• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.165-172
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• 2014

Mixed fermentation of cow milk was performed by sequential co-cultures with Bacillus subtilis and Lactococcus lactis. After a first fermentation step with B. subtilis for 6 h, the number of viable cells increased to $2.5{\times}10^8$ CFU/mL. The second fermentation step with L. lactis resulted in increased viable cells $1.09{\times}10^{10}$ CFU/mL for 3 days and increased acidity. However, the number of viable B. subtilis cells was decreased greatly to $5{\times}10^1$ CFU/mL following fermentation with L. lactis. Milk proteins were markedly hydrolyzed by the first fermentation after 2 h, and the second fermentation induced curd formation in milk. However, after 4 h, the first fermentation resulted in higher whey separation and 80 mg% tyrosine content. Gamma-aminobutyric acid (GABA) production was dependent upon the degree of protein hydrolysis by first fermentation. Second fermentation resulted in 0.14% GABA. The milk fermented by B. subtilis indicated the rough surface of yogurt depended upon the degree of protein hydrolysis. In conclusion, set-type yogurt was efficiently produced by co-culturing of milk, and fortifying with peptides, GABA, and probiotics.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1518-1522
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• 1999

This work was to determine the quality changes of milk with respect to the chemical components when HTST pasteurized by microwave energy. Raw milk was HTST pasteurized $(at\;72^{\circ}C\;for\;15\;sec)$ by three methods; by heating in a stainless steel tube immersed in a hot water bath (MP0), by heating in a microwave cavity to a desired temperature and then holding in a hot water bath (MP1) and by both heating and holding in a microwave cavity (MP2). There were no significant differences in pH and titratable acidity before and after pasteurization and among the different pasteurization methods. MP1 or MP2 showed better retention or less destruction than MP0 with respect to vitamin A, vitamin $B_1$, ascorbic acid and lysine content. The higher retention of nutrients of the MP1 or MP2 supports the possibility of using microwave energy for the pasteurization of milk and other fluid food products.

• Journal of Applied Biological Chemistry
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• v.62 no.3
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• pp.299-304
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• 2019

Yogurt was prepared with different substitution ratio [10, 20, 30, and 50% (w/w)] of skim milk with enzymatically saccharified Korean rice wine lees powder (eKRWLP) and fermented with commercially available mixed lactic acid bacteria (Bifidobacterium longum, Lactobacillus acidophilus, Streptococcus thermophilus) at $40^{\circ}C$ for 18 h. Fermentation characteristics were evaluated in terms of acid production (pH and titratable acidity) and viable cell counts of lactic acid bacteria. The pH of yogurts decreased with increasing eKRWLP substitution ratio of skim milk. After 12 h fermentation, titratable acidities of eKRWLP substitution and control (yogurt made without eKRWLP) were 0.84~1.04% and 0.93%, respectively. The titratable acidities of yogurts prepared with 10 and 20% substitution ratio increased than that of the control yogurt, but titratable acidities of yogurts of 30 and 50% substitution ratio decreased. After 9 h fermentation, the number of viable lactic acid bacterial cell were increased to 8.18~8.24 log CFU/g in all yogurts. In sensory evaluation, there were similar preference for eKRWLP yogurts prepared with 10 and 20% substitution ratio and the control. When eKRWLP substitution and control yogurts fermented for 9 h were incubated at $4^{\circ}C$, their pHs and titratable acidities were slightly changed but the number of viable lactic acid bacteria were well maintained above $10^7CFU/g$ for 11 days in yogurts prepared with 10 and 20% substitution ratio among eKRWLP substitution yogurts. These results suggest that eKRWLP can be used as substituent of skim milk and the optimum substitution ratio is around 10~20%.

• Korean journal of food and cookery science
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• v.3 no.2
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• pp.75-80
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• 1987

For the manufacture of soybean cheese, curds were made from soy milk using either lactic starter or CaCl$_2$and ripened for 3 weeks. When papain was added during ripening, the amout of soluble protein increased. The yields of 3 soybean cheese were 76~88%, indicating that considerable loss of soy protein did not occur during the processing. During the period of ripening the change of moisture content was about 1 n. Total acidity of 3 soy cheese increased, demonstrating the production of lactic acid through lactic fermentation. Texture determined by Instron showed that 3 soy cheese had their own characteristic texture profile curve and that the cheese without papain treatment received the highest textural parameters. 3 manufactured soy cheese received 3-4 (good-very good) sensory scores in appearance, flavor and texture. General acceptibility of 3 cheese were evaluated as desirable or very desirable.

• YAKHAK HOEJI
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• v.32 no.6
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• pp.394-401
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• 1988

Lactobacillus casei was treated with N-methyl-N'-nitro-N-nitrosoguanidine(NTG) to obtain resistant mutants to rifampicin. Freshly grown cells of the strain suspended in tris-maleic acid buffer were exposed to NTG of $50{\mu}g/ml$ for 30min. Five colonies of the NTG-induced mutants showed distinct resistance to rifampicin. They also exhibited identical characteristics with the original Lactobacillus casei when they were tested for growth, titrable acidity and sugar fermentation. It is suggested that they can be utilized as efficieient starter cultures for fermented milk.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.542-546
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• 1999

Uncoated, ethyl cellulose(EC) coated or methacrylic acid copolymer(MAC) coated ferrous sulfate was added to the yoghurt made from whole milk powder and quality changes of those yoghurt were observed. Among treatments uncoated ferrous sulfate added yoghurt showed the lowest quality in the view of pH, total acidity, total counts of lactic acid bacteria, and sensory characteristics. Quality change of MAC comparing to control was lower than that of EC. MAC and EC showed higher TBA value than no iron added or uncoated iron added one during storage. From sensory evaluation, MAC was not signif icantly different from control in color and off flavor after one day storage(p>0.05), however significant difference was observed in off flavor after 7 day storage(p<0.05). From above results, MAC coated ferrous sulfate added yoghurt showed better quality than uncoated or EC coated ferrous sulfate added one during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.602-609
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• 2015

In this study, for modernization of Korean traditional fermented milk, Tarak was made using four kinds of commercial Makgeolli based on the ancient cookbook Suwoonjabbang. Samples of Tarak were periodically collected during 24 h of fermentation at $37^{\circ}C$. After fermentation, changes in pH, titration acidity, and viscosity were analyzed. Fermentation metabolites, including organic acids and free sugars, were analyzed by HPLC. Numbers of yeast and lactic acid bacteria during 24 h of fermentation were measured. The pH of Tarak significantly decreased (P<0.01), whereas its acidity significantly increased (P<0.01) during fermentation. The viscosity increased during 8~24 h of fermentation until curd was separated in Tarak. The level of ethanol increased from 0.37~0.52 mg/mL to 0.51~0.71 mg/mL during 24 h of fermentation. Lactic acid and lactose were the major organic acid and free sugar in Tarak, respectively. The number of lactic acid bacteria increased from 5.23~6.25 log CFU/mL to 9.87~10.41 log CFU/mL at the beginning during 24 h of fermentation. The number of yeast increased from 5.14~6.47 log CFU/mL to 6.99~7.73 at the beginning during 24 h of fermentation at $37^{\circ}C$. The major strains of Tarak were Pediococcus acidilactici, Lactobacillus fermentun, Lactobacillus curvatus, and Saccharomyces cerevisiae. Therefore, we concluded that Tarak was a fermented milk by both lactic acid bacteria and yeast, which was similar to koumiss or kefir.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.39-49
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• 1999

Curd yoghurts were manufactured by addition of chestnuts and walnuts which were special agricultural products in Chungnam area. The nut powders were added to the yoghurts in the given concentration of 1~4%. The yoghurts after 12 hours fermentation were examined for pH, acidity, cell counts of lactic acid bacteria, viscosity, chemical composition and sensory test and preservation of yoghurts. The results obtained were summarized as follows; 1. The chestnut powder decreased pH, whereas increased acidity in yoghurts, however, the walnut powder did not change significantly for pH and acidity in yoghurts. 2. The cell counts of lactic acid bacteria was higher for 2% chestnut powder yoghurt ($2.6{\times}10^9/ml$) than 2% walnut powder yoghurt ($1.7{\times}10^9/ml$) and control yoghurt. 3. The viscosity of yoghurt was higher for 4% chestnut powder yoghurt (3,225 centipoise) than control (1,638 centipoise) and 4% walnut powder yoghurt (2,010 centipoise). 4. The protein content of yoghurts were 3.99% for both 2% chestnut powder and 2% walnut powder yoghurts, and solid-non-fat contents of yoghurt were 15.10% for chestnut powder yoghurt and 13.65% walnut powder yoghurt. 5. The scores of sensory tests were higher in chestnut powder yoghurt for tastes, odor and texture, and in walnut powder yoghurt for tastes, odor and texture compared to control yoghurt. 6. When yoghurts were stored at $5^{\circ}C$ for 14 days for preservation test, the acidity and number of lactic acid bacteria were not changed significantly.

• Food Science and Preservation
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• v.24 no.8
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• pp.1067-1078
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• 2017

This study was carried out to investigate the physicochemical and antioxidant properties of fermented milk with addition of hot water extract of Cordyceps militaris grown upon Tenebrio molitor. The general components of Cordyceps militaris grown upon Tenebrio molitor are moisture 10.85%, crude protein 18.44%, crude fat 2.07%, crude ash 5.46%. The DPPH radical scavenging activities of different solvents were the highest (74.81 EDA%) with hot water extract sample. The acidity of fermented milk was high with increasing amount of extracts. The pH of fermented milk reached 4.60-4.66 after 4 h of fermentation, and the number of lactic acid bacteria was highest (11.70 log CFU/mL) with 1% fermented milk. The moisture content of fermented milk showed no significant difference. In addition, contents of crude protein were not significantly different according to addition amount. Regarding Hunter's color values, L value decreased as the amount of extract increased, whereas a value and b value increased. The content of free amino acid increased with increasing amount of extract. The DPPH free radical scavenging ability and ABTS free radical scavenging ability of fermented milk were significantly different as the addition amount of extract increased. In the sensory evaluation, fermented milk containing 1% of extract showed the highest preference.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.677-686
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• 2004

The objective of this experiment was to select the best strain of lactic acid bacteria for the manufacture of new type of yogurt with rice powders. Changes in pH, titratable acidity, viable cell counts, viscosity, organic acid contents, carbohydrates during fennentation were monitored and sensory evaluation were examined. The yogurt added with 4% rice or skim milk powders and L. salivarius ssp. salivarius culture did not reach pH 4.5, because the production of acids in this media for the culture was weak. The yogurt added with 4% rice or skim milk powder with L. casei, the pH was low and the titratable acidity was high, and therefore the quality of yogurt after 8 hours from fermentation was not high. The yogurt added with 4% rice or skim milk powders with a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was considered best for achieving pH 4.5 and titratable acidity of 1.0 % from 8 to 14 hours. The yogurt with a mixed culture had more acetic acid. Galactose was accumulated when L. salivarius ssp. salivarius or the mixed culture were used for fermenting yogurt. In sensory evaluation, the yogurt with the mixed culture received high overall sensory score. From these results, a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was identified as the best for the manufacture of yogurt added with rice powder.