• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.817-822
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• 1998

The authors found out that Aspergillus oryzae ATCC 22787 has the activity to produce a pretty strong chitosanase. Therefore, the strain was used for preparing the chitosan hydrolysate with high antimicrobial activity. The antimicrobial activity of the chitosan hydrolysate was increased gradually with decreasing of viscosity of the solution. The chitosan hydrolysate showing viscosity $5{\sim}10{\;}cp{\;}(30^{\circ}C)$ of 2% solution was revealed the most strong antimicrobial activity. The growth of the Bacillus sp. isolated from the fish meat paste was inhibited with the concentration of 50 ppm. The astringent taste of chitosan solution was reduced with decreasing of viscosity of the solution. The fish meat paste products containing 0.3% chitosan hydrolysate was extended its shelf life by 6 days stored at $15^{\circ}C$, 4 days at $20^{\circ}C$ and 2 days at $30^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.823-826
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• 1998

It has been reported that alginic acid hydrolysate retains antimicrobial activity but the enzyme which hydrolyze alginic acid is not developed for industrial use. The authors developed chemical method for hydrolyzing alginic acid. For preparing alginic acid hydrolysate, equal quantity of alginic acid and ascorbic acid were added to water. Then the solution was heated at $121^{\circ}C$ for $20{\sim}30{\;}minutes$. The 4% solution of alginic acid hydrolysate was revealed relative viscosity 1.05, pH 3.2 and opaque whitish-yellow color. By addition of this hydrolysate to nutrient broth with the concentration of 0.1%, the growth of Bacillus sp. isolated from fish meat paste products was inhibited. The fish meat paste products containing 0.3% alginic acid hydrolysate prepared were prolonged their shelf life by 1 day stored at $30^{\circ}C$, 2 days at $20^{\circ}C$ and 4 days at $15^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.117-121
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• 1996

In order to find the reason for souring of Hansan sogokju (Korean traditional rice wine), microbial distribution, pH change and organic acids were analysed. Besides 161 mM of lactic acid as a major organic acid, small amount of acetic acid, malic acid, propionic acid were found in sogokju. Four different microbial strains were identified from the sogokju. These are two strains of Lactobacillus spp., Bacillus sp. and yeast. The pH of sogokju was changed from 4.01 to 3.29 during 18 days storage at $30^{\circ}C$. Amount of total acidity increased from 9 to 34.86 at the same condition. Notable change in the soured sogokju was an increase of the lactic acid (from 161 mM to 192 mM). So, we could assume that it was soured by an additional production of lactic acid by lactic acid bacteria during storage. The shelf life of sogokju was 41 days below $15^{\circ}C$ degree because this temperature was hard condition for the growth of Lactobacillus spp., causative bacteria responsible for additional lactic acid production.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1036-1042
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• 2002

During storage at $25^{\circ}C$, the effect of gas absorbents, such as carbon dioxide scavenger, ethylene absorber, and their combinations, on respiration characteristics and quality attributes of mature-green Mume fruits packaged in $30\;{\mu}m$ low density polyethylene (LDPE) film was examined. Changes in quality attributes of the fruits were observed in terms of weight loss, titratable acidity, pH, fish firmness, color, water-soluble solid, and chlorophyll contents. In the presence of ethylene absorber $(KMnO_4)$, the physiological injury was remarkably suppressed, and there was no significant injury in Mume fruits at $25^{\circ}C$ for 10 days. Yellowing and softening were also noticeably reduced by the combination of plastic film packaging and inclusion of ethylene absorber. The respiration rate was slower in fruits sealed with ethylene absorber than in those with absorbent-free packaging. Using ethylene absorber, levels of oxygen and carbon dioxide were maintained at 2-3 and 7-8%, respectively, during storage at $25^{\circ}C$ for 10 days. The addition of carbon dioxide scavenger $(Ca(OH)_2)$, negatively affected the quality attributes and respiration characteristics of the fruits. Overall results showed that ethylene removal by gas absorbent in the film packages significantly prolonged the shelf life of the fruits at ambient temperature.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.387-395
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• 2000

The rheological properties of wheat flour dough and qualities of bread prepared with 0, 10, and 20% of dietary fiber slurry extracted and purified from ascidian (Halocynthia roretzi) tunic were investigated. Water absorption of the dough increased with the increase of dietary fiber slurry. Both arrival and development time of the dough with 10 and 20% dietary fiber slurry added were shorter than those of the control. An increase in the added amount of the dietary fiber slurry resulted in an increase of weakness. The dough's extensibility and resistance to extension were decreased, and the ratio of resistance to extensibility (R/E) decreased with the increase in the dietary fiber slurry. The maximum viscosity gradually decreased with the increase in the amount of dietary fiber slurry, while the temperature of gelatinization was not changed. Both loaf and specific volume of bread were slightly decreased with an increase in the amount of dietary fiber slurry. Overall preference scores by sensory evaluation and the quality characteristics of the bread with up to 20% dietary fiber slurry added was not significantly different from those of the control(p<0.05). The results indicated that the addition of the dietary fiber from ascidian tunic retarded staling and improved the shelf-life of the bread by enhancing the water holding capacity.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.1113-1118
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• 2017

The objective of this study was to investigate the non-thermal sterilization effect of methods such as high hydrostatic pressure (HHP) and UV-irradiation (specifically with regard to the storage stability and shelf-life of carrot juice. The microbial counts of the non-sterilized product increased from 5.51 to 7.34 log CFU/mL up to the fifth day, and then decreased to 5.46 log CFU/mL at six days. UV-irradiation was increased from 2.37 to 4.92 log CFU/mL. HHP was maintained under the 3 log CFU/mL. The pH of UV-irradiation and HHP was maintained withing the range of 6.29~6.30 and 6.20~6.22 during storage. However, the pH arising from non-sterilization decreased from 6.31 to 4.49. The color of non-sterilization changed significantly during storage, but UV-irradiation and HHP were similar during storage. The ${\beta}$-carotene content of non-sterilization was noted to have decreased from 269.45 to $65.19{\mu}g/mL$ during storage. The UV-irradiation and HHP decreased from 263.46 and $268.35{\sim}281.16{\mu}g/mL$ to 243.42 and $244.09{\sim}269.29{\mu}g/mL$, respectively. In conclusion, these findings suggest that HHP can be used for the pasteurization, or sterilization, of carrot juice and the optimal condition is two minutes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.955-959
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• 2006

Effects of chlorine dioxide ($ClO_2$) on weight loss, polyphenol oxidase activity, and microbial change of fresh mushrooms (Agricus bisporus Sing) were investigated. Mushrooms were treated with 5, 10, and 50 ppm of $ClO_2$ solution. Mushrooms were stored at room temperature and $4^{\circ}C$. Weight loss for $ClO_2$ treated mushrooms was smaller than that of the control group. Polyphenol oxidase activity of the $ClO_2-treated$ samples stored at room temperature increased until day 2 of storage and then decreased, and the activity of the samples stored bacteria, yeast and mold counts than the control during storage. Aerobic bacterial counts for 50 ppm of $ClO_2$ treatment at $4^{\circ}C$ increased from $1.62{\times}10^2\;CFU/g\;to\;1.66{\times}10^7\;CFU/g$ at day 10 of storage, while control groups were from $1.00{\times}10^3\;CFU/g\;to\;3.72{\times}10^8\;CFU/g$. These results indicate that $ClO_2$ treatment could be useful in improving the quality and microbial safety of mushrooms.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.912-918
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• 2006

This study examined the improvement of bread quality with Curcula longa and Glycyorrhiza uralensis extract (CGE). When counted, the viable cell number in bread with 5% of CGE dramatically was decreased by about 1 log cycle as compared to that of bread without CGE. With regard to oxidation, the content of malonaldehyde diminished in breads with increasing amounts of CGE. Breads with 1 and 5% of CGE were shown to have the highest antioxidative effect. The moisture contents of bread with CGE and bread without CGE were not much different during the early storage period. After six days of storage, however, the moisture contents of bread without CGE and bread with 0.5% of CGE decreased about 16%. On the other hand, the moisture contents of bread with 1% and 5% of CGE did not change dramatically. Their moisture content was decreased by only 4% during the same storage period. Although color, lightness and redness gradually diminished with increasing amounts of CGE in bread, conversely yellowness increased. In the sensory evaluation, bread with 0.5% and 1% of CGE scored the highest: 3.66 and 3.67 out of 5, respectively. Bread with 5% of CGE scored the lowest of the various bread tested. From these results, the addition of 1% CGE in bread had a good effect on improvement of preservation and development of quality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.2
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• pp.139-147
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• 1991

The preservative effect of cellophane film packing on the quality of semi-salted and dried mackerel was studied. The product(P) of semi-salted and dried mackerel was prepared from raw mackerel by filleting, cleaning, soaking in 15%9v/w) salt solution for 30min, draining, packing with cellophane film (PT# 300, thickness:$20{\mu}{\textrm}{m}$) and drying for 4 hrs at $40^{\circ}C$ in hot air dryer. The product (C) was also prepared without cellophane film packing after draining. The product (C) and (P) were stored at $5.0{\pm}0.5^{\circ}C$. After processing and during storage, moisture content of product (P) was higher than that of product (C), but contents of VBN(volatile basic nitrogen), amino nitrogen and TMA of product (P) on dry basis were lower than those of product (C). Viable cell count, TBA value, peroxide value and decreasing rate of polyenoic acid of product (P) were also lower than those of product (C). In sensory evaluation, the shelf life of product (C) was about 9 days and that of product (P) was about 14 days. From the results of chemical and sensory evaluation, it was concluded that cellophane film packing was a good condition for preserving the quality of semi-salted and dried mackerel.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.874-881
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• 2015

In the food industry, thermal treatment is an important process for extending shelf-life of foods. However, heating process affects the physicochemical, nutritional, and microbial properties of foodstuff such as color, texture, pH, and proximate compositions. This study was conducted to select an optimal thermal treatment by observing physicochemical, nutritional, and microbial effects of shiitake mushrooms with different thermal treatment methods. Shiitake mushrooms were washed and sliced equally ($5cm{\times}0.5cm{\times}0.5cm$) and then heat-treated by three methods. Samples were heated in $100^{\circ}C$ boiling water, steamed for 10 min, or pan fried at $130^{\circ}C$ for 4 min. Total color difference values showed significantly increasing tendency with treatment time. For pH values, boiling water-treated mushrooms showed increasing tendency according to increased thermal treatment. For the results of hardness, boiling water or pan frying-treated mushrooms showed reduced tendency within 1 min. In the case of steam-treated mushrooms, hardness values were maintained for 1 min. Organic acid contents of steam-treated sample showed the lowest value among treatments. For microbial counts, steam-treated samples for 3 min showed the lowest value. Consequently, the results of this study suggest that steam treatment could be the optimal thermal treatment to minimize quality loss of shiitake mushrooms.