• Applied Biological Chemistry
• /
• v.38 no.6
• /
• pp.507-511
• /
• 1995

In an attempt to improve the productivity of ${\beta}-galactosidase$ from Bacillus sp. A1, which was isolated from soil and has remarkably higher transgalactosylation activity than lactose hydrolysis activity, a chemical mutation procedure using N-methyl-N'-nitro-N-nitrosoguanidine followed by selection was conducted. The final selection, designated as Bacillus sp. A4442, turned out to show a substantially increased enzyme productivity. Catabolite repression by glucose and lactose requirement as an inducer for the enzyme biosynthesis, which were shown in the parent strain, was markedly diminished; instead it was found out that galactose acts as another inducer. Because pH of medium, one of the most important factors for cell growth as well as enzyme production, is closely related with the sugar concentration during culture, it was kept in the optimum range of $6.5{\sim}7.5$; for this the initial glucose concentration was adjusted to be 0.5% which was thereafter maintained by the controlled pumping-in of lactose using the pH-stat technique. By doing so, we were able to increase the productivity of ${\beta}-galactosidase$ with high transgalactosylation activity up to $44\;unit/m{\ell}-broth$.

• Food Science and Preservation
• /
• v.20 no.5
• /
• pp.744-750
• /
• 2013

The indigenous Saccharomyces cerevisiae strains S13 and D8 were isolated at the microbial succession stage during spontaneous fermentation of Campbell Early wine as a resistant to potassium metabisulfite and a high sugar concentration. In this study, the fermentation characteristics of Campbell Early wine were investigated and compared with those of S. cerevisiae W-3, an industrial wine yeast. Alcohol production by the two strains was delayed at the initial fermentation stage, but increased fast when the fermentation continued. After the fermentation, the S13 and D8 wines contained 12.6% and 13.2% (v/v) alcohol, respectively, which were significantly higher than the alcohol content of the W-3 wine (12%, v/v). No marked differences were observed in the residual soluble solid content and the pH. However, the S13 and D8 wines showed high levels of total acid content, including malic and lactic acids. Especially, the lactic acid content was 8.9-fold in the S13 wine and six-fold in the D8 wine, compared with that of the W-3 wine. The two strains produced a higher level of acetaldehyde and a lower amount of methanol in the wine than the W-3 strain. The iso-Butanol content was lower in the two indigenous yeast wines with similar levels of n-propanol and iso-amyl alcohol contents than that in the W-3 wine. In the sensory evaluation, the S13 and D8 wines had higher scores for their color, flavor, taste and overall preferences than the W-3 wine. Especially, the S13 and D8 wines had much higher scores than the W-3 wine for flavor and color, respectively.

• The Korean Journal of Food And Nutrition
• /
• v.16 no.4
• /
• pp.410-416
• /
• 2003

Three varieties of soybean were acidified by soaking in two kinds of vinegar which were persimmon vinegar and brewed vinegar. Chemical properties of soaking solution and physical and organoleptic properties of soybean during soaking at room temperature for 8 days were studied. The soybeans were acidified in vinegar solution at room temperature for 8 days. The results showed that soybean weight was rapidly increased until first two days and then gradually increased thereafter. Increase in total acidity and sugar concentration and decrease in pH of vinegar solution were also measured during initial soaking stage. The changes in pH and acidity were more significant in brewed vinegar than those in persimmon vinegar, The L values of persimmon vinegar solution after soaking the soybean were relatively lower than that of brewed vinegar. The a values of the vinegar solution used for black beans were increased while that of the vinegar solution used for white beans were decreased, The flavor and texture of acidified bean in persimmon vinegar were more soft and less benny than those acidified in vinegar. However sourness of the acidified beans in persimmon vinegar was much softer higher to those values of brewed vinegar.

• Journal of Nutrition and Health
• /
• v.6 no.3
• /
• pp.1-8
• /
• 1973

Metabolic responses to the protein-free, high-carbohydrate diet and subsequent food restriction on the same diet at the level of 50% and 75% has been studied on the adult albino rats. The energy source was either corn starch or sugar. In experiment I, adult male rats weighing $509{\pm}8g$ were divided into two groups 10 rats each. Rats fed on the stock diet served as a control. Rats of restriction group received a protein free diet until they reduced their weight down to 400g and continue on a protein-calorie restriction diet until they reduced their weight down to 300g. In experiment II, 28 adult male rats and the same numbers of female rats weighing $329{\pm}5g$ and $223{\pm}4g$ respectively were divided into four groups, 7 males and females in each. Rats fed on a stock diet were sacrificed at the point when others started a protein free diet. These were served as the control. The protein free group received a protein free diet ad libitum for 4 weeks. The 50% restriction group and 75% restriction group were fed on a protein free diet coupled with food restriction at levels of 50% and 75% respectively for 3 weeks. In the result of this study: 1. The rate of body weight changes was similar between the males and the females. Feeding protein free diet ad lib. initiated a rapid weight lost of approximately 25% and protein free diet coupled with food restriction showed 37-43% reduction of their initial weight. 2. There was no significant differences in the value of the N concentration in liver, spleen, brain and muscle between controls and experimental groups. 3. Rats fed on protein free diet showed 1/10 value of the control in the nitrogen excretion in urine. However female showed less N excretion than male. 4. Observing blood picture, the effects of protein depletion and calorie restriction were not appeared any remarkable changes. 5. There was no sign of fatty liver which might result from protein depletion and calorie restriction. 6. Following semi-starvation, FAO and HMP-DH total enzyme activity was reduced, but activity per unit weight was relatively stable.

• Food Science and Preservation
• /
• v.17 no.1
• /
• pp.36-41
• /
• 2010

Fermentation characteristics of yakju prepared with addition of Opuntia ficus indica were examined, with respect to the nature and concentration of additional added materials. The pH level began to decrease after the secondary brewing stage and the total acid content increased during fermentation. The level of reducing sugars in yakju prepared with Opuntia ficus indica increased at the first brewing stage and then slowly decreased after 4 days of fermentation. The ethanol content of supplemented yakju rapidly increased during the initial 6 days of fermentation, to a maximum content of 17.1% after 14 days. The free sugar content was higher in yakju fermented with Opuntia ficus indica stem compared with fruit. The level of organic acids increased as the amount of Opuntia ficus indica material increased. Organic acid level increased during fermentation and lactic acid was the main organic acid in yakju fermented with Opuntia ficus indica. Sixteen volatile compounds were found by GC-MS in supplemented yakju. The most prominent volatile component was iso-amyl alcohol, followed by butyl alcohol and methyl esters. The DPPH radical-scavenging activity of yakju fermented with Opuntia ficus indica stem was higher than when yakju was prepared with fruit. Sensory scores of yakju fermented with 20% (w/v) fruit and 10% (w/v) stem were greater than those of yakju prepared by other treatments.

• Korean Journal of Food Science and Technology
• /
• v.28 no.4
• /
• pp.650-656
• /
• 1996

Quality changes of salted Chinese cabbage with different package pressure and storage temperature were examined during 7-day storage. Each storage yield for 7 days at $0^{\circ}C$ was $87.1{\%}$ in AP (atmospheric pressure) and 83.1% in LP (low pressure). Initial salinity was 2.62 in AP and 2.05 in LP and their changes during the storage were very small. In AP the pH slowly decreased to 5.66 after 7-day storage at $0^{\circ}C$ but rapidly decreased to 4.08 at $20^{\circ}C$. Concentration of reducing sugar in LP was higher than that in AP, as more juice was exuded in LP than in AP. The compression force of salted Chinese cabbage changed slowly at $0^{\circ}C$ and constantly increased at $20^{\circ}C$ during the storage, but decreased in LP. The amount of exuded juice was small in AP but large in LP. Quality changes of salted Chinese cabbage was minimum in AP at $0^{\circ}C$ during the 7-day storage.

• Korean journal of food and cookery science
• /
• v.30 no.4
• /
• pp.435-443
• /
• 2014

In this study, we investigated the quality characteristics of Korean soybean paste, Doenjang, fermented for 6 weeks at room temperature with the addition of 0, 10, 20 and 30% garlic. Samples were analyzed in one-week intervals. The lightness decreased in all samples as the fermentation period and garlic concentration increased. Yellow index decreased in weeks 5~6 compared with weeks 0-1, for which the values were lower for the garlic-added Doenjang than the control. The pH increased, greatly reducung the acidity in week 1 compared with week 0. Significant differences in the pH and acidity were not observed among the sample groups. Amino type nitrogen contents increased continuously up to weeks 5, displaying no significant differences among the sample groups at weeks 5 and 6. In addition, reduction in the sugar content increased depending on the fermentation period. It increased in all sample groups by about 2.5 times after 6 weeks compared with the initial levels. Isoflavone content was also reduced generally depending on the fermentation period. In the early fermentation periods, the aglycone contents were the higher than the glycosides, while the glycoside contents increased over the fermentation period. The presence of Bacillus was not significantly different among the garlic added groups, but yeast was lower in the Doenjang with high garlic content.

• Journal of the Korean Society of Food Culture
• /
• v.9 no.2
• /
• pp.125-130
• /
• 1994

This study was intended to observe the effect of the addition of soused shrimp(5%, 10%) and/or cooked glutinous rice flour(2.5%) on the changes of low molecular nitrogen compounds content of Kimchi during fermentation at $10^{\circ}C$ for 14 days. The pH, total acidity, free sugar, nitrite, dimethylamine(DMA) and volatile basic nitrogen(VBN) contents were measured. The nitrite contents were approximately 0.16 to 1.31 mg/Kg at the inital stage of fermentation. It was found that the nitrite contents of Kimchi samples with 10% soused shrimp$(S_2,\;GS_2)$ were relatively high among the Kimchi samples. However, nitrite was not detected after the stage of optimum maturity in all Kimchi samples. The dimethylamine(DMA) content of Kimchi samples were increased during the fermentation with increasing the soused shrimp concentration. Cooked glutinous rice flour enhanced the DMA production of Kimchi with soused shrimp. DMA content were 0.93-1.2 mg/kg at initial stage end 1.6-2.26 mg/kg at final stage of fermentation of the Kimchi with soused shrimp. As the fermentation period increased, the VBN contents of Kimchi samples with soused shrimp$(S_1,\;S_2,\;GS_1,\;GS_2)$ were apparently higher than those of Kimchi samples without it(C, G). Though the soused shrimp enhanced the volatile basic nitrogen production but cooked glutinous rice did not affected VBN production during Kimchi fermentation.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.6
• /
• pp.1026-1032
• /
• 2015

This study attempted to find an efficient method for the preparation of high-purity galactooligosaccharides (HP-GOS) using ${\beta}$-galactosidase and yeast fermentation. GOS prepared using Lactozym 3000L showed the greatest enhancement in total GOS of the six ${\beta}$-galatosidases tested. GOS alone achieved 51% conversion of initial lactose. GOS production was enhanced by fermentation with commercial yeast (Saccharomyces cerevisiae); its concentration reached 71% after 36h fermentation with 8% yeast. Component sugar analysis with HPLC indicated that HP-GOS fermented with S. cerevisiae showed significantly increased levels of 4'/6'-galactosyllactose and total GOS as well as a significantly decreased glucose level. HP-GOS facilitated the growth of Lactobacillus sp. (L. acidophilus and L. casei) and Bifidobacterium sp. (B. longum and B. bifidum). In sum, high-purity GOS has been successfully produced through both an enzymatic process and yeast fermentation. GOS encourages the growth of bacteria such as Lactobacillus and Bifidobacterium that may be beneficial to human gastrointestinal health.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.3
• /
• pp.366-370
• /
• 2007

Wild grapes contain various organic acids, vitamins, and inorganic salts compared to other various fruits. Their anthocyanin compounds are also known to have excellent effects in preventing cancers and heart diseases. Wild grapes are supposed to be a superior material for wine fermentation. This study was performed for searching optimum conditions for producing wild grape wines to improve their quality and taste. Four wild strains were isolated from Muscat Bailey A, ‘Kyoho’ grapevine, and wild grapes. For wild grape wine production, an optimum initial sugar concentration was $24^{\circ}Brix$ and an optimum temperature was $24^{\circ}C$. Sensory characteristics of the wild grape wine were evaluated for incense, sour taste, astringency, and sweet taste. Quality properties of the wild grape wine produced under the optimized fermentation conditions were analyzed. Total sugar, polyphenol contents, and acidity of the wild grape wine were 50.00 mg/mL, 25.30 mg/mL, and 0.95%, showing higher value than those of commercial grape wines. Amino acids, tannins, alcohol contents, and pH were 1.80 mg/mL, 1.88 mg/mL, 12%, and 3.59, respectively. The optimum fermentation conditions can be used to improve quality of the wild grape wine.