• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.137-143
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• 1987

To find out the optimum storage temperature and duration, changes in the content of sugars and soluble solids and flavor rate of two sweet corn hybrids (Great Bell and Golden Cross Bantam) and a super sweet corn (Crisp Super Sweet 720) were observed after storing at -20, 0, 5, 10, 15, 20, and 25$^{\circ}C$ for 1,3,5, and 7 days. At the temperatures below 10$^{\circ}C$, contents of soluble solids and total sugars and flavor rate were not changed significantly, but at the temperatures higher than 15$^{\circ}C$ they decreased as storage temperatures increased and duration extended. Storage duration conserving flavor seems to be 7 days at temperatures below 10$^{\circ}C$, 3 days at 15$^{\circ}C$, and 1-2 days at 25$^{\circ}C$. When corn was frozen, flavor rate was a little low compared with corn stored at 0$^{\circ}C$ although sugar content was higher. Both soluble solids and total sugar contents were positively correlated with flavor rate of cooked corn.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.500-505
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• 1985

A method to store concentrated milk in the liquid state at $-15^{\circ}C$ was developed, and quality changes during storage of milk were evaluated. Combined cryoprotectants (CCP) suitable for storing concentrated milk in the liquid state at $-15^{\circ}C$ were consisted of 17.74% sucrose, 8.87% glucose, 8.87% fructose, 2% glycerol, 0.25% sodium hexametaphosphate, 0.25% NaCl and 0.02% ascorbic acid. The amount of CCP to be added to concentrated milk to depress freezing point to $-15^{\circ}C$ was 38% by weight. Gelation due to protein denaturation was the most serious quality change during storage, which adversely affected appearance and utilization of the stored product. Gelation was observed after 3 weeks storage in the control, but it was not in milk with CCP throughout 18 weeks storage. Amount of protein precipitated increased in the control during storage, whereas there was no protein precipitated in milk with CCP. Surface color and peroxide value of the control and treatment did not change significantly during storage, and there were no marked differences between the control and treatment. These results indicated that quality of concentrated milk could be preserved, without gelation, by storing milk with CCP in the -liquid state at the frozen storage temperature. Besides, energy required for freezing preservation of milk could be significantly reduced by elimination of phase changes for freezing and thawing, and the stored product could be continuously processed for the final products without long waiting time for thawing.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.211-218
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• 2018

Different packaging methods and storage temperatures were tested to determine the storage stability of beef dry-aged for 21 days based on microbial, physicochemical, and sensory qualities. After completion of the dry aging, the dried surface of beef sirloin was trimmed off, and the beef was packaged using two different methods (oxygen-permeable wrap or vacuum packaging) and stored at different temperatures ($3{\pm}2^{\circ}C$ or $-23{\pm}2^{\circ}C$) for 0, 7, 14, or 21 days. Lipid oxidation and the sensory quality of the dry-aged beef were not affected by the packaging method and storage temperature during storage. No microbial growth was observed over the storage period in the vacuum-packaged dry-aged beef, regardless of the storage temperature. However, dry-aged beef in the oxygen-permeable wrap packaging showed microbial spoilage with 8.82 log CFU / g at day 7 of the refrigerated storage. The vacuum-packaged dry-aged beef showed the lowest values (p < 0.05) in $a^*$ and chroma at days 14 and 21 at $3^{\circ}C$, and days 7 and 14 at $-23^{\circ}C$, respectively. Therefore, it is recommended that dry-aged beef with wrap packaging stored in refrigerated conditions should be consumed as quickly as possible due to microbial growth. For long-term storage, dry-aged beef should be frozen because freezing can extend the color stability up to day 21 of storage without adverse effects on the hygienic or meat quality aspects of dry-aged beef.

• Food Science and Preservation
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• v.14 no.3
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• pp.227-232
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• 2007

The development of an effective long-term storage protocol for harvested fresh pepper is urgently required to increase the market for pepper products. The protocol must minimize quality loss, so that the product may be used either as a spice or as a raw material for processed pepper products, both in the home and in food processing plants. We investigated the optimum size of pepper fruits, freezing temperatures, storage periods, and thawing methods, to establish an optimum storage protocol. This study was conducted not only to develop freezing and thawing methods for long term storage of harvested red pepper, but also to develop processed pepper products utilizing the stored pepper. We aimed to expand the pepper products market and to increase the incomes of pepper growers. Whole red pepper, sliced red pepper, and crushed red pepper were frozen and stored at $-5^{\circ}C,\;-20^{\circ}C,\;or\;-40^{\circ}C$. The soluble solid content and the vitamin C level showed maximal stability at $-40^{\circ}C$, although total free sugars decreased on storage at all temperatures tested. Such Changes were more marked at $-5^{\circ}C$ than at the other(lower) temperature tested. The vitamin C content of whole red pepper was higher than that of sliced red pepper or crushed red pepper. Room-temperature thawing resulted in twice the drip loss seen on low temperature($5^{\circ}C$) thawing or microwave oven thawing. Brown discoloration was a serious problem with room temperature thawing. Total free sugars were higher in samples thawed at low temperature or in the microwave oven, compared to the level seen after room-temperature thawing. pepper samples thawed at low temperature scored higher in sensory tests than samples thawed at room temperature.

• Korean Journal of Agricultural Science
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• v.43 no.5
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• pp.788-793
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• 2016

Post-weaning diarrhea (PWD), mostly caused by enterotoxigenic Escherichia coli (ETEC), remains to be a major source of economic loss in swine industry. The use of the ETEC-oral challenge model is often applied to mimic unsanitary commercial swine farm conditions where pathogens and unknown complex microbes exist and can cause severe infections in pigs. The purpose of this study was (1) to estimate ETEC density using spectrophotometric computation, (2) to determine survivability of ETEC after storing at $-20^{\circ}C$ for 7 days, and (3) to evaluate survivability of ETEC after blending with diluted sweeteners (0, 5, 10, 20, and 40% sucrose in phosphate buffered saline [PBS]). Cell density was quantified using UV-VIS spectrophotometer and counting ETEC colony forming units (cfu) at 0, 30, 60, 90, 120, 150, 180, 210, and 240 min. The established linear equation ($y=0.0031x^2-0.0079x+0.0043$ and $y=0.0046x^2-0.0151x+0.0113$) was used for robust quantification of each ETEC cell density. ETEC stored at $-20^{\circ}C$ showed 108 cfu/mL after thawing and incubation. When ETEC was blended with sweeteners (20 and 40%), survival of ETEC was decreased by 58 and 54% in 5 min post blending. However, addition of 20% of sweetener resulted in a higher survivability than those with other media concentrations. Therefore, the use of ETEC-oral challenge model would be possible as a stable method if we could confirm the appropriate medium that increases survivability of ETEC in weaner pigs.

• Food Science of Animal Resources
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• v.35 no.6
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• pp.793-799
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• 2015

The market sales of premium ice cream have paralleled the growth in consumer desire for rich flavor and taste. Storage temperature is a major consideration in preserving the quality attributes of premium ice cream products for both the manufacturer and retailers during prolonged storage. We investigated the effect of storage temperature (−18℃, −30℃, −50℃, and −70℃) and storage times, up to 52 wk, on the quality attributes of premium ice cream. Quality attributes tested included ice crystal size, air cell size, melting resistance, and color. Ice crystal size increased from 40.3 µm to 100.1 µm after 52 wk of storage at −18℃. When ice cream samples were stored at −50℃ or −70℃, ice crystal size slightly increased from 40.3 µm to 57-58 µm. Initial air cell size increased from 37.1 µm to 87.7 µm after storage at −18℃ for 52 wk. However, for storage temperatures of −50℃ and −70℃, air cell size increased only slightly from 37.1 µm to 46-47 µm. Low storage temperature (−50℃ and −70℃) resulted in better melt resistance and minimized color changes in comparison to high temperature storage (−18℃ and −30℃). In our study, quality changes in premium ice cream were gradually minimized according to decrease in storage temperature up to−50℃. No significant beneficial effect of −70℃ storage was found in quality attributes. In the scope of our experiment, we recommend a storage temperature of −50℃ to preserve the quality attributes of premium ice cream.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.410-413
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• 1991

Prefried chicken patties were irradiated at dose levels of 0, 2, and 4 kGy using $Co^{60}$ source and stored at $3{\pm}1^{\circ}C$ and $-10{\pm}1^{\circ}C$, separately for the evaluation of color and sensory characteristics. Irradiation dose of 4 kGy slightly darkened the internal color of chicken patties. Except for the internal portion of the frozen samples, an increase (p<0.05) in Hunter 'L' values was observed for both the surface and interior of patties during storage. Upon refrigerated storage, Hunter 'a' values, both on the surface and internally, decreased as the storage period progressed. Only storage period affected (p<0.05) the Hunter 'b' values of patty surfaces and interiors. No difference (p<0.05) in odor, taste, color, and texture of the patties was observed for irradiation dose and storage period as evaluated by triangle tests except between 2 kGy and 4 kGy irradiated samples before forzen storage.

• Food Science of Animal Resources
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• v.18 no.2
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• pp.176-184
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• 1998

The objective of this study was to investigate the effects of freezing rate on aroma retention and to examine the mechanism of aroma retention during freeze drying process. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80${\times}$20mm) containing diacetyl(2mg/ml) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom measured and diacetly contents. Besides, we observed the effect of the relative humidity of the diacetyl contents freeze-dried gelatin during storage. The retained diacetyl content was increased at high freezing temperature and in order of 0∼5, 5∼10, 10∼15, 15∼20 mm section from the bottom of the sample. It was observed that the retained diacetyl content was high in 15∼20 mm section. The retained diacetyl content and freeze-dried gelatin stored in the condition of high relative humidity was decreased significantly but in the low relative humidity case, was it decreased in small amount. The results of our experiment resents that the low temperature freezing and low humidity storing condition is effective for preserving aroma compound in food.

• Journal of Nutrition and Health
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• v.10 no.2
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• pp.27-34
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• 1977

The present study was carried out to evaluate the nutritional quality of rabbit meat protein. The composition of amino acids contained in rabbit meat was compared with those of other animal meats such as beef, pork and chicken. Also included in this study was the question whether the cooking and storage conditions affect the amino acid composition and the pepsindigestibility of rabbit meat protein. The results are summarized as follows: 1. The large variation observed from sample to sample of EAA (essential amino acid) composition in rabbit meat was found to be an interesting but peculiar property of rabbit meat protein. The most limiting amino acid of rabbit meat protein was phenylalanine, whereas methionine was the first limiting amino acid of both beef and pork proteins. Chemical scores of various meat proteins were 68, 65, 66, and 74 for rabbit meat, beef, pork, and chicken respectively. 2. In pan roasting, the EAA damaged most by heat was methionine (15%). When cooked after two months of frozen storage, lysine decreased most. 3. Higher pepsin digestibility was obtained by cooking rabbit meat after seasoned in alcohol, ginger juice, and other spices compared with various other cooking conditions without seasoning. The pepsin digestibility value was even higher for the seasoned meat than for the raw meat. 4. Among various meats tested the rabbit meat showed the lowest pepsin digestibility. 5. A simple measurement of released methionine could be used to determine relative digestibility instead of measuring $NH_2-N$ content after pepsin digestion. From all the results obtained in this study it can be concluded that rabbit meat is a good Protein food item when used fresh and stored properly to prevent rancidity problems. It is suggested to study further the peroxidation effect of unsaturated fatty acids on protein quality. This study was supported by the Ministry of Science and Technology in Korea.

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.155-161
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• 1990

Frozen, prefried chicken breast meat patties and nuggets were obtained from a commercial plant. The samples were packaged with and without vacuum in pouches and stored at $2-4^{\circ}C$. The quality of these products was measured at 4-day intervals for a period of 28 days. Vacuum packaging did not inhibit or reduce psychrotrophic microbial growth of the patty and nugget samples upon refrigerated storage. Log total fungal counts for vacuum packaged samples remained stationary after reaching a log number of 3.5, while a continuous increase was observed for nonvacuum packaged samples. Vacuum packaging did not prevent an increase of TBA values. Free fatty acid values of the samples were low and remained low throughout the observation period. A continuous darkening of the Internal portions of the samples was observed.