• Korean Journal of Food Science and Technology
• /
• v.35 no.6
• /
• pp.1174-1181
• /
• 2003

A part of Aspergillus oryzae koji was replaced with Bacillus sp. koji to improve the quality of kochujang, and the resulting effects on enzyme activities, microbial characteristics, and physicochemical properties were investigated during fermentation. The activity of amylase was higher in the kochujang prepared with Asp. oryzae koji. The activity of protease increased as the ratio of Bacillus. sp. koji increased. Viable cell counts of yeast and bacteria of the kochujang increased with increasing ratio of Bacillus sp. koji. The Hunter a-values of the Bacillus sp. koji kochujang were higher, and the degree of increase in the total color difference $({\Delta}\;E)$ was lower in the Bacillus sp. koji group. Consistency and water activity of the kochujang prepared with Bacillus sp. koji was higher, and the pH and titratable acidity of the kochujang also changed slightly. As the ratio of Asp. oryzae koji increased, sugar content decreased. However, the ethanol content of the kochujang did not significantly change. Amino nitrogen content of the kochujang increased, while ammonia nitrogen content decreased as the ratio of Bacillus sp. koji increased. After 12 weeks of fermentation, the result of sensory evaluation showed that C kochujang (75% of Asp. oryzae koji replaced by Bacillus sp.) was more acceptable (p<0.05) than the other groups in taste, color, flavor, and overall acceptability.

• Korean Journal of Food Science and Technology
• /
• v.35 no.6
• /
• pp.1237-1243
• /
• 2003

As a newly emerging pasteurization method for improving the shelf-life of powdered ginseng, the corona discharge generated at high voltage conditions was examined for its effects on microbial pasteurization, physicochemical characterization, and sensory evaluation. The pasteurizing effects of corona discharge on total bacteria, yeast, molds, and coliforms increased with increasing voltage. However, corona discharge treatment of 5 kv/cm did not show significant effects of pasteurization on the yeast, molds, and coliforms. Treatment with 20 kv/cm reduced about 95% of the total bacteria $(6.14{\pm}0.04{\rightarrow}\;4.59{\pm}0.04$) and coliforms ($2.43{\pm}0.05{\rightarrow}\;1.00{\pm}0.05$) and 99% of the yeast and molds ($4.65{\pm}0.06{\rightarrow}\;2.73{\pm}0.06$). The proximate analysis, minerals, free sugars, crude saponin, and colors of the control ginseng and the ginseng treated with 20 kv/cm were not significantly different at p<0.05. Corona discharge of up to 20 kv/cm did not affect the proximate analysis, minerals, free sugars, crude saponin, and colors of the powdered ginseng. Sensory evaluation scores on color, flavor, taste and overall acceptability between the control ginseng and ginseng treated with 20 kv/cm corona discharge were not significantly different at p<0.05 level. Consequently, corona discharge treatment is thought to be a good alternative pasteurization method for improving the shelf-life of powdered ginseng due to its effective pasteurization, maintenance of nutrients and good sensory characteristics.

• Journal of Food Hygiene and Safety
• /
• v.5 no.1
• /
• pp.13-19
• /
• 1990

The microbial populations of exportable ginseng leaf tea were $3.6{\times}10^{5}/g$ in mesophilic aerobic bacteria, $2.1{\times}10^{3}/g$ in mesophilic aerobic spores, $1.6{\times}10^{4}/g$ in yeast, $1.9{\times}10^{4}/g$ in molds and $1.2{\times}10^{4}/g$ in coliforms, respectively, which are higher levels than the legaJIy permissible loads of microorganisms for ginseng powders in Korea. In a comparative study of the decontaminating effects on microorganisms, ethylene oxide fumigation and 5 kGy irradiation could decrease microorganisms below the detectable level. And there is no growth of microorgllnisms after three months of storage at $30{\pm}1^{circ}C$. The decimal reduction doses (Dw value) for microorganisms contaminated were 0.70 kGy in coliforms, 0.75 kGy in total bacteria, 0.85 kGy in molds. and 0.95 kGy in yeast, respectively. In the organoleptic test for ginseng leaf tea, the irradiated samples showed no significant difference from the control group in overall flavor, taste, color and acceptability. However the extracts of ethylene oxide fumigated sample were significantly different in color and taste from other groups even after three months storage.

• Korean Journal of Food Science and Technology
• /
• v.33 no.3
• /
• pp.327-332
• /
• 2001

Attempts were made to investigate the effect of gamma irradiation and heat treatment on quality changes of Bulgogi sauce during the storage at 4 and $20^{\circ}C$. Total acidity, Surface color, brix, microbial growth and sensory quality of test products were evaluated during storage. Total acidity of sauce did not change during storage at $4^{\circ}C$, whereas those of control and 4 kGy groups changed significantly during storage at $20^{\circ}C$. Gamma irradiation and heat treatment had little effect on brix of the suace during storage period. Surface color of control and 4 kGy group significantly changed during storage, especially at $20^{\circ}C$. Sucrose contents in sauce decreased during storage, while glucose and fructose contents increased. Sensory quality of sauces stored at $4^{\circ}C$ for 12 weeks was similar, except the control. Control and 4 kGy treated sauces stored at $20^{\circ}C$ for 6 week had detectable levels of off-flavor. Colifrom bacteria were not detected in sauces treated by either heat or gammma-ray. Total acrobic increases in colony counts were slower at $4^{\circ}C$. Yeasts or molds were not detected in sauces treated by heat or gamma-ray over 7-10 kGy. These results indicated that gamma irradiation over 7kGy or heat treatment of the sauce maintained acceptable quality.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.31 no.2
• /
• pp.204-210
• /
• 2002

The quality characteristics and sensory evaluation of chungkookjang were investigated. The samples were prepared and fermented by the inoculation of Bacillus strains; B. subtilis, B. natto and B. licheniformis as a single starter, and mixed culture of B. natto and B. licheniformis on the industrialized model system. It was shown that microbial growth, protease activity, contents of amino-and ammonia-nitrogen and contents of organic acid were higher in B. subtilis inoculated sample, and were lower in B. licheniformis inoculated one. General quality characteristics of sample inoculated by mixed culture of B. natto and B. licheniformis took a middle position between each B. natto and B. licheniformis inoculated one. Fifty eight species of odor components were identified. Ethanol, 3-methyl-1-butanol, acetic acid, benzaldehyde and alkyl pyrazines were identified in all samples and most of other flavor components were strain specific. The contents of unpleasant smell components, alkyl pyrazines and benzaldehyde, were lower in B. licheniformis inoculated sample. The sensory evaluations showed that chungkookjang manufactured from mixed culture of B. natto and B.licheniformis was most acceptable. Therefore, results indicated that chungkookjang manufactured from mixed culture of B. natto and B. licheniformis induced better sensory quality than that of the control.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.8
• /
• pp.1064-1069
• /
• 2006

This study was conducted to sanitize commercial powdery soup by gamma irradiation. Total aerobic bacteria counts were $3.22{\sim}3.77\;log\;CFU/g$ in non-irradiated samples, which decreased with irradiation dose and were not detected in irradiated samples at 3 kGy or more $(<10^2\;CFU/g)$ during accelerated storage $(60^{\circ}C,\;2\;weeks)$. Microbial counts did not significantly increase in all samples during accelerated storage period. Yeasts, molds, and coliform bacteria were not detected in all samples. Irradiated samples showed undesirable changes in flavor, taste, and overall acceptability and acceptance decreased in all samples after 2 weeks at $60^{\circ}C$. These results suggested that gamma irradiation at 3 kGy was effective to ensure the microbiological quality of commercial powdery soup with minimized sensorial changes, but further studies should be investigated to reduce detrimental effects induced by irradiation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.2
• /
• pp.151-156
• /
• 1985

In order to develop a sanitary and economic storage method for chicken carcass by gamma-irradiation, the samples irradiated with 5 to 10 kGy were stored at 3 to $4^{\circ}C$ for 41 days, and the changes in ordour, appearance and the cooking guality of stored samples were determined. The nonirradiated samples which stored for more than 7 days were not tested because of microbial spoilage on the chicken carcasses. However, the quality of irradiated groups of 5 to 10 kGy was similar to that of fresh chicken for about 15 days though it deteriorated slightly after 20 days, however, they were still acceptable to eat each after 27 days of storage. The overall acceptability, flavor and texture was not significantly different in the samples of nonirradiated those of irradiated immediately and those of irradiated and then stored for 15 days when they were prepared for Sam Gei Tang arid steamed chicken. The acceptibility of Sam Gei Tang prepared with chickens after 15 days of the storage, the irradiated groups of 8 and 10 kGy showed a similarity to the chickens prepared immediately after slaughter. In steamed chickens prepared with the samples stored for 15 days texture of the irradiated group was superior to that of the nonirradiated fresh chicken, and there were no statistical differences in the flavors between each group.

• Food Science and Preservation
• /
• v.20 no.1
• /
• pp.7-13
• /
• 2013

Mushrooms have a shorter shelf-life than most vegetables because of their very high respiration rates, sensitivity to enzymatic browning and susceptibility to microbial spoilage. This study was conducted to investigate effects of various packaging materials and precooling on the quality of mushrooms (Agaricus bisporus). Mushrooms were precooled at $4^{\circ}C$ for three hours and packaged using the following packaging materials; 1) polyethylene (PE) film bags of 0.03 mm thickness, 2) polypropylene (PP) film bags of 0.03 mm thickness, and 3) polystyrene (PS) tray+polyvinyl chloride (PVC) wrapper. The physiological changes (weight loss, gas composition, color, firmness, and sensory evaluation) associated with postharvest deterioration were monitored for 17 days at $10^{\circ}C$. The results showed that the PP film bag maintained quality of mushrooms most effectively, especially PP film bags inhibited decreasing firmness. The samples also exhibited smaller decreases in weight loss rate (0.57%) and Hunter L value (84.44) than PS tray+PVC wrapper (7.73%, 82.19) and PE film bags (0.89%, 82.96). Sensory evaluation level in all samples remained relatively constant during the first 5 days of storage. However, PE film bags and PS tray+PVC wrapper showed lower score of flavor, texture and color than PP film bags after 8 days of storage. This study suggested that PP film bag packaging effectively extends shelf-life of mushrooms during storage.

• Journal of Animal Science and Technology
• /
• v.46 no.5
• /
• pp.871-878
• /
• 2004

Pulsed electric fields(PEF) technology is one of the latest nonthermal methods of food processing for obtaining safe and minimally processed foods. This technology can be effectively explored for obtaining safe food with minimum effect on nutritional, flavor, rheological and sensory qualities of food products. The process involves the application of high voltage(typically 20 ${\sim}$ 80 kv/cm) to foods placed between two electrodes. The mode of inactivation of microorganism; by PEP processing has been postulated in term; of electric breakdown and electroporation. The extent of destruction of microorganisms in PEF processing depends mainly on the electric field strength of the pulses and treatment time. For each cell types, a specific critical electric field strength and specific critical treatment time are required depending on the cell characteristics and the type and strength of the medium where they have been present. The effect also depends on the types of microorganisms and their phase of growth. A careful combination of processing parameters has to be selected for effective processing. The potential applications of PEF technology are numerous ranging from biotechnology to food preservation. With respect to food processing, it has already been established that, the technology is non-thermal in nature, economical and energy efficient, besides providing minimally processed foods. This article gives a brief overview of this technology for food processing applications.

• Korean Journal of Food Science and Technology
• /
• v.32 no.6
• /
• pp.1258-1265
• /
• 2000

In oder to acquire microbial agents that can be utilized for control of aflatoxin produced by Aspergillus. flavus and Asp. parasiticus, antifungal bacteria were isolated. Antifungal bacteria was identified as Bacillus spp. based on morphology and physico-biochemical characteristics. Amount of aflatoxin $B_1$ from Doenjang(soybean paste) prepared with Asp. flavus, Asp. parasiticus, antifungal bacteria(Bacillus sp.), or mixture of Asp. flavus and Asp. parasiticus was 27.2 ppb, 30.3 ppb, 3.4 ppb, and 3.7 ppb, respectively. Aflatoxin $B_1$ was not detected from Doenjang(control) and Doenjang prepared with antifungal bacteria. Content and compositions of free sugars, fatty acid, organic acid and free amino acid in Doenjang prepared with Asp. flavus and Asp. parasiticus, antifungal bacteria and mixture of Asp. flavus and Asp. parasiticus were not significantly different. For volatile flavor compounds of Doenjang prepared with antifungal bacteria, 2-pentyl furan and butanoic acid were disappeared or reduced, while octadecene compounds were produced. However, those of Doenjang prepared with Asp. flavus or Asp. parasiticus and Doenjang(control) were not significantly different. These results suggested that the antifungal bacteria(Bacillus sp.) inhibited production of aflatoxin and that antifungal bacteria did not effect the quality of Doenjang.