• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.1-8
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• 1993

Extruded defatted soy flour (DSF) with twin screw extruder was compared with steam treated DSF for soy sauce fermentation. Independent variables of response surface methodology (RSM) for extrusion were barrel temperature $(145{\sim}165^{\circ}C)$, feed moisture content $(25{\sim}35%)$, and feed rate $(20{\sim}30\;kg/hr)$. Extrusion conditions for production of the extrudates having highest water absorption capacity, lowest bulk density and highest expansion ratio were obtained by regression analysis of each dependent variable. Electron photomicrographs revealed significant increase of porosity inside the koji made from extruded DSF. Therefore, growth of fungi inside the koji made from extrudates of DSF was accelerated to achieve higher activities of protease, ${\alpha}-amylase$, and glucoamylase compared to the koji made from steamed DSF. Although amino acid composition of soy sauces prepared from two different DSF did not show any significant difference, the content of free amino acids in soluble nitrogen compounds was higher $(13%{\pm}2)$ in soy sauce made from extruded SDF. During the whole period of fermentation color of soy sauce made from extrudates of DSF was darker. Sensory evaluation did not reveal any serious off-odor and off-taste in the soy sauce fermented from extruded DSF.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.97-103
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• 1970

This experiment was carried out to investigate the yeasts for the brewing of soy sauce. The yeasts in the soy sauce koji were isolated and identified. And they were classified by coloring with the treatment of TTC(2, 3, 5 triphenyltetrazolium chloride) agar and counted. The result, obtained was as follows; a) The number of the yeasts in the Koji was increased in process of incubation time: about $97{\times}10^3$ per gram of Koji incubated for 3 days, $135{\times}10^3$ 4 days and $179{\times}10^3$ 5days. b) They were classified as 53.6-71.9 per cent of TTC while yeasts for the most, 5.6-11.1 per cent of red yeasts, 6.8-19.5 per cent of red pink yeasts and 11.1-22.6 per cent of pink yeasts. c) 30 strains of yeasts were isolated from the Koji optionally, and they were identified as 6 genera and 11 species: 5 strains of Saccharomyces rouxii, 2 strains of Saccharomyces fermentati, 1 strain of Saccharomyces rosei, 6 strains of Saccharomyces rosei, 6 strains of Hansenula anomala, 1 strain of Hansenula suaveolens, 6 strains of Pichia polymorpha, 2 strains of Debaryomyces hansenii, 2 strains of Debaryomyces nicotianae, 2 strains of Torulopsis candida 2 strains of Torulopsis sake and 1 strains of Torulopsis sake and 1 strain of Candida pelliculosa. d) The yeasts belonging to Hansenula suaveolens, Hansenula anomala Candida pelliculosa, Debaryomyces nicotianae and Pichia polymorplza were classified as TTC white yeasts, Saccharomyces rouxii and Sacharomyces rosei were red, Saccharomyces fermentati and Debaryomyces hancenii were red pink, and Torulopsis candida and Torulopsis sake were pink. e) Generally the growth of the yeasts isolated were rapid on the media containing none or 10 per cent of sodium chloride but almost restrained on the media containing 15-18 per cent of sodium chloride.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.239-245
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• 1992

Buci1llr.s 11c~h~n~1rnSiSi.As 3-2MI which is responsible for the special taste of traditionalKorean soy sause produced two kinds of proteinase. The activity of the proteinasc I washigher about two fold than that of proteinase 11. The optimai, reaction pH of proteinaseI and I1 wcre found to be 7-1 1.5 and 7-9. respectively. Proteinase I1 was more stable andactive than proteinase I at pH ranges around 3 to 5. The optimal te~tlperature of proteinaseI and I1 were 502. The temperature stabilitl of proteinase I1 was Inore stable thanproteinase 1 at temperature range around 30-quot;~A. ctivities of proteinase I and I1 graduallydeclined above $30^{\circ}$C and 45C. respectively. Proteinasc 1 was more active than proteinaseI1 at salt concentration range around 25-3500. The K,,, values of casein and soy proteinfor proteinase I were 6.89 mglml and 3.98 mglml. In case of proteinase 11. they were 9.00mgiml anti 11.44 111g/ml. respectively. The activity of the crudc enzyme was increased by1 rnM Pb(CH3COO). but was decreased by 5 n1M and 10 rnM of HgS04 and ZnS04. Thetwo proteinases produced amino acids and peptides from the soybean protein. The peptideswere digested into amino acids. Both protcinases were found to be the main enzymes thatproduced amino acids which make the main taste of traditional Korean soy sauce.al Korean soy sauce.