• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.372-379
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• 2016

This study was performed to investigate the quality characteristics of various salted (8, 10, and 12%) Doenjang prepared with fermented Hwangchil (Dendropanax morbifera) extract as well as the effect of Bacillus methylotrophicus S8 strain, isolated from soy sauce, as a starter culture. After fermentation, the total cell number of low-salted Doenjang (8% and 10%) prepared with fermented Hwangchil was lower than that of Doenjang without fermented Hwangchil. Low-salted Doenjang (8% and 10%) showed higher total acidity, amino acid, and organic acid levels as well lower pH levels than high-salted Doenjang (12%), indicating active fermentation. The highest levels of lactic acid (48.1 mg/L) and glutamic acid (549.0 mg/L) were observed in low-salted Doenjang (8%) fermented with B. methylotrophicus S8 strain. The low-salted Doenjang (8%) fermented with B. methylotrophicus S8 also showed the highest score in overall preference of sensory evaluation. These results indicate that Hwangchil extract fermented with B. methylotrophicus S8 can be used as a starter for making low-salted Doenjang, resulting in improved palatability, and inhibition of abnormal fermentation.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.603-610
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• 2001

The quality characteristics of soy yogurt prepared with different proteolytic enzymes and starter culture were evaluated. In order to facilitate the growth of lactic acid bacteria and subsequent production of lactic acid, soy protein isolate(SPI) was hydrolyzed using three kinds of proteases; one extracted from Aspergillus oryzae, bromelain and ${\alpha}-chymotrypsin$. The cultural systems employed thereafter for lactic fermentations were: 1) Bifidobacterium bifidum, 2) B. bifidum and Lactobacillus acidophilus, 3) B. bifidum and Lactobacillus bulgaricus. In soy yogurt, pH was more decreased by mixed culture method than single culture method with the accumulation of lactic acid. Viable cells of lactic acid bacteria in soy yogurts were measured $10^8$ CFU/g by the single culture method while $10^9$ CFU/g by the mixed culture method except ${\alpha}-chymotrypsin$ treatment. The amount of free amino acids in soy yogurts were substaintially increased by enzyme treatment. Viscosity was decreased by enzyme treatment, resulting in higher viscosity by ${\alpha}-chymotrypsin$ treatment. Water holding capacity was found to be higher in the single culture method in case of enzyme treatment. Among the various volatile flavor components isolated and identified after enzyme hydrolysis, acetaldehyde, ethanol, diacetyl, butyl alcohol contents tended to increase by lactic fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1010-1016
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• 1999

Protease related mold was isolated and selected as a starter culture for commercial production of meju. Isolated microorganism was identified as Syncephalastrum racemosum PDA 132 2. To obtain basic data about protease for production of soybean peptides and application of the strain in meju fermentation, we extrated and purified protease and charateristics of the enzyme were investigated. The optimum condition for the production of enzyme was pH 4.0, 30oC, 5 days. The protease was purified 19.7 folds by gel filtration and ion exchange chromatography and specific activity was 12.4unit/mg. The purified enzyme was 34kDa in size, thiol protease(100% inhibited by PCMB), and was acidic protease(stable between pH 2.0~5.0). Vmax of the enzyme was 2.14 g/min which was lower(1/50) than that of by Asp. wentti and B. subtilis.

• Food Science of Animal Resources
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• v.24 no.3
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• pp.273-276
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• 2004

The objective of this study was to investigate the microstructure of folic acid-contained yogurt. Folic acids (25 and 50%) were added to milk preparation prior to pasteurization, then starter culture was added. The microstructure of yogurt containing folic acid was determined by the size of cluster of casein micelle using scanning electron microscopy and transmission electron microscopy. The cluster of casein micelle in yogurt containing folic acid were showed larger size than in control (p<0.05). In addition of 50% of folic acid, cluster of casein micelle per unit area was exhibited the highest number among tested yogurts. From these results, folic acid concentration of yogurt may be affected by mouth-feel of yogurt texture as well as the aggregation of casein micelle.

• Mycobiology
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• v.44 no.3
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• pp.155-161
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• 2016

The most economically important species used in a wide range of fermentation industries throughout Asia belong to Aspergillus section Flavi, which are morphologically and phylogenetically indistinguishable, with a few being toxigenic and therefore a major concern. They are frequently isolated from Korean fermentation starters, such as nuruk and meju. The growing popularity of traditional Korean alcoholic beverages has led to a demand for their quality enhancement, therefore requiring selection of efficient non-toxigenic strains to assist effective fermentation. This study was performed to classify the most efficient strains of Aspergillus section Flavi isolated from various types of traditional wheat nuruk, based on a polyphasic approach involving molecular and biochemical evaluation. A total of 69 strains were isolated based on colony morphology and identified as Aspergillus oryzae/flavus based on internal transcribed spacer and calmodulin gene sequencing. Interestingly, none were toxigenic based on PCR amplification of intergenic regions of the aflatoxin cluster genes norB-cypA and the absence of aflatoxin in the culture supernatants by thin-layer chromatography analysis. Saccharification capability of the isolates, assessed through ${\alpha}-amylase$ and glucoamylase activities, revealed that two isolates, TNA24 and TNA15, showed the highest levels of activity. Although the degrees of variation in ${\alpha}-amylase$ and glucoamylase activities among the isolates were higher, there were only slight differences in acid protease activity among the isolates with two, TNA28 and TNA36, showing the highest activities. Furthermore, statistical analyses showed that ${\alpha}-amylase$ activity was positively correlated with glucoamylase activity (p < 0.001), and therefore screening for either was sufficient to predict the saccharifying capacity of the Aspergillus strain.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.90-99
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• 2016

This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability of starter culture and phenolic compounds. In particular, the increase in the counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was highest (2.95 and 1.14 Log CFU/mL respectively) in DK yogurt. Furthermore, supplementation of the plant extracts significantly influenced to increase the antioxidant activity and water holding capacity and to produce volatile compounds. The higher antioxidant activity and water holding capacity were observed in NN yogurt than DK yogurt. Moreover, all of the sensory characteristics were altered by the addition of plant extracts. Addition of plant extracts increased the scores related to flavor, taste, and texture from plain yogurt without a plant extract, as a result of volatile compounds analysis. Thus, the overall preference was increased by plant extracts. Consequently, supplementation of DK and NN extracts in yogurt enhanced the antioxidant activity and physical property, moreover increased the acceptability of yogurt. These findings demonstrate the possibility of using plant extracts as a functional ingredient in the manufacture of herbal yogurt.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.12
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• pp.1832-1838
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• 2010

The objective of this study was to improve the flavor of Cheonggukjang prepared by the culture optimization of starter with the fibrinolytic activity. After 25 strains isolated from the commercial Cheonggukjang and Doenjang in different regions were compared, 7 Bacillus strains with proteolytic and slime-producing activities were selected. When the fibrin plate method for fibrinolytic activity was applied, CJJN-4 and 5 showed the higher activity in tripticase soy broth (TSB). All Cheonggukjang prepared with CJJN-4 and 5 also had the fibrinolytic activity, regardless of culture temperature or time. Especially, Cheonggukjang prepared at $40^{\circ}C$ showed higher activity than $45^{\circ}C$, and Cheonggukjang prepared with CJJN-4 for 48 hr at $40^{\circ}C$ showed the highest fibrinolytic activity. Although there was no significant difference in pH of Cheonggukjang prepared with CJJN-4 or 5 during 72 hr at $40^{\circ}C$, Cheonggukjang prepared with CJJN-4 at $45^{\circ}C$ had lower pH until 60 hr than $40^{\circ}C$ or CJJN-5. The total amino type nitrogen contents of Cheonggukjang were 1,139.6 (CJJN-4) and 1,027.6 mg% (CJJN-5) for 72 hr at $40^{\circ}C$, and their producing rates were also higher at $40^{\circ}C$ fermentation than $45^{\circ}C$. Meanwhile, the contents of ammonia type nitrogen induced unpleasant flavor were lower in Cheonggukjang with CJJN-4 and 5 at $40^{\circ}C$ than CJJN-5 at $45^{\circ}C$. Therefore, Cheonggukjang fermented with CJJN-4 starter at $40^{\circ}C$ had the improved flavor, such as change of amino or ammonia type nitrogen production, and higher fibrinolytic activity.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.4
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• pp.247-253
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• 2014

In the silage quality, the process of fermentation and use of micro-organism as starter cultures are crucial. The present study investigated the effect of homo and heterofermentative lactic acid bacteria as a starter culture strain on the silage quality and its aerobic stability using meta-analysis. Total 19 studies were used in the analysis. According to the strains of lactic acid bacteria used, experimental groups were assigned to heterofermentative (HEL), mixture of hetero and homofermentative (HHO), homofermentative (HOL) and various homofermentative (HOM). In each experimental group, standardized result of the treatment (with inoculant) was compared with the control (without inoculant) using risk ratio calculation method. The effect of experimental group was also compared. Different starter culture strains did not influence on silage pH and propionic acid production. However, lactic acid and acetic acid production were significantly (p<0.05) influenced by the start culture strains. HOM showed the greatest lactic acid production and HEL was the lowest. In contrast, HEL showed the greatest in acetic acid production and HOM and HOL were the lowest. In terms of ammonia nitrogen, HHO produced more (p<0.05) than the rest of the treatment. In crude protein and water soluble carbohydrate contents, there were no significant effects among treatments. Different strain of lactic acid bacteria significantly influenced on the effect of aerobic stability (p<0.05). Use of heterofermentative showed greater aerobic stability and the use of homofermentative lactic acid bacteria.

• The Korean Journal of Food And Nutrition
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• v.15 no.1
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• pp.42-50
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• 2002

This experiment was carried out to investigate the effect of Maesil extract on the acid production and growth of yoghurt starter in the skim milk medium. The Maesil extract was added to skim milk medium fur 1% to 9% and the medium was fermented by single or mixed culture of 4 types of lactic acid bacteria(Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus, bulgaricus, Lactobacillus casei). The chemical composition of Maesil, the changes in acid production (titratable acidity, pH) and number of viable cells of the medium during lactic fermentation in skim milk added with Maesil extract, and the keeping quality of curd yoghurts containing Maesil extract have determined. The composition of Maesil were 0.4% crude ash, 4.1% dietary fiber, 4.66%l citric acid, 0.264% total sugars and 405.34mg% vitamin C. The addition of Maesil extract stimulated the acid production and propagation of the lactic acid bacteria. Among the treatments tested, the addition of 3% Maesil extract with the mixed culture of Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus casei produced the highest amount of acid(1.23%) and showed the highest number of viable cell counts(3.6$\times$10$^{11}$ cfu/mL). When the curd yoghurts containing 3% Maesil extract with the mixed culture of the lactic acid bacteria were kept at 4$^{\circ}C$ and 2$0^{\circ}C$ for 30 days, it was showed that the changes of titratable acidity, pH and number of viable cell counts of the lactic acid bacteria were not significantly different during storage. Therefore the keeping quality of the curd yoghurts adding 3% Maesil extract showed relatively good at the shelf-life.

• Food Science and Preservation
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• v.24 no.5
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• pp.576-584
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• 2017

With the goal of developing a new functional fermentation milk using green tea powder (GP), milk was fermented with direct vat set (DVS) starter culture containing Streptococcus salivarius subsp. thermophilus, Lactobacillus paracasei and L. delbrueckii subsp. bulgaricus. We investigated fermentation characteristics and antioxidative activities of fermented milk supplemented with different concentrations (0.5, 1, 2, 3%) of GP. All samples were evaluated for pH, total acidity, viable cell count, and sugar contents. The pH of all samples decreased during fermentation, and the final pH ranged from 4.35 to 4.51. The acidity increased during fermentation, after the fermentation was completed, the titratable acidity was 0.8 to 1.1%. And viable cell count of all samples increased during fermentation, and the final viable cell count was 8.57 to 8.89 log CFU/mL. The sugar content decreased as the fermentation proceeded and finally reached 12 to $13^{\circ}Brix$. And increasing GP, decreased brightness and increased yellowness. Increasing GP concentration added to milk, improved DPPH free radical scavenging activity and ferric ion reducing activity of fermentation milk. The fermentation milk kept their pH, total acidity and viable cell counts standard of fermentation milk during the storage period at $4^{\circ}C$. These findings confirmed the possibility of development of the novel functional fermentation milk through the investigation of the quality characteristics of the fermentation milk added with GP.