JJ- ' mammchga SUGAR flmz’aacme m $WEE ,EERESH wwmm mam“? T529323 €02» ‘E‘Ec 9.79:3?“ 3‘? M. S. fiiECHEGAN STRTE BKNEVEESEW Thomas Richard Mulvaney 1958 TH ESIB PRODUCT-INDUCED SUGAR STRATIFICATION IN SWEET, FRESH CUCUMBER PICKLES By Thomas Richard Mulvaney AN ABSTRACT Submitted to the College of Agriculture Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Food TechnOIOgy Program Agricultural Engineering Department 1958 W" Approved 5 O 1 It has been found that when a fresh food product high in water such as cucumbers, cherries, or peaches is placed in or covered with a heavy syrup changes will take place that will produce a density gradient between tOp and bottom of the Jar. The phenomenon is termed product-induced strat— ification. This thesis reports the dynamics of product-induced stratification in sweet, fresh cucumber spears from the time syrup is added to the spears, until final equalization. The results indicate that water diffuses from the cucum- ber (cherries or peaches) into the syrup and rather than mixing appreciably with the syrup rises at once to the liquid surface. This process begins immediately after adding the syrup and reaches a maximum at about 1 day with a difference between top and bottom of 20 percent soluble solids. A difference between top and bottom of 8 percent soluble solids remains after 32 days of equilibration. The magnitude of stratification was about the same for unheated and heat pro- cessed cucumber spear packs; however, the values at tap and bottom were lower for the heat processed packs. A pronounced difference in shrinkage and taste was observed between the top and bottom of the cucumber spears from 1 to 32 days after canning. Thomas Richard Mulvaney PRODUCT-INDUCED SUGAR STRATIFICATION IN SWEET, FRESH CUCUMBER SPEARS By Thomas Richard Mulvaney A THESIS Submitted to the College of Agriculture, Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Food Technology Program Agricultural Engineering Department 1958 /’/(J ' ‘3“? C»- 7 “if? 51 6:0 ,n/Lw‘ ”‘- ACKNOWLEDGMENTS The author wishes to eXpress his sincere appreciation to all who have contributed to-this investigation. The contributions of the following are especially recognized: Dr. I. J. Pflug, Agricultural Engineering Department, as major professor continually provided counsel, guidance, and support throughout the entire investigation and the writing of this thesis. Dr. B. C. Nicholas, Agricultural Engineering Department, contributed many hours of guidance in eXperimentation and made many helpful suggestions in the writing of this thesis. Dr. J. L. Fairley, Chemistry Department, Dr. w. D. Powrie, Agricultural Engineering Department, and Dr. G. M. Trout, Dairy Department are sincerely thanked for their interest and helpful suggestions. Dr. A. w. Farrell, Head, Agricultural Engineering Depart- ment, for his interest and allocation of funds for this investigation. Betsey, my wife, for her faith and support and for assistance in preparing and typing the manuscript. TABLE OF CONTENTS Page INTRODUCTION............................................ 1 REVIEW OF LITERATURE.................................... 2 EXPERIMENTAL PROCEDURE.................................. 11 RESULTS................................................. 25 Visual Studies..................................... 25 Studies on Unheated Fresh Cucumber Pickles......... 26 Studies on Heat Processed Fresh Cucumber Pickles... 31 Studies on Product-Induced Stratification in Other Products................................... nu DISCUSSION OF HESULTS................................... #6 SUMMARY AND CONCLUSIONS................................. 5? BEFERENCES.............................................. 59 INTRODUCTION Sugar is added to canned fruits and vegetables to improve flavor, texture, color and consumer acceptance. In fact, certain products must be packed in heavy syrup to be marketable. Some pickle products have sugar added, for example, ”sweet gherkins”, ”sweet mixed chips”, and ”sweet stix”. It is obvious from the literature that there have been problems associated with the thermal processing of sweet products. Recently this laboratory noted product-induced stratification of syrup on sweet, fresh cucumber pickles. This phenomenon may explain some of the unanswered problems associated with syrup packs. Increased knowledge of product-induced stratification is necessary to facilitate an adequate understanding of the phenomenon. After understanding the problem, ways to deal with or alleviate the problem could be deve10ped. This thesis describes the dynamics of product-induced stratification in sweet, fresh cucumber Spears from the time syrup is added to the spears, until final equalization. REVIEW OF LITERATURE | Product-induced stratification has recently been ob- served by Pflug and Nicholas (21) in sweet, fresh cucumber pickles. They found that the slow rate of heating of certain syrup packed pickles could not be explained by the decrease in the rate of heating of a syrup versus a brine. They dis- covered that a density gradient (density increases from top to bottom) existed in certain syrup packed products. The gradient was so large that it could not be overcome during heat pasteurization by the thermal expansion which produces the buoyant force of convection. A slow rate of heating resulted, which was about the same as that for normal con- duction heating products. That this phenomenon occurs in the field was verified by checking commercial packs of sweet, fresh cucumber pickles. Product-induced stratification is the name given the concentration gradient of soluble solids which results when fresh cucumbers of high water and low solids content are placed in a sugar syrup. It was found that after the cucum- ber is covered with syrup, the concentration of soluble sol- ids, increases from tsp to bottom, rather than being uniform throughout the container. This is perhaps a source of prob- lems associated with the thermal processing of fruits and vegetables sweetened by the addition of a heavy syrup that have troubled canners for a number of years. 3 Bigelow, Bohart, Richardson, and Ball (0) demonstrated that No. 3 cans of 50 percent sucrose syrup exhibited an fh (slepe of semi-log heating curve expressed as time in min- utes required to traverse one complete log cycle on the temp- erature ordinate) of 6.0 minutes as compared to an fh of 3.0 minutes with water. Their investigation demonstrated that a soluble substance such as sugar dissolved in water impedes the formation of convection currents slightly and thus some- what delays heat penetration. They reported that firm plums of a large variety packed in water or 50 percent sucrose syrup required 30 and 55 minutes respectively, to reach a retort temperature of 100.0°C. (212.0°F.). They suggested that the large difference between plums and syrup alone showed the influence of the plums in retarding heat penetrat- ion by reason of the cooling action due to the slow heating of the plums to the center. Magoon and Culpepper (19) reported the greatest decrease in heating rate occurred at 60 percent sucrose when comparing 10, 30, and 60 percent sucrose syrups. Their data was of such a nature that the heating rates could not readily be determined. ' . Joslyn's (1?) data demonstrated an fh of 8.0 minutes for 50 percent sucrose syrup and an fh of 3.0 minutes for water when heated in No. 2-1/2 cans. A correlation of the sucrose solution viscosity with rate of heat penetration showed a sharp decrease in the rate at about 60 percent sucrose: however, the viscosity effect was less marked than u eXpected even at 60 percent sucrose. They concluded that viscosity would not appreciably affect commercial packs at the concentrations used. Jackson (16) reported that the rather large viscosity change which occurs from 30 to 60 percent sucrose syrup has some effect on the rate of heat penetration. He stated that this effect is not sufficient to cause much change in the length of process required for a given bactericidal effect (Fo value). Pflug, Nicholas and Mulvaney (22) found fresh cucumber spears packed in 50 percent sucrose syrup had an fh of no min- utes compared to an fh of 21 minutes in brine. Plastic obyects the shape of cucumber spears had an fh of 12 minutes in 50 percent sucrose syrup and an fh of 10 minutes in water. It was found that 50 percent sucrose syrup had an fh of 13 min- utes as compared to an fh of 11 minutes for water. Sixteen- ounce Jars were used in all of these determinations with the thermocouple located on the vertical axis of the Jar 1.8 cm. from the bottom (slowest heating point). The literature presented above shows that viscosity and syrup concentration (density) do not adequately explain the decreased rate of heating (increased fh's) which usually accompanies the use of heavy syrups on products. Braun (6,7) has reported information on dry sugar in- duced stratification in sweet potatoes which suggests the effect product-induced stratification may have on heat pene- tration in sweet, fresh cucumber pickles. 5 Braun, Hays, and Benjamin (7) stated that, "dry sugar at the bottom of food cans or Jars with no subsequent agitat- ion does not completely dissolve during heat sterilization and stratification of sugar syrups are formed in the contain- er. These strata retard heat transfer to the interior of the can contents. Apparently the larger part of the decrease in the thermal efficiency of the process is accounted for by the effect of the dense viscous sirup in the lower part of the can in retarding the convection currents which normally speed the rate of heat flow into the container of canned sweet potatoes.“ Ball and Olsen (2) have reported that the rate of con- vection currents depends on the difference in densities be- tween rising and falling liquids at any level and upon the resistance to flow or the viscosity, therefore any affect that prevents this positive difference in density would pre- vent convection. Directly associated with decreases in lethality of a heat process due to retardation of-heat transfer would be the possibility of some protective effect being imparted to potential spoilage organisms due to the high concentrations of sucrose, which occur near the container bottom. Braun, Hays, and Benjamin (8) demonstrated a protective effect of high concentrations of sucrose upon food spoilage organisms (non—acid food, sweet potatoes) during heat pro- cessing, however bacterial spores extremely tolerant to osmotic influences were used in their tests. 6 Etchells and Goresline (11) and Etchells and Ohmer (12) have found that the two main groups of organisms responsible for spoilage of pasteurized fresh cucumber pickle products are acid-forming bacteria and yeasts. Robbins' (23) results indicated that these lactic acid bacteria would survive higher pasteurization levels than yeasts. He identified many and determined the resistance of some of the microorganisms causing spoilage in presumably pasteurized sweet, fresh cucumber pickles. The acid-forming bacteria isolated and identified were Lagtghacillns,nlantaznm (3 strains). Lsaiahasillns.hza1is (2 strains), and Lapla- hagillyg,£gzm§nti (16 strains). The thermal death time deter- minations of Wins Ismail. Wins. Mania. and Lagtghggillg§,plantgzum_in phOSphate buffer at pH 7.0 showed that Lactghagilln§_£gzmgnti,was the most heat resistant (F160 - 2.5) of the three species. The heat tolerance of Wine 11291.11 (F160 .. 1.19) and Wins nlanimm (F160 - 1.08) were not greatly different. Bobbins' (23) determined the effect of several concen- trations of sucrose on the growth and thermal death times of Lag;2hagillua,£gzm§nti. Sucrose solutions of 30 and 50 per- cent were found to have a lethal effect upon the organism,' even at toom temperature. However, solutions of 15 and 25 percent had no significant effect at room temperature and exerted a great protective action at pasteurizing temper- atures. The Fléovalues for Lactnhagillng {ggmgnti in 15 and 25 percent solutions were h.9 and 6.6 respectively. Addition I 7 of acetic acid to the substrate in which the cells were heat- ed reduced the thermal death time of the organism greatly. The inclusion of 3 percent salt (NaCl) in the solution con- taining 25 percent sucrose and 1.0 percent acid had no meas- urable effect on the thermal death time of Lagtghagillng {filmfinllm This information may prove of value in suggesting wheth- er any protection is afforded microorganisms during process- ing of sweet, fresh cucumber pickles once the variation of soluble solids concentration has been determined throughout the pack, during processing. In addition the following may serve as an indication to what goes on during equalization in syrup packed products and the effect stratification may have on the product itself. The literature provides information in the area of drained weight studies which is of some value to the present problem. Bitting (5) gives for several fruits the relationship between original concentration of sugar and the final concen- tration after canning and storage, at 30 and 120 to 180 days. Percent soluble solids (Brix) readings of the syrup showed little difference at these two storage times. He pointed out that the most marked decrease in weight of fruit is apparent- ly shortly after processing. Further, it was found that the high weight for fruit and low weight for syrup occurred at the longest storage time of 120 to 180 days. It was stated that a gradual increase of water in syrup and sugar in the 8 fruit continues until equalization. The time required to reach equalization and the rate or extent of changes occur- ring during equalization was not determined. Leonard, Luh, and Mrak (18) found that the drained weight of canned peaches was at a minimum in the ”day-after” (day after canning) out out. It was suggested that the drain- ed weight falls below the filling weight because fluid from peach tissue is lost to the sugar syrup as a result of the concentration gradient difference. On storage the weight of peach tissue increases again because of sugar penetration into the fruit. They stated that, ”the time required to reach equalization of all the constituents between the cover syrup and the peach tissue was controlled by the concentration gradient, mobility of the moving molecules, and resistance offered by the peach tissue.” Adams (1), Bedford and Robert- son (3). and Ross (2h) found cherries reached their minimum drained weight 3 days after canning. These drained weight studies indicate that the permeability of individual products affects product—liquid interchanges when canned in sugar sol- utions. Ross (2“) investigated the translocation of sugars and water in canned fruits. The drained weights of fruit and syrup were determined, than the percent soluble solids (Brix) of the blended fruit and a sample from the drained syrup was determined. The percentages of soluble solids thus obtained reflect average values for the containers evaluated. The results indicated a rapid movement of sugar into the fruit. 9 The high initial osmotic pressure in the cover syrup was believed responsible for the rapid movement of water into the syrup. Hughes, Chichester, and Sterling (1h) have recently investigated the penetration of maltosaccharides into heat processed Clingstone peaches. The rate of sugar penetration into peach tissue was related directly to the concentration and inversely related to the degree of polymerization or size of the sugar molecule. Cruess (9) states that, “the changes in composition of the syrup are due to osmosis.” He also reports that in most fruits this change occurs without shriveling or without burst- ing of the fruit, although fruits with tough skins, such as grapes, may burst in very dilute syrup and shrivel in a heavy syrup. Bitting (5) reported that fruit which is very succulent and has little supporting tissue, such as strawberries or raspberries, undergoes heavy shrinkage, depending upon the strength of the syrup used, while a pear, with its stronger supporting tissue, will suffer little change. The work of Adams (1, 13) has indicated that drained weights are lower in over-ripe and over-processed berries (such as canned strawberries, raspberries, blackberries and loganberries) owing to breakdown of fruit structure and to osmotic action of the heavy syrup, causing shrinkage and shriveling which is due to the loss of water by the fruit to the syrup. Soft and ripe fruits interchange their con- lO stituents with the syrup more rapidly than firm, tough- skinned fruits. It is apparent from the literature that many invest- igators have worked in the area where product-induced strat- ification is of importance without observing the presence of such a phenomenon. Now that this phenomenon has been dis- covered it needs to be explained. EXPERIMENTAL PROCEDURE It has been shown by previous investigations that when a sugar (sucrose) solution of high concentration is added to fresh cucumber pickles during a canning Operation, an inter- change of liquids takes place between the product and syrup. This interchange is not uniform throughout the container and a much greater reduction in syrup concentration occurs at the tOp of the container, than at the bottom of the container. The experiments in this project were designed to investigate the details of this interesting phenomenon. Ezsaanaiian_a£_&xzuns_and_azines The syrup was made in approximately 11.“ l. (3.0 gal.) lots; 5.4u kg. (12.0 lb.) of sucrose, 3.05 kg. (6.72 lb.) of lo percent white vinegar (10 percent acetic acid) and 2.30 kg. (5.28 lb.) of water were blended together with an electric mixer untill all of the sugar was dissolved. The prepared syrup was stored in clean gallon jugs. From an ideal stand- point, it would have been more desirable to use only sugar plus water as the syrup; however, the thermal process required to prevent spoilage of cucumbers at their normal pH of about 6.5 would have been so severe that the results would not be applicable to pickle products. The decision was made to use a sugar-acid-water syrup and a heat process comparable to that employed in the normal pasteurization of pickles, 12 Esselen g1,al. (10). In the tests with peaches, no acid was used in making the syrup; however, the normal pH of peaches is such that a long thermal process is not required. A brine containing 20 percent salt was used in a few tests. This brine was prepared by dissolving 0.73 kg. (1.60 lb.) of salt in 2.90 kg. (6.h0 lb.) of water. H2Q21412§1§ Ink-dyed spears were submerged in a sugar syrup in an attempt to observe the syrup-water interchange phenomenon. Three-hundred m1. of standard sugar solution (50 percent sucrose, 2.8 percent acetic acid) was added to one 500 m1. graduate cylinder and 300 m1. of 20 percent brine to a second graduate cylinder. Two cucumber spears were removed from the ink solution in which they had been soaking for 3 days; one was suspended in the center of each graduate (a metal weight heavy enough to overcome buoyancy was hung from the bottom of each spear). The movement of ink-colored cucumber liquid was observed. O A dialyzing membrane approximately 2 inches long and 3/h inch in diameter was filled with ink. The dialyzing membranes full of ink were placed in graduate cylinders as described above and the movement of ink observed. Wm Cucumber spears, cucumber slices, cherries, and peaches were canned in the laboratory to study product-induced 13 stratification. Cucumber_Tasis The cucumbers used in this study were a slicing variety obtained from the Food Store Purchasing Agency at Michigan State University. The cucumbers were grown in southern states and a time lapse of l to 4 days probably occurred between har- vest and receipt at the laboratory. All cucumbers arrived in excellent condition. Cucumbers measuring 3.81 to 5.08 cm. (1-1/2 to 2 in.) in diameter and 15.2b to 20.32 cm. (6 to 8 in.) in length were used. The specific gravities of ten cucum- bers from each of two lots used in the investigation were de- termined. The method of determining specific gravity was to determine the cucumber weight in air and the cucumber volume by submerging in water. Specific gravity was calculated by divid- ing the product of cucumber weight in air and specific gravity of reference liquid (water) by the difference in weight in air and in liquid. The mean Specific gravity for lots_1 and 2 were, respectively, 0.9h0.: 0.006 and 0.936 1 0.010. The average deviation from the mean for the lots was of such magnitude that the lot means overlapped. Thus, there was no significant difference in specific gravity found between lots tested. Cucumber Spears were used in most of the studies; how- ever, some cucumber slices were used in certain phases of the investigation. Cucumber spears were prepared by cutting the cucumber lengthwise into 3, h, or 6 equal wedges (hereafter referred to as cucumber-thirds, cucumber-quarters and 1h cucumber-sixths), after cutting the ends off to obtain a uniform section 10.08 cm. (4-1/8 in.) long (Fig. l). The 0.79 cm. (5/16 in.) slices were prepared using a hand Operet- ed Eagle slicing device. Standard 16-02. (sometimes referred to as a 16-02. veg- table or No. 303 jars) commercial pickle jars with lug clos- ures were used in this investigation. The physical dimen- sions of this container are given by Nicholas, Pflug and Costilow (20). The inside height to the tap of the finish was reported as n-3/u in. The outside diameter, normal fill, and jar weight were, reSpectively, 3 in., 16-02., and 202 g. The packing procedure followed consisted of weighing each jar and then adding 300.0 1,5.0 g. (10.58 3,0.18 oz.) of cucumber spears or slices. A deviation from this weight occurred in one test when 283.5 :_5.0 g. (10.0 1 0.18 oz.) of slices were packed. Since the diameter of the cucumbers varied as previously described, there was a variation in number of Spears or slices necessary to obtain a desired weight. The number of Spears varied from 8 to 11, with 10 spears required for most jars. The number or variation in number of slices per jar was not determined. Packing arrangement for Spears consisted of cucumber skin in toward the jar center and cut surface adjacent to the glass. Slices were packed by making a column of horizon- tal slices and then packing slices vertically about this column. In the first series of tests the average volume of 15 .mamonn nopasoso Sneak .H .wam . o _.. +9.me .n . .. or (. . . s y r .. “(4 J if r . ')..1 't I .; .. emf 16 syrup necessary to fill the jars to 0.h8 cm. (3/16 in.) below the finish was 1&8.0 ml. with a variation of ¢,15.0 ml. The volume of syrup added was fixed at 150.0 ¢_2.0 ml. in tests to determine vertical soluble solids gradient, effect of cut surface area on product-induced stratification, and equal- ization from 0.0h days to 8 days in sweet, fresh cucumber, spear packs. The syrup was at room temperature when added to the jars. The jars of cucumbers were heat processed in an 82.2°C. (180.0°F.) water bath for no.0 minutes and cooled in a cold water (approximately 12.0°C. (5h.O°F.)) Spray for 15 minutes. Jars were stored in closed cases, in a storage room at 23.3 1 l.l°C. (7h.0 :_2.0°F.). Certain tests warranted deviation from these general processing, cooling and storage procedures. Such procedures pertinent to Specific tests will be described in the results. Throughout the investigation, care was taken in the handling of the jars to avoid unnecessary agitation of jar contents. £hszzx.22fil One test was conducted to determine if sugar stratifica- rion occurs in red sour pitted cherries canned with a sugar syrup. Sour cherries of the Montmorency variety were soaked in l0.0°C. (50.0°F.) water for h hours, sorted to remove blemished fruits, and mechanically pitted. A packing weight of 368.6 :_5.0 g. (13.0 i 0.18 oz.) of pitted cherries per 17 jar was used. The cherries were placed in 16-02. jars, covered with syrup (same composition as that used on cucumb- ers) and sealed. The jars of cherries were heat processed in a 82.2°C. (180.0°F.) water bath for 20 minutes and cooled with a cold water (approximately 12.0°C (5b.0°F.)) Spary for 30 minutes. The soluble solids content of the syrup was determined at the top and bottom of 2 jars randomly selected at frequent intervals over a period of 60 days. W Halehaven peaches of Optimum to Slightly green maturity were used to determine if stratification would occur in can- ned peaches. Peach skins were removed by holding peaches in a 1.0 percent sodium hydroxide solution at 100.0°C. (212.0°F.) for 1 minute followed by a cold water spray. The peaches were pitted, cut into h equal wedges and 328.0 :,5.0 g. (11.57 i 0.18 oz.) were weighed into 16-02. jars. The jars were then filled with 129.0 ¢_10.0 ml. of a special syrup (50.0 percent sucrose) and sealed. The jars were heat processed in rapidly boiling water (approximately 100.0°C. (212.0°F.) for 28 minutes and cooled in a cold water (approximately 12.0°C. (54.0°F.)) Spray for 32 minutes. The soluble solids of syrup at the top and bottom of 2 jars selected randomly was determined at frequent intervals over a period of 32 days. 18 MEASUREMENT AND EVALUATION PROCEDURES Salahls.Sslids.£ansanizeiian. The soluble solids concentration was determined with a Baush and Lomb Abbe - 3L double scale refractometer calibrated both for refractive index and soluble solids. The refractive index scale is divided into divisions of 0.0005 making it possible to estimate refractive index to 0.0001. The soluble solids scale which is based upon the 20.0°C. International Sucrose Tables is divided into divisions of 0.2 making it possible to estimate soluble solids to 0.1 percent. The zero of this refractometer was checked at the beginning of this investigation with boiled distilled water and was found to be prOperly zeroed. Twice during the investigation, con- densation hindered visibility of the scale and made reading impossible. The instrument was dried in an oven at 37.8°C. (100.0°F.) for approximately 2h hours. Each time after dry- ing, the zero of the refractometer was re-checked with boiled, distilled water and it was found to be in prOper calibration. These experiments were carried on in a laboratory where the temperature variation over the experimental period of 10 months was 2n.0° to 32.0°c. (75.2° to 89.6°F.). The maximum error in percent soluble solids which could occur due to such a temperature variation (maximum 8.0°C.) is 0.67 percent soluble solids for 50.0 percent sucrose syrup. The refractometer was Operated at room temperature. The ambient temperatures were recorded along with refractometer readings 19 and the readings were later corrected to 20.0°C. The experimental data are reported as percent soluble solids. It was recognized that salt and acid would contribute to the soluble solids readings; however, it would have been almost impossible to carry on this experiment if analysis were made to give actual percent sugar concentration. In the peach test, a syrup containing only 50.0 percent sucrose was used. We: Hypodermic syringes and needles were used to remove syrup samples from the canned products. The following sizes (gauge) and length of needle were used: 1 in. -180; 2 in. -186; 3 in. -15G; h in. -186; and 6 in. -15G. A test was conducted to determine the effect of needle gauge on the percent soluble solids. Since the different sized needles would have different inlet velocities and height of capillary rise, it seemed possible there could be a difference in result due to a sample error as determined in a solution of non-uniform concentration. A plastic con- tainer of rectangular shape (1 in. x 2 in. x h in.) and 130 ml. capacity was half-filled with syrup (50 percent sucrose, 2.8 percent acetic acid). Water was carefully added to finish filling the container. The container was fitted with a cover that made it possible to support the different needles at the same depth in the container. It was possible tO vary this depth. 20 Two series of tests were conducted. In the first series, the samples were taken from the heavy syrup at a height Of l/A-h (1 in. above the bottom). Duplicate samples were taken with the 2 sizes of needles at 1 minute intervals over a period of 3 minutes. Samples at the different intervals cannot be directly compared since the system is dynamic and progessing to an equilibrium. The second series Of tests were made at the syrup-water interface 1/2-h (2 in. above the bot- tom) and samples were taken in a similar manner to the first test. The data from the two tests is presented in Table 1. TABLE 1. EFFECT OF NEEDLE SIZE (GAUGE) ON PERCENT SOLUBLE SOLIDS IN A DYNAMIC SUGAR SOLUTION Needle Heavy syrup (l/u-h) Syrup-water interface (1/2-h) sauss_. l_mini.2_min1.3_mlni. l_min.. 2__min.. 3_minl. 18 “9.73 “9.23 “9.23 10.16 9.56 9.26 15 us.93 h8.53 n7.93 10.16 8.96 8.56 18 u9.61 u9.69 u9.89 11.56 11.16 11.56 15 u9.31 u9.b9 u9.09 11.56 10.u6 11.96 Analysis of the data in Table 1 showed the following: (1) the percent soluble solids of a sample gathered with the 15 guage needle was lower than, or equal, (equal in 2 tests) to the sample withdrawn with the 18 gauge needle in 11 out of 12 tests; (2) the sample Obtained with the 15 gauge needle was lower by an average of 0.5h percent soluble solids for all tests, with a range Of 1.30 to -0.b percent soluble solids; and (3) the average difference due to needle gauge 21 in light and heavy syrup was O.h0 and 0.68 percent soluble solids respectively. It is recognized that there is an average difference of 0.5h percent soluble solids between the readings made with 15 gauge and 18 gauge needles. It would have been desirable to use one size of needle throughout; however, it was not possible to obtain enough needles of one size to carry on the project. The variation between needle size was neglected because this variation was small in relation to the variables measured and an effort was made to consistently use the same needles for sampling in the same location. The use of the 18 gauge needles was restricted to sampling the tap in most tests. W Syrup samples of 0.2 to 0.3 ml. were taken from the tOp (liquid surface) and bottom (approximately 1/16 inch above the jar bottom due to needle flange) of the container. The tOp of the Jar was sampled first, with subsequent sampling of the bottom. Samples were taken from the tOp by merely inserting a l in.-18 gauge needle just far enough into the syrup to obtain a sample. To sample the bottom, a 6 in.-15 gauge needle was inserted adjacent to the Jar and between the product and glass until it touched bottom. This procedure limited agitation of the Jar contents. The procedure des- cribed above was also followed when sampling the syrup of the canned cherries and peaches. The soluble solids content of the cucumber spear at the 22 top and bottom of the container was determined in addition to the soluble solids of the syrup. The procedure followed in sampling was to remove a spear from the Jar, blot to remove adhering syrup and then out a 0.50 cm. (3/16 in.) section from each end. Slices were tested by removing a slice from the tOp and bottom of the jar. The syrup or Juice was ex- pressed from the cucumber pickle onto the refractometer by squeezing between the fingers. A series of tests were made to determine the distribution of soluble solids in l6-oz. Jars of sweet, fresh cucumber spears. The objective of these tests was to provide data at more than two locations in the Jar to base general conclusions regarding the phenomenon under study. In this study both un- heated and heat processed spears were studied. Syrup samples were taken at the center of each quarter section of the Jar, (at distances of 1/2, 1-1/2, 2-1/2, and 3-1/2 inches from the bottom) and at the tap and bottom of the Jar. The posi- tions sampled and needles used were: bottom, 6 in. -15G; 1/2 in. from bottom, h in. -180; 1-1/2 in. from bottom, 3 in. -150; 2-1/2 in. from bottom, 2 in. -18G; 3-1/2 in. from botq tom, 1 in. -180 and tOp, l in. -l8G. The soluble solids concentration of the syrup of unheated sweet cucumber spears was determined at 1, h, 16, and 6h minutes and 2“ hours after adding the syrup. The soluble solids concentration of the syrup of heat processed sweet cucumber spears was determined at 6h minutes and 2h hours after adding the syrup. 23 W A Beckman Model G portable pH meter equipped with "One- DrOp” electrodes was used to determine the pH of syrup taken from the top and bottom of Jars of sweet, fresh cucumber spears. The 0.2 to 0.3 ml. sample described above was suffi- cient to charge the refractometer for determining the soluble solids and the ”One-Drop” electrodes for determining the pH. The pH of 3/16 inch square, 1/8 inch thick portion cut from each end of a sweet cucumber spear was determined by placing this section of product (crushed) into the "One-DrOp” electrode. W The titratable acidity calculated as acetic acid was determined in some of the tests. The procedure for this analysis was as follows: 1. A five m1. hypodermic syringe and the needles des- cribed previously were used to remove a sample containing 5.0 1,0.1 ml. of syrup from the jar of cucumber spears. 2. The sample was deposited in a 125 ml. Erlenmeyer flask and then diluted with approximately 20 ml. of distilled water. 3. One or two drops of phenolphthalein indicator were added to the flask. u. The sample was titrated with approximately 0.1 N standardized sodium hydroxide to the phenolphthalein 2b and point from a 50 ml. burette with 0.1 ml. gradations. 5. The percent acetic acid was calculated using the equation: Acetic acid, = ( percent (m1. of sample) W The appearance, texture, and flavor of sweet, fresh cucumber spears were subjectively evaluated by the author. General appearance both in and out of the jar was eval- uated relative to shrinkage and conformation changes during equalization. Textural differences between the tOp and bottom portions were determined by chewing to evaluate crispness and touching to evaluate softness. The product was taste tested to determine if differences in sugar concentration between the top and bottom portions could be detected. RESULTS This investigation is primarily concerned with the dynamic processes of syrup-product equilibration which results in product-induced stratification, and the possible implications this phenomenon may have on product quality. The results of this investigation are reported according to the following phases of study: (1) Visual studies, (2) Stud- ies on unheated fresh cucumber pickles, (3) Studies on heat processed fresh cucumber pickles, and (4) Studies on product- induced stratification in other products. Mlflnfll_§£ndlfifi Cucumber liquid was found to flow to the surface of the covering liquid when an ink-dyed cucumber Spear was placed in standard syrup (50.0 percent sucrose and 2.8 percent acetic acid) or standard brine (20.0 percent salt (NaCl)). The cucumber liquid moves into the syrup and then immediately rises to the surface in a vertical stream estimated to be 1 mm. in width. There was no appreciable mixing of cucumber liquid (ink-dyed) with the sugar solution except at the tOp surface of the syrup. It was found that even the flow of undyed cucumber liquid in standard syrup could be detected by very close observation. Approximately the same results were observed when a dialyzing membrane containing the dye was submerged in stand- 26 ard syrup or standard brine. When water was placed in a dialyzing membrane and submerged in the standard syrup stratification resulted. S1ndias_an_flnhaalad_££ash_£naumbar_£inkles The soluble solids changes occurring at tOp and bottom of the container due to product-induced stratification in jars of sweet, fresh cucumber spears are presented in Figure 2 and Table 2. TABLE 2. SYRUP SOLUBLE SOLIDS CHANGES IN JARS 0g UNHEATED SWEET, FRESH cucunsss SPEARS Time lapse after adding .Salnbla_salidsi_nszaent sxzuai_minutss Tan. flatten 0.25 51.5 52.1 1 nu.5 51.7 2 02.5 51.7 0 39.h 51.? 8 37.5 51.6 16 35.2 50.8 20 33.1 50.0 no 30.8 #8.6 56 30.1 97.8 6t 29.8 u6.9 128 2u.5 03.2 1Average data from h jars at each sampling time. It can be observed from Figure 2 that the soluble solids concentration at the t0p changes more rapidly than at the bottom; the soluble solids concentration at the tap decreases 9.0 percent in 2 minutes while the bottom decreases only 0.0 . .mamonm meniscus Scope .pemSm cannons: no when a« mowsmso meaaom cansaom asahm .N .mam $52.: $35 e259 5:4 mmmfi m2: 2? Ox. 00 On O¢ on ON .0. _ «a Q05. (A — $5..me : q (D C) m N insoaad ‘sonos 3190105 C) Q‘ 28 percent in 2 minutes. EVeu at 128 minutes the top and bot- tom percents were still decreasing and the difference between tOp and bottom was still increasing. The soluble solids con- centration at 128 minutes was 20.5 percent at the top and 03.2 percent at the bottom, a difference in concentration of 18.7 percent. Figure 3 and Table 3 Show the results of the test to determine the vertical soluble solids gradient in jars of sweet, fresh cucumber spears (soluble solids measured at 6 positions in the jar). These data are in general agreement with those of the first test reported in Table 2. TABLE 3. SYRUP SOLUBLE SOLIDS GRADIENT IN JARS 9F UNHEATED SWEET, FRESH CUCUMBER SPEARS Position, inches from ____.__.Salahla_Salidsi_nernsnt__________. .__hnttnm___. l_min.. &_min1. l§_minl. §&_min.. 2&_nnsl 0.0 (Top) 00.7 01.1 36.0 30.7 15.2 3.5 50.8 09.1 03.1 37.5 17.6 2.5 51.2 50.5 06.0 38.2 19.1 1.5 51.2 50.9 08.9 02.2 23.9 0.5 51.1 51.3 50.7 06.5 35.3 0.0 51.1 51.1 50.7 08.6 01.0 A. 1Average data from 2 jars at each sampling time and position. The results of a test to determine the effect of cut surface area on product-induced stratification are presented in Figure 0 and Table 0. The data indicate that cucumber- quarters brought about the most rapid stratification and cucumber slices the least rapid. The stratification rates SOLUB LE SOLIDS , PERCENT 29 5° I I I g 4 MIN. 50 “V -— 1 - 1 - l _ '00 . I 2 3 4 POSITION, INCHES FROM BOTTOM Fig. 3. Syrup soluble solids gradient in jars of unheated sweet, fresh cucumber spears. 3O .mxomq nonssoso gnome .uoozm condoms: you mmofim 0 I mIanIm—dflam 4 e o momiklmdflam mmm...m<30l mm 02.004 Kuhn? mmm<4 m2; 10130330 ‘scnos 3180108 ' m e s . m . m . e. m N _ o a _ . _ _ q _ _ A u [m mos fin.. zossom r as panacea a oam>m o. _ _ h _. _ _ _ om 37 difference in pH between top and bottom of the syrup (0.62 pH difference) and product (0.50 pH difference) occurred at the first sampling which was made 60 minutes after the syrup was poured on the product. There is an apparent trend for this difference to decrease as one approaches the last samp- ling which was 8 days after adding the syrup. TABLE 8. pH CHANGES IN SYRUP AND CUCUM ER SPEARS AFTER HEAT PROCESSING Time lapse DH after adding Syrup _______£xgfiugt:, WMMWMMW 0.00 3.93 3.31 0.62 0.13 3.59 0.50 l 0.06 3.50 0.52 0.11 3.69 0.02 2 0.02 3.60 0.02 0.05 3.66 0.39 0 0.09 3.70 0.39 0.03 3.73 0.30 6 0.03 3.73 0.30 0.07 3.75 0.32 8 0.02 3.71 0.31 0.00 3.75 0.29 1Average data from 3 jars at each sampling time. Changes in percent acetic acid at the tOp and bottom of the covering syrup are presented in Figure 8 and Table 9. The greatest difference in percent acetic acid between the top and bottom occurred at the first sampling which was 60 minutes after the syrup was poured on the product. Acetic acid equalization between the tOp and bottom proceeds as the time approaches 8 days, but is not reached at 8 days. . . .mxema Amman nonasoso smash..pomzm commoooan amen ad Sasha mo owam£e oaom oauoe< .m .Mam was warm ezao< mmta mmoj mac. J 38 _, N 1N3083d s, e m o e m N . . o _ _. . _ . q H A _ .. mos . z 0 [0) 0 L01 Lu. J. . .0 22.2.8 — _ _ h _ — p M "Olav Oliaov 39 TABLE 9. SYRUP ACETIC ACID CHANGES IN HEAT PROC SED SWEET, FRESH CUCUMBER SPEAR PACKS ~— Time lapse after adding et ~ 1 e t2 sxznnl_dsls_ Tan. Bottom 0.00 1.07 2.56 1 1.05 2.07 2 1.00 1.91 1'" 1009 1.81 6 1.08 1.71 8 1.13 1.70 1Average data from 3 jars at each sampling time. 2Percent acetic acid by volume. The results of tests to determine the time required to reach equilibrium throughout the container are presented in Tables 10, 11, 12 and illustrated graphically in Figures 9. 10, and 11. Figure 9 and Table 10 show the time required for equal- ization of soluble solids throughout the covering syrup and cucumber spears. TABLE 10. SYRUP-PRODUCT SOLUBLE SOLIDS EQUILIBRATION IN 1 HEAT PROCESSED SWEET, FRESH CUCUMBER SPEAR PACKS Time lapse ___S913h1£_flflllfi£4_n§£Q§nL—— after adding Syzup zzggngg filiflfla.flfll§_. IRE. 5932. ‘T92. 5911. 0.00 27.6 00.1 9.6 17.5 1 17.0 37.9 10.2 28.6 2 16.0 37.2 10.7 29.3 0 16.0 33.6 15.9 28.7 8 15.3 32.5 15.0 30.3 16 16.7 29.7 16.7 29.0 32 18.0 25.9 18.2 27.0 60 19.8 23.2 20.0 23.3 128 20.6 21.6 21.5 22.3 213 21.1 21.6 22.2 22.3 1Average data from 6 jars at each sampling time. .mxoma ammmm nonasoso cmoam .poozm commoooan use: ad acapmnndadovo meadow OHDSHOm posconnlmsnhm .m .wdm 00 «:3 .m2: com 8. on o. m _ 6.0 _.o 8.0 . .oo _ _ . _ _ _ _ q r .0. do» I 4 4 ION .. . o . . Ion sotbm 4 I _ .9. .356 o d sonoomo o o _ _ _ _ _ _ _ _ on SOI‘IOS 3180108 0 1N3083d 01 Syrup-product soluble solids changes during equalization for sweet, fresh cucumber slice packs are presented in Figure 10 and Table 11. The data indicate that the maximum product- _ induced stratification in both the syrup and slices occurs at 1 day. TABLE 11. SYRUP-PRODUCT SOLUBLE SOLIDS EQUILIBRATION IN HEAT PROCESSED SWEET, FRESH CUCUMBER SLICE PACKS1 Time lapse , _ 5913111.:an after adding __anun____ __£radact__ eranl_daxs_. Tan. Est; 199 DEL. 0.00 20.7 02.7 16.2 19.2 1 18.1 39.0 13.8 30.2 2 20.2 00.3 20.3 33.2 0 17.9 30.3 17.6 33.6 8 19.6 30.0 19.0 29.0 16 18.0 31.2 18.2 31.1 32 18.6 26.6 18.7 26.6 60 22.0 25.0 22.3 25.0 128 22.8 23.3 23.3 20.2 213 ' 23.8 20.0 20.0 20.3 1Data from 1 jar at each sampling time. Figure 11 and Table 12 show the changes in percent acetic acid at top and bottom of the container throughout equalization (0.00 days to 128 days). The data are presented separately from the test above covering early stages of equal- ization since the former test only includes 8 days, also in the former test the volume of syrup was fixed at 150.0 :_ 2.0 m1. while in the latter longer equalization test the syrup volume was 108.0 1 15.0 ml. Equalization of acetic acid in syrup samples taken from top and bottom of the container occurred at approximately 60 days. 02 .mxomm madam aonezoso sneak .poozm commoooan 9mm: :« soapmanaaasum meadow canzaom uosooaanmznhm .OH .mam . «.55 as: _ _ 00m 00. On .0. m _ ad _.o 00.0 5.0 _ _ _ _ . _ _ _ _ 1 .o. s nu m Mn. an 1. I . .8 3 cu 0 . . n nu Cu I Ion. .d .1 nu «a ad N" I d 10101 d3m>m 4 c , .5300?“ O o _ _ b _ _ _ _ _ Om 43' .mxemg amomm nonssoso among .pmmzm commenced amen a“ manna mo ceapmmnaaasve odes cameom .HH .wdm . $40 .52: 00m 00. on o. m _ .06 _.o no.0 5.0 a q _ _ a _ _ a . I I. do... 0 O ... NI!” no I r 22.5w N . nu _ _ _ p _ _ L "Olav 0I130v lNBOH 3d 00 TABLE 12. SYRUP ACETIC ACID EQUILIBRATION IN HEAT PROCESSED SWEET, FRESH CUCUMBER SPEAR PACKS Time lapse after adding et d an 2 fi¥2221_flfilfi_. Tan EQLLQT 0.00 1.33 2.82 1 1.12 2.23 2 1.114 20“]. 0 1.18 1.98 8 1.17 1.90 16 1.30 1.71 32 1.07 1.53 60 1.08 1.07 128 1.08 1.05 :Average data from 3 jars at each sampling time. Percent acetic acid by volume. .0 ‘ no ' co - Q... Se .. 400‘ P09, The results of the test to determine if product-induced stratification occurs when red sour pitted cherries and peaches are packed with a heavy syrup are presented in Figure 12 and Table 13. TABLE 13. SOLUBLE SOLIDS CHANGES OF SYRUP IN JARS OF HEAT PROCESSED RED SOUR FITTED CHERRIES AND PEACHES Time lapse ‘ after adding Snur_£hsmziss. Beaches sxnnai_dala. Tan. 2211. Tan. BELL 0.00 26.7 00.8 27.0 01.2 1 19.7 01.0 18.7 39.0 3 19.5 36.3 17.9 36.1 6 20.0 32.8 18.3 32.6 16 20.8 29.1. 19.9 28.3 32 ---- ---- 20.0 26.0 60 22.5 26.5 ---- ---- 1Average data from 2 jars for each product and sampling time. ’45 .mmnemon can modano£e emppaa . I soon eon commenced can: no mama ad asahm no mowsmno meadow capsaom .NH .wum . min .22: com _ 8. on o. o _ no 8 mod .06 J _ _ 1 q _ q 0 J. I no. dos I ION I .6» soFFOm I Ioe $3.55 4 4 muzo