000000 033000 .00>0G 000000 .0020: 80> 0:3 «00.30 .0900. 000000 02 -000 500020 000 > 033000000 0503mm 000000 033000000 300000030 000 30:05 £00,300 .0030 .0020 000000 «00000005 .0020 000000 000000 80000005 .0020 .08 80. 08 0082082 39.0025 000 30008 00.0000 0. 5%.. 3200.505 8038b .30000 .0000308 40000008 005 00800 500003 40000008 000500 00820000000 :00 AS0308 000500 0005000005 00000000 .5008 .00 00000000 - 0008 :00 5080.500 80> 503 0030050 10.35 0000300 503 050030 5:. 00300.50 3 0.00000 0300» 503 0030000 000500 000500 800000 0030050 000500 008500 800000 «3 05000000 0000000 0000 0000000 00 0003 000. 00 0003 300000002 0.000000 00 00000. 00 0003 303$ 0003 00000 0880.: 5002 0803000 000.800 02 00.000 .50000—0 08000—0 8 000030 00500 5; 500030 00003000 00 008.3000 000.0000 8 «00080 0008 0008 8 0033 05 «000300000 3050.» 000300000 02080000m «0 «00080 0000000: $80.30: 0000000 Lien 008000 «03m. 50! 000:0.» 080000 mO-HOU 6352005 .0800 0322:0500. -305 0800 .0380 50s 05 05.0080. 0:20:20 05003: 85> 008000 300000800 00 000080 0300008 .00 000080 00000002 .00 «00080 00005 00020 «00- 0006 magnum. n N n v m 0000a 0003. £80 300 mm 016 0C .0023 0000000 .00>0G 0000000000 308056 0000000000 80> -000 53000002 0000000000 5903.8 00080050 «03 , 00 00003500 050030 .00>0u 035000 .0020: 80> 50B «0030 .00>0¢ oz -000 0500.20 80> 035000000 05038 .00>0fl 035000000 000000000 000 30502 ”000530 .0020 00 5000 .0000 «00.30005 300.005 038000000: 0003 2080 h00> .0000 .303 030300 6083000 800005 000000 ...—00000005 300 000. 503 «.000 #3000005 503 008000 00 tom 000.0000 503% 005 03.000 300003 .5008 00 00000000 3 300000 0300» 033000000: 500000005 0003 00 500000005 500000005 zu03 50b 3.0000000 030000 ~00.“— 0u03 00 0000000 000. 800000 53000005 0903 00 0000000 00 800000 05035 0003 00000 083000 3002 00052.. 0000000 02 03030 080030 080030 8 000030 03000 503 300030 00000000 00 058500 008000 8 000030 0008 0008 00 0033 03 «00030005 30:00 000300000 D0805um 00 500080 300000: 0503000 00305 -0I000 008000 «03% 05B 50:0.» 080000 £0400 633000000 .0800 03230000000 - 00.5 .800 .0380 £03 :5 000.302. .0000: ..o 000808 .0000: .8 050008 0a 050; 00830 33000800 00 «00080 3000002 00 000080 0058 «00080 «050 .90 > 00030 «00- 0030 HGPHKHP H N n v m 0008 0003. ~30 78 Table 18. --Averages for five panelists of three replications of sensory evaluations of the quality characteristics of fresh, frozen and frozen-stored banana slices. $33.} $3 Treatment g ‘3 g E Fresh Frozen Frozen -stored 5" > 1 2 3 1 2 3 1 2 3 Visual‘ 1 3.6 4.3 4.0 2.3 1.8 2.8 2.8 2.8 2.5 Tenure 2 3.0 4.0 4.2 2.5 2.8 3.0 2.0 2.2 2.7 3 4.4 4.8 4.2 3.2 3.0 2.8 3.2 3.0 3.0 4 4.4 5.0 4.3 4.0 3.4 3.2 4.0 3.2 3.7 5 3.4 4.5 4.3 3.5 3.0 3.0 3.7 3.3 3.3 6 4.8 4.8 4.7 4.0 4.0 3.8 3.3 3.2 3.0 Color 1 4.6 4.8 4.7 4.0 3.2 4.5 3.8 2.7 2.8 2 4.4 4.5 4.8 2.7 4.0 3.3 4.2 3.7 3.0 3 4.6 4.5 4.5 3.7 4.0 4.0 4.3 4.2 3.5 4 4.4 4.5 3.8 4.2 4.0 3.6 3.8 2.3 4.7 5 3.8 4.8 4.7 2.3 1.6 2.0 1.5 1.2 1.0 6 5.0 5.0 4.7 2.3 2.2 2.5 1.8 2.3 2.3 Mouth 1 4.2 4.0 4.0 1.7 2.0 2.3 2.2 2.5 2.7 Feel 2 4.4 4.0 4.5 1.3 2.3 2.3 2.7 2.2 2.2 3 4.2 4.5 4.5 1.5 1.6 1.0 2.8 2.7 2.0 4 4.4 5.0 4.0 2.5 1.6 1.2 3.2 2.5 3.0 5 3.8 4.3 4.3 2.2 1.8 1.0 2.8 2.2 2.5 6 4.2 2.8 4.2 2.2 2.7 2.7 2.7 2.5 2.5 Flavor 1 4.0 4.5 2.4 2.7 3.3 3.3 2.7 3.0 2.3 2 4.0 3.3 3.5 2.7 2.5 2.5 2.7 2.3 2.7 3 4.0 3.5 4.3 3.2 2.4 3.0 2.7 2.8 2.5 4 4.4 4.0 3.5 2.3 2.0 2.8 3.3 2.2 3.0 5 3.8 3.8 3.3 2.2 2.6 3.4 2.8 2.5 3.2 6 4.4 2.8 3.7 2.8 2.7 2.8 2.8 3.0 3.3 Clarity 1 3.0 3.8 3.3 2.8 2.5 3.3 3.0 3.0 3.7 Sy‘filp 2 3.0 4.0 3.5 3.0 3.7 3.5 3.2 3.0 2.7 3 4.4 4.5 4.5 2.8 4.0 3.2 3.5 3.2 3.0 4 4.2 5.0 4.2 4.0 3.6 3.5 3.7 3.5 3.8 79 Table 19. «Values for three replications of Hunter color difference and A110 -Kramer shear press measurements of color and texture, respectively, of fresh, frozen and frozen- stored banana slices. 3 Treatment Measure- g Fresh Frozen Frozen-stored ment 3 >’ 1 2 3 1 2 3 1 2 3 L.Vaiuea 1 64.3 61.4 62.3 60.9 56.3 56.3 55.5 56.7 57.9 2 63.4 62.8 63.2 56.9 58.3 58.1 55.7 57.5 57.2 3 62.6 60.4 61.7 56.2 60.6 57.7 60.1 58.1 59.4 4 60.0 60.8 63.9 57.9 60.3 59.7 60.2 56.6 56.8 5 63.1 64.9 64.1 58.8 60.5 57.2 56.5 52.2 56.1 6 65.5 65.0 63.3 56.4 59.3 59.3 57.4 57.0 57.1 aL Values 1 -0.2 1.5 1.5 -0.5 2.0 2.3 2.8 2.0 2.9 2 0.4 1.6 1.2 0.4 0.4 1.3 1.3 2.2 3.0 3 0.4 1.4 1.5 2.2 1.7 1.6 2.0 2.1 3.1 4 1.7 1.6 1.1 1.2 1.9 0.6 3.0 2.5 2.2 5 1.1 0.4 1.1 1.9 1.5 1.4 3.4 2.0 2.7 6 1.4 1.4 1.2 2.0 2.6 2.0 3.0 3.1 3.2 51 Values 1 20.1 23.1 23.9 18.8 20.9 23.7 23.4 22.5 22.7 2 22.9 23.7 24.3 21.5 22.5 21.4 19.2 23.1 23.4 3 22.5 24.9 23.1 22.8 22.3 24.0 22.3 23.2 23.8 4 22.6 24.3 23.6 23.0 22.8 24.1 23.9 23.7 22.8 5 24.0 22.3 22.6 19.2 18.3 19.4 18.1 17.1 17.6 6 22.5 22.2 23.0 18.9 20.3 20.1 19.9 20.1 18.8 Shear 1 0.40 0.37 0.34 0.27 0.29 0.26 0.21 0.21 0120 (lb 22:17“) 2 0.39 0.40 0.42 0.24 0.26 0.26 0.26 0.25 0.23 3 0.48 0.38 0.41 0.27 0.24 0.24 0.21 0.22 0.21 4 0.39 0.65 0.45 0.25 0.26 0.31 0.25 0.27 0.26 5 0.46 0.71 0.40 0.43 0.51 0.36 0.45 0.39 0.53 6 0.44 0.54 0.42 0.31 0.35 0.31 0.36 0.36 0.40 80 vNNN. 34.2. made H.H.NH. 32:. 3.3. no.3. owdm wmdp m 3.: ova 3.3. mN.HH. moHH. mNdH. mNHl. 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