Seon-A Yoo

Biotransformation of major ginsenosides in ginsenoside model culture by lactic acid bacteria

Background Some differences have been reported in the biotransformation of ginsenosides, probably due to the types of materials used such as ginseng, enzymes, and microorganisms. Moreover, most microorganisms used for transforming ginsenosides do not meet food-grade standards. We investigated the statistical conversion rate of major ginsenosides in ginsenosides model culture during fermentation by lactic acid bacteria (LAB) to estimate possible pathways. Methods Ginsenosides standard mix was used as a model culture to facilitate clear identification of the metabolic changes. Changes in eight ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, and Rg2) during fermentation with six strains of LAB were investigated. Results In most cases, the residual ginsenoside level decreased by 5.9–36.8% compared with the initial ginsenoside level. Ginsenosides Rb1, Rb2, Rc, and Re continuously decreased during fermentation. By contrast, Rd was maintained or slightly increased after 1 d of fermentation. Rg1 and Rg2 reached their lowest values after 1–2 d of fermentation, and then began to increase gradually. The conversion of Rd, Rg1, and Rg2 into smaller deglycosylated forms was more rapid than that of Rd from Rb1, Rb2, and Rc, as well as that of Rg1 and Rg2 from Re during the first 2 d of fermentation with LAB. Conclusion Ginsenosides Rb1, Rb2, Rc, and Re continuously decreased, whereas ginsenosides Rd, Rg1, and Rg2 increased after 1–2 d of fermentation. This study may provide new insights into the metabolism of ginsenosides and can clarify the metabolic changes in ginsenosides biotransformed by LAB.

Quality Characteristics of Korean Black Raspberry Bokbunja Wines Produced Using Different Amounts of Water in the Fermentation Process

School of Life Science and Biotechnology, Korea UniversityAbstract In this study, we investigated the effect of the amount of water added prior to fermentation on the quality ofbokbunja (Rubus coreanus Miq.) wine produced. Water was added at 0-fold (A), 1-fold (B), 2-fold (C), 3-fold (D), and4-fold (E) of the fresh bokbunja weight (w/w), prior to fermentation. Although the amount of bokbunja wine obtained afterfermentation increased in proportion to the amount of water added prior to fermentation, the total acidity of the bokbunjawine, adjusted for the weight of bokbunja used in the fermentation process, increased. Moreover, the total phenol andflavonoid content (mg) per weight (g) of bokbunja, in (B), (C), (D), and (E) were 2.86-4.42 and 2.58-3.01 times higher,respectively, than those in (A). These data suggest that different types of bokbunja wines can be produced and differentcontents of total phenol can be obtained by simply changing the amount of water added prior to fermentation.Keywords: bokbunja, wine, water, total phenol, total flavonoid

Effectiveness of Yeast Nutrients on Stuck Fermentation of Blueberry Wine

In this study, we investigated the effect of various yeast nutrients on stuck and sluggish fermentation of blueberry wine. Sugar consumption rates during fermentation were observed after the addition of yeast extract, diammonium phosphate, yeast energizer, raisin, or banana to fermenting blueberry wine. After fermentation, the alcohol concentrations of wines containing yeast extract (14.1%) and banana (13.3%) were higher than those of wines containing diammonium phosphate (12.6%), yeast energizer (12.4%), and raisin (11.4%). Correspondingly, levels of soluble solids were lower in wines to which yeast extract (3.9 o Bx) and banana (2.5 o Bx) were added than in wines to which diammonium phosphate (4.6 o Bx), yeast energizer (4.6 o Bx), and raisin (6.3 o Bx) were added. Thus, we concluded that banana could be

Quality characteristics of fermented sausage prepared with soy sauce

The contributions of soy sauce to the quality characteristics of fermented sausages were investigated. The number of lactic acid bacteria in sausages prepared with soy sauce increased from the first day of fermentation, and the population reached approximately log 7 CFU/g by the 5th day of fermentation. The pH decreased sharply to 5.0-5.1 by the 5th day of fermentation, in accordance with the dramatic increase of titratable acidity. After 36 days of fermentation, the levels of total organic acids and amino acids in soy sauce sausages increased to 3,026.3-3,116.4 mg/100 g and 1,132.2-1,172.8 mg/100 g respectively, and this level was even higher than those of the sausage fermented with a starter culture. 2% soy sauce sausage also showed higher values of hardness, chewiness, and smoke odor than the control. These results suggest that soy sauce has great potential as an alternative starter culture and additive for the quality improvement of fermented sausages.

A GC-MS based metabolic profiling of fermented sausage supplemented with pineapple

A GC-MS based metabolomic study was performed to understand metabolic changes during sausage fermentation and to investigate how the incorporation of pineapple affects the metabolic profiles of fermented sausages. Principal component analysis models showed clear metabolic differences among the fermented sausages according to the fermentation periods and the pineapple addition. Increased amounts of amino acids and organic acids except for citric acid, along with decreased levels of sugars were observed after fermentation. Higher levels of sugars and citric acid in the pineapple supplemented sausages dramatically decreased during the early stage of fermentation. The contents of lactic acid, phosphoric acid, succinic acid, ribonic acid, valine, leucine, isoleucine, glycine, threonine, glutamic acid, glucose, and sucrose were significantly increased in the 2% pineapple addition sausages. GC-MS and PCA analytical methods provide a new approach to understand of the metabolic changes in fermented sausages during fermentation.