• Food Science of Animal Resources
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• v.32 no.1
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• pp.98-102
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• 2012

The aim of this study was to investigate the relationship between a simple method for measuring lipid peroxidation by using a chemiluminescence analyzer and traditional methods, such as 2-thiobarbituric acid reactive substances or peroxide value of solid food samples. Freeze-dried egg yolk powder was kept on $25^{\circ}C$, under dark condition. The peroxidation value was measured during certain storage period by using 3 methods, and the chemiluminescence value was compared with 2-thiobarbituric acid reactive substances or peroxide value. For comparison, 3 kinds of freeze-dried egg yolk were prepared from whole eggs purchased from a local market. The chemiluminescence value was significantly correlated with both the peroxide value and the 2-thiobarbituric acid related substances during storage, and showed a high correlation to the real sample test. It showed a little higher correlation with peroxide value. These results suggest that using a chemiluminescence analyzer may provide the ability to measure the lipid peroxidation of high lipid content solid-food samples, instead performing both the 2-thiobarbituric acid reactive substances test and measuring the peroxide value.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.805-810
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• 2002

Development of tenderizer using domestic fruits was studied. Kiwifruit was dried using various methods, and the quality of kiwifruit powder was observed during 12 week storage. Frozen kiwifruit was prepared in paste, dice, and whole flesh. After drying, paste-type kiwifruit showed 2.0 and 1.3 times higher proteolytic activity than dice and whole flesh kiwifruits, respectively. Nine hour of hot-air drying or 46 h of freeze-drying eliminated more than 90% of water from kiwifruit, during which discoloring of kiwifruit occurred. Freeze-dried powder showed 6.6 times higher yield and proteolytic activity, and resulted in almost no discolorization than those of air-dried powder. Addition of bulking agent affected the quality of hot air-dried kiwifruit powder, except color, resulting in $3.2{\sim}3.6$ times higher proteolytic activity than that without bulking agent, which is comparable to 60% of the initial freeze-dried powder content. Moisture content of kiwifruit powder with bulking agent sustained consistently during 12 week storage, whereas proteolytic activity decreased for the first 4 weeks. Freeze-drying is a preferable method to produce kiwifruit powder for tenderizer, although hot air-drying with bulking agent treatment is more economical.

• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.231-238
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• 1987

Two kinds of soy pastes with different colors (reddish brown and yellowish white) were dehydrated by freeze drying in powder form. Hygroscopic behaviors of powdered soy pastes were investigated under the conditions of various water acitivities (0.11-0.88) and three different temperatures (25,40 and $50^{\circ}C$), and presented a kinetic and thermodynamic interpretatons in the view point of qualities and storage stability. Moisture absorption isotherms of powdered soy pastes were of type II according with BET classification and can be described by the Henderson's empirical equation. The safe storage moisture levels calculated by the Laurie's equation were ranging from 5.5 to 3.98% dry basis with oaring temperatures. The moisture absorption process for powdered soy paste followed the Ist order kinetic in the difference of equilibrium moisture content and arbitrary moisture content and the initial step was characterized by very fast absorption of moisture. The change of, dispersion capacity and color difference for powdered soy paste were extremely dependent upon water activity under the storage and the maximum stability was found at safe storage moisture levels. Also, the variation of thermodynamic parameters with moisture content was significant at safe storage moisture content levels and suggested d the considerable correspondence to storage stability of powdered soy paste.

• Food Science and Preservation
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• v.5 no.4
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• pp.326-330
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• 1998

Freeze storage technique is widely used for food processing to keep freshness and quality of the product. This technique was applied to fresh, unshelled groundnut to develop a new type of product which could maintain fresh taste and nutritive values even after several months of storage. The groundnut varieties, Daepungtangkong, Daekwangtangkong and Sindaekwangtangkong were grown at the experimental field of NCES in 1996. Immatured pods or groundnut were harvested around 20 to 3o days before full maturity, washed, and steamed at 100$^{\circ}C$ for 5 min. to stop enzyme activity. After vacuum packing (at -760mmHg for 10 min.) with 0.08mm polyvinyldichloride film, the pods were immediately frozen at -70$^{\circ}C$ for 24h and transfered at -20$^{\circ}C$ for long-term storage. Physico-chemical properties of frozen vegetable groundnut were investigated at 2 months after storage and compared to those of conventionally dried groundnut. After 2 months storage, the thawed kernels were very palatable with softness and fresh taste. Acid value and hardness (measured as the compression force on the probe of a texture analyzer) were much lower in frozen vegetable groundnut than those in the air-dried ones. Presence of free sugars is one of the important factors affecting groundnut taste, and the free sugar contents were considerably decreased in the frozen vegetable groundnut compared to freshly harvested groundnut. But in dried groundnut no free sugar was detected.

• Food Science and Preservation
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• v.22 no.2
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• pp.167-173
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• 2015

This study was conducted to evaluate effect of adding cryoprotectant agents on the growth of lactic acid bacteria during storage of powdered Kimchi. Powdered Kimchi was prepared by adding 1.5% cryoprotectant (glucose, maltose, lactose, and sucrose) and freeze-dried. For the preparation of micro-sized particle of Kimchi powder, the freeze-dried Kimchi was powered at 14,000 rpm for 2 min. The survival ratio of lactic acid bacteria in the powdered Kimchi was monitored during storage period of 4 months at -20, 0, 4, and $25^{\circ}C$ after the capsulation of the powedered Kimchi. The number of lactic acid bacteria in the powdered Kimchi capsule was the greatest stored at $-20^{\circ}C$, and the addition of glucose in cryoprotectant showed higher survival rate of lactic acid bacteria than that of control. More than $10^7CFU/g$ of lactic acid bacteria were survived in the powdered Kimchi stored at 0 and $4^{\circ}C$. However, the lactic acid bacteria were not detected in the powdered Kimchi stored at $25^{\circ}C$. As a results, the addition of cryoprotectant agents in the manufacturing process improved the survival rate of lactic acid bacteria in powered Kimchi products with accompanying with a cold-chain system for the distributon of powdered Kimchi products.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.451-457
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• 1996

The effects of pH and L-cysteine HCI on the growth and stability of Biofidobacterium breve were studied. Significantly higher population was obtained by culturing at pH $6.0{\sim}6.5$ than at any other pH. The cultures that had been grown at pH $5.5{\sim}6.0$ were more stable during storage than those grown at other pH. The number of B. breve that had been grown at pH 5.5 and 6.0 remained as $2.4{\times}10^6ml/\;and\;1.4{\times}10^6ml,$ respectively, after 25 days of storage at $4^{\circ}C$. The ${\beta}$-galactosidase activity of B. breve grown at pH 5.5 and 6.0 was reduced only to $78{\sim}85%$ of the control after the same storage condition, whereas the culture grown at pH 7.0 exhibited a signficant decline in population and ${\beta}$-galactosidase activity during $4^{\circ}C$. The growth of B. breve was promoted by 0.05% L-cysteine HCI, and cells grown in MRS with $0.05{\sim}0.10%$ L-cysteine HCI were more resistant to hydrogen peroxide. With respect to the effect to the effect of osmoprotectants on the survival of B. breve subjected to freeze-drying, addition of 2 mM betaine of 2 mM trehalose increased the growth rate of cells grown under osmotic stress and also made the organism more osmotolerant. Furthermore, the betaine or trehalose increased the survivability of the cells after freeze-drying.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.517-522
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• 2005

A cold storage refrigerator using phase change material(PCM) has been developed and its performance test results are provided here. The inner temperature of the refrigerator is controlled with forced convection driven by a fan using a DC battery. At the first, to freeze all the PCM of the ambient temperature by a built-in refrigerating machine, it took about 8 and 10 hours respectively at the refrigerator and the freezer mode. Then, without external power supply, the inner temperature of the cold storage refrigerator has been maintained at $-18{\pm}1^{\circ}C$ during 14 hours at the freezer mode and maintained at $3{\pm}^{\circ}C$ during 34 hours at the refrigerator mode. Just after the end of its valid usage as a refrigerator or a freezer, it took about 6 hours to refreeze the PCM for its reuse. During the test, the ambient temperature was kept at $30^{\circ}C$.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.1023-1029
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• 2016

Probiotic functional foods are known to have various functional effects such as intestinal regulation, modulation of immune system, reduction of allergies, and lowering of cholesterol. The purpose of this study was to select probiotic strain that is most suitable for freeze-dried coffee for the development of functional coffee products. The survival rate of probiotics, at drinking condition of coffee, at acid, at bile and after freeze-dried in coffee were measured on 1 strain isolated from commercial freeze-dried coffee, 8 strains used as fermented milk starter, 1 Bifidobacterium and 1 Bacillus coagulans. Bacillus coagulans showed the highest survival rate from $2.4{\times}10^7cfu/g$ to $2.0{\times}10^7cfu/g$ especially after freeze-drying. The results at drinking condition of coffee, at acid tolerance, at bile tolerance and at storage test showed significantly better survival rate of Bacillus coagulans than that of control (Lactobacillus casei). Especially, Bacillus coagulans showed 3.8-fold higher survival rate at acid tolerance (pH 1, 120 minutes) than control. Thus, the lactic acid-producing Bacillus coagulans is characterized as a probiotic strain suitable for functional coffee formulation and commercialization.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.24-29
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• 2002

The study was performed to investigate the degrees of gelatinization at various processing steps during the preparation of Dangmyuns using sweet potato, potato, corn and tapioca starches, and also determined the rehydration of the freeze dried sweet potato Dangmyun. The degrees of gelatinization after extrusion cooking showed higher value than other processing steps. The degrees of gelatinization after extrusion cooking were 63.5% in sweet potato, 80.0% in potato, 82.3% in corn, and 86.5% in tapioca Dangmyuns. The degree of gelatinization in Dangmyuns after extrusion cooking step decreased as the processing steps, such as cold storage, freezing, thawing, and sun drying, progressed. L values of color in Dangmyuns decreased in the order of corn>tapioca>potato>sweet potato Dangmyuns. The cooking loss decreased in the order of tapioca>corn>potato>sweet potato Dangmyuns. The percentage of weight gain was the highest in sweet potato Dangmyun followed by corn, potato, and tapioca Dangmyuns. The water absorption rate constant was the highest in sweet potato Dangmyun followed by corn, potato, and tapioca Dangmyuns. In the rehydration of freeze dried Dangmyuns, freeze dried sweet potato Dangmyun showed better than the others. An increase from 60% to 70% of the added amount of water in the mixing step resulted in an increase of the degrees of gelatinization after extrusion cooking from $63.4{\sim}70.7%$ to $73.8{\sim}75.0%$. An increase of the added water in the mixing step and a decrease of diameter in the extrusion cooking step slightly improved the rehydration in the boiled water of freeze dried sweet potato Dangmyun.

• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.593-600
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• 2014

Normal rice starch (NRS) possesses high gelling and retrogradation tendencies, with poor freeze-thaw stability. This study investigated the effects of partial replacement of waxy rice starch (WRS) with gums on the pasting and viscoelastic properties as well as the freeze-thaw stability of the WRS paste. Xanthan gum (XAT), locust bean gum (LBG), and their mixtures were individually mixed with WRS at a ratio of 1:19 (w/w). WRS-gum mixtures were pasted using a rapid visco-analyzer at 5% total solid content, and analyzed with respect to the pasting and viscoelastic characteristics, and freeze-thaw stability. Pasting properties of WRS were retarded in pasting temperature and enhanced in pasting viscosity (although peak viscosity was varied) by partial replacement with gum and gum mixtures. Storage moduli of WRS-XAT:LBG pastes became similar to those of NRS paste with increasing angular frequency from 1 to 10 rad/s. Finally, WRS-XAT and WRS-XAT:LBG possessed more enhanced freeze-thaw stability than NRS.