Seung-Mi Woo

Effect of Nuruk and Fermentation Method on Organic Acid and Volatile Compounds in Brown Rice Vinegar

The effects of different nuruk contents and fermentation methods (AV, vinegar fermented in an agitated culture; SV, vinegar fermented in a static culture) on organic acids and volatile compounds in brown rice vinegars were investigated. In the SV, the contents of acetic, oxalic, tartaric, and malic acids increased with hipher contents of nuruk. Acetic, tartaric, and malic acid contents were higher in the SV than those in the AV. Volatile compounds that can affect vinegar quality, including acetic acid, isoamyl acetate, phenethyl acetate, and phenethyl alcohol were present at high concentrations in the AV. With the increase in nuruk contents in the AV, acetic acid content decreased and isoamyl acetate and phenethyl acetate content increased. No significant differences in sensory scores were observed regarding the amount of nuruk and the type of fermentation. However, electronic-nose analysis showed its potential to effectively differentiate different samples.

Characteristics of Alcohol Fermentation of Citrus Fruit Hydrolysates

The present study investigated the alcohol fermentation characteristics of citrus fruit hydrolysates for the development of citrus fruit wine with enhanced functionality. The alcohol content of whole citrus (A) and removed peels citrus fruit (B) was 10.13% and 10.83%, respectively. The sugar content of (A) was 12.98Brix, which was slightly higher than that of (B) (11.38Brix), but no significant difference in the alcohol fermentation characteristics was observed. Although the hesperidin content was not largely affected by removed peels the narirutin content of (A) was increased to 281.31 μM, which was significantly higher than that of (B) (199.05 μM). Thus, the whole citrus was used for fermentation. Investigation of alcohol fermentation characteristics based on yeast type found that the maximum alcohol content was 12.75% when S. bayanus EC-1118 was used. The alcohol content reached 12.40% at an initial acidity of 0.2%, but when the initial acidity was higher than 0.2%, the alcohol content was slightly decreased. At an initial sugar content of 22°Brix, the alcohol content was 11.65%, and the maximum alcohol content of 12.85% was observed when at an initial sugar content of 24 o Brix.