• Applied Biological Chemistry
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• v.13 no.1
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• pp.35-42
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• 1970

Five samples of Korean native Maeju(fermented soy-bean mash) loaves which were collected each from Kyunggi, Chungchung, Kangwon, Cholla and Kyungsang-Do were examined for their fermenting microorganisms. The results of taxonomic and ecological studies of fermentation microorganisms in these Maeju loaves were as the fellows. (1) The fungus flora grew only is the outer layer of Maeju loaves. Miscellaneous molds, 3 species of Mucor, 2 species of Pericallium., one species each of Scopulariopsis and Aspergillus, were isolated. None of them seemed exclusively predominant to be able to designate as the ecologically significant. (2) The bacterial flora which consisted of two species, Bacillus subtilis and Bacillus pumilus were distributed uniformly in th a entire Maeju loaves. The inner parts of Maeju loaves were especially inhabited solely by these bacterial flora. Probably the Korean native Maeju fermentation could be characterized by these bacterial flora. A Staphylococcus species was also isolated probably as a casual contaminant. (3) The yeasts, Rhodotorula flava and Torulopsis dattila, were isolated from Maeju loaves though their ecological significance was not clear. (4) The ecological aspects of fermentation microbes in the outer and inner parts of Maeju loaves were apparently different, consequently different fermentation processes might have occurred in these two parts and it brought quite different final outlooks in the final matured Maeju loaves. The outer part, rather rigid and dry, retained the light brown color of boiled soy-bean; whereas the inner part, soft and sticky, showed dark brown color indicating severe chemical changes. (5) The aflatoxin producing mold, Aspergillus oryzae was isolated from one sample among 5 of Maeju loaves. In addition to the low probability of isolability from Maeju loaves samples, since this mold grew only in the outer layer of Maeju loaves with such a low population density, about $10^4/g$, perhaps the aflatoxin problem in Korean native soysauce may not be critical.

• Applied Biological Chemistry
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• v.14 no.2
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• pp.137-148
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• 1971

Studies were carried out to investigate the main fermentation microorganisms and their flora changes during Korean native soy-sauce fermentation. Korean native Maeju loaves collected from 5 Do's were separated into surface and inner parts. Four different soy-sauces-the surface part Maeju fermented soy-sauce, the inner part, the surface and inner part combined Maeju fermented soy-sauce, and the semi-Japanese type soy-sauce were fermented and the changes of fermentation microorganism flora and the various chemical components during the period of their fermentations were studied. Besides, 14 home-made soy-sauces collected from 14 different places all over Korea were examined in comparison with the laboratory soy-sauces and to determine the characteristics of Korean native soy-sauce. The results were as follows: 1. The main microorganisms in Korean native soy-sauce fermentation were determined as; Aerobic bacteria: Bacillus subtilis, Bacillus pumilus Lactic acid bacteria: Pediococcus halophilus, Leuconostoc mesenteroides Yeasts: Torulopsis datila, Saccharomyces rouxii 2. Microflora changes during Korean native soy-sauce fermentation were as follows; Aerobic bacteria increased until the 2nd week of fermentation and then gradually decreased. The lactic acid bacteria increased until the 3rd week, after which decreased. When the lactic acid fermentation lowered the pH value to below the 5.4, yeasts were able to grow and participate the fermentation. As the production of organic acids amounted, to a certain height, the growth of all microorganisms lead to the period of decline or death at about the 2nd month of fermentation. After boiling of soy-sauce most microorganisms except a few of Bacillus sp. disappeared. Occosionally yeasts and lactic acid bacteria survived depending upon the composition of soy-sauce. 3. Changes of general chemical components influencing the microflora were investigated for the period of Korean native soy-sauce fermentation. Tetal acidity, salt concentration and total nitrogen were increasing steadily over the entire period of fermentation. pH values were dropping to a certain degree of about 4.5. Salt concentration and pH value seemed to be the important factors influencing the microflora. 4. The microflora were influenced by chemical components of soy-sauce. Aerobic bacteria were able to survive in all soy-sauce as they made spores. Growth of lactic acid bacteria was inhited at 23-26% of salt concentration and pH 4.8. Soy-sauce yeasts started to grow only at pH below 5.4 and seemed to be inhibited at around 26% of salt concentration under pH 4.5-4.7. 5. The open kettle boiling of soy-sauce, the characteristic process of Korean native soy-sauce manufacturing, was effective to sterilize microorganisms, increase the salt concentration, and coagulate proteins. 6. The average viable cell counts of microorganism found in collected samples of home-made Korean native soy-sauces were; Aerobic bacteria: $53{\times}10^2\;cell/ml$ Lactic acid bacteria: 34 cell/ml Yeasts: 14 cell/ml The average values of chemical compositions of samples of home-made Korean native soy-sauce were; Salt concentration: 28.9% pH value: 4.79 Total acidity(lactic acid): 0.91g/100ml Total nitrogen: 1.09g/100ml

• The Korean Journal of Mycology
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• v.19 no.2
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• pp.136-142
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• 1991

Colonial morphology of the various yeasts grown on the yeast morphology agar me­dium containing orange-yellow pigments extracted from the fruits of Gardenia jasminoides (GJPM) was investigated in hopes of the differential identification of yeasts on primary cultures. Colonies of Candida lusitaniae and Ca. guilliermondii on GJPM turned to prussian blue within three days of incubation and Ca. tropicalis and Ca. viswanathii turned to bluish gray but the latter species turned to deep blue after 7 days. Ca. krusei, Saccharomyces cerevisiae, and Torulopsis glabrata showed neutral gray, grayish green, and baby blue respectively after one or two weeks. However, the colonies of Ca. albicans and parapsilosis remained unchanged even after 20 days. Colonial color of Cryptococ­cus neoformans showing brown to purple brown was distinguishable not only from buff color of Cr. laurentii after one or two weeks incubation but also from those of Candida spp. Growth of certain species was promoted on GJPM. The findings clearly showed that Ga. jasminoides pigments medium was useful to the morphological differentiation of medically important yeasts which were often encountered in sputum or other clinical specimens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.471-476
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• 1998

Microbiological spoilage of marine fish is complex process occurring by bacteria, yeasts and molds. There have been rare study for saprophytic yeasts although having enormous numbers of bacteriological studies on the spoilage of marine fish. The 14 genera of yeasts isolated from mackerel (Scomber japonicus) with high frequency of occurrence were Candida sp., Rhodotorula sp., Torulopsis sp., Cryptotoccus sp. and Tricosporon sp. Among these ones Candida lipolytica was identified as the strongest proteolytic yeast, then named Candida lipolytica FM5 (C. lipolytica FM5). C. lipolytica FM5 showed optimum growth at $25^{\circ}C$, pH 7.0 and could grow at $5^{\circ}C$ and in medium containing $10\%$ sodium chloride, To evaluate the saprophytic activity of the selected strain, C, lipolytica FM5 and Pseudomonas fluorescens ATCC 17571 which is one of representative spoilage bacteria were individually inoculated into the sterilized fish muscle homogenates, and then pH changes and volatile basic nitrogen (VBN) values were checked during the storage at various temperatures. According to the experimental results, the productions of VBN by C. lipolytica FM5 in the fish muscle homogenates were 50 mg-N/100 g at $5^{\circ}C$, 152 mg-N/100 g at $15^{\circ}C$ and 379 mg-N/100 g at $25^{\circ}C$ for 1 week storage, respectively. Above results were nearly same as in case of Ps. fluorescens ATCC 17571 inoculation. It suggest that sapyophytic yeasts also have important role in spoilage of marine fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.79-110
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• 1976

In Korea fermented fish and shellfish have traditionally been favored and consumed as seasonings or further processed for fish sauce. Three major items in production quantity among more than thirty kinds which are presently available in the market are fermented anchovy, oyster and small shrimp. They are usually used as a seasoning mixture of Kimchi in order to provide a distinctive flavor. Fermented small shrimp, Acetes chinensis is most widely and largely used ana occupies an important position in food industry of this country. But no study on its taste compounds has been reported. This study was attempted to establish the basic data for evaluating taste compounds of fermented small shrimp. The changes of such compounds during fermentation as free amino acids, nucleotides and their related compounds, TMAO, TMA, and betaine were analysed. In addition, change in microflora during the fermentation under the halophilic circumstance was also investigated. The samples were prepared with three different salt contents of 20, 30 and $40\%$ to obtain the proper degree of fermentation at a controlled tempeature of $20{\pm}2^{\circ}C$. The results are summarized as follows: Volatile basic nitrogen increased rapidly until 108 days of fermentation and afterwards it tended to increase slowly. Amino nitrogen also increased rapidly until 43 days of fermentation and then increased slowly. Extract nitrogen increased and marked the maximum value at 72 day fermentation and then decreased slowly. ADP, AMP and IMP tended to degrade rapidly while hypoxanthine increased remarkably at 27 day fermentation but slightly decreased at 72 day fermentation. It is presumed that the characteristic flavor of fermented small shrimp might be attributed to the relatively higher content of hypoxanthine. In the free amino acid composition of fresh small shrimp abundant amino acids were proline, arginine, alanine, glycine, lysine, glutamic acid, leucine, valine and threonine in order. Such amino acids like serine, methionine, isoleucine, phenylalanine, aspartic acid, tyrosine and histidine were poor. In small shrimp extract, proline, arginine, alanine, glycine, lysine and glutamic acid were dominant holding $18.5\%,\;14.6\%,\;10.8\%,\;8.7\%,\;8.1\%\;and\;7.7\%$ of total free amino acids respectively. The total free amino acid nitrogen in fresh small shrimp was $63.9\%$ of its extract nitrogen. The change of free amino acid composition in the extract of small shrimp during fermentation was not observed. Lysine, alanine glutamic acid, proline, glycine and leucine were abundant in both fresh sample and fermented products. The increase of total free amino acids during 72 day fermentation reached approximately more than 2 times as compared with that of fresh sample and then decreased slowly. Fermented small shrimp with $40\%$ of salt was too salty to be commercial quality as the results of organoleptic test showed. It is found that 72 day fermentation with $20\%\;and\;30\%$ of salt gave the most favorable flavor. It is convinced that the characteristic flavor of fermented small shrimp was also attributed to such amino acids as lysine, proline, alanine, glycine and serine known as sweet compounds, as glutamic acid with meaty taste, and as leucine known as bitter taste. The amount of betaine increased during fermentation and reached the maximum at 72 day fermentation and then decreased slowly TMA increased while TMAO decreased during fermentation. The amount of TMAO nitrogen in fermented small shrimp was $200mg\%$ on moisture and salt free base. Betaine and TMAO known as sweet compounds were abundant in fermented small shrimp. It is supposed that these compounds could also play a role as important taste compounds of fermented small shrimp. At the initial stage of fermentation, Achromobacter, Pseudomonas, Micrococcus denitrificans which belong to marine bacteria were isolated. After 40 day fermentation, they disappeared rapidly while Halabacterium, Pediococcus, Sarcian, Micrococcus morrhuae and the yeasts such as Saccharomyces sp. and Torulopsis sp. dominated. It is concluded that the most important taste compounds of fermented small shrimp were amino acids such as lysine, proline, alanine, glycine, serine, glutamic acid, and leucine, betaine, TMAO and hypoxanthine.