Quality characteristics of apple vinegar by using agitated and static cultures without any additive were compared. pH was reduced with passage of acetic acid fermentation time. Total acidity of the agitated culture vinegar (A) was 6.08% at the 8 day according to the progress of fermentation and that of the static culture vinegar (B) recorded 5.20% at the 60 day of fermentation. There was no significant difference in sugar content of (A) and (B). L value was lower in (B) than (A) but a and b values were higher in (B) than (A). Organic acid content of (A) was high only in acetic acid but malic, citric and succinic acids appeared high in (B). As free sugar, fructose and glucose were observed in both of them. In sensory examination results, (B) showed the highest taste and overall preferences. From all of these results traditional static culture are expected to be used to make high-quality vinegar.

This study was conducted to predict optimum leaching conditions for functional components of black tea. Two variables were used to determine the optimum leaching temperature and leaching time with a five-level central composite design and response surface methodology. Soluble solid, reducing sugar, total phenolics, and total flavonoid contents increased as leaching temperature and time increased. The ranges of maximum leaching conditions for these components were 78.28～87.08 o C and 3.97～4.27 min. Vitamin C level was maximal at 61.29 o C and 2.68 min. Electron donating ability showed the highest values at 68.30 o C and 0.54 min. Based upon the superimposed results, it was predicted that the optimal ranges of leaching conditions for some functional components from black tea were 63～79 o C for 1.5～2.1 min.