Quality effects different process treatments on the antioxidant properties of black soybean and the quality of black soybean beverage

• Main Author: 王聖文
• Other Authors: 許成光
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/86692114787951767779

碩士 === 國立嘉義大學 === 食品科學系研究所 === 103 === Our previous study indicated that the water extract of black soybean had protective effect against carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. This study intended to investigate the effects of preheating, extraction solvents, sterilization and storage on the quality of black soybean tea. Preheated (130℃, 5 min) whole soybean, seed coat and seed kernel were extracted with hot water, 80% ethanol and 80% acetone; the extracts were subjected to the tests of DPPH and ABTS˙+ radicals scavenging activity, reducing power, total phenol and total anthocyanins contents. Individual anthocyanin content (cyaniding-3-glucoside (C3G), delphinidin-3-glucoside (D3G) and peonidin-3-glucoside (P3G)) in the extracts was also determined using HPLC. The results showed that the acetone extract from preheated seed coat had the highest ABTS˙+ radical scavenging activity, reducing power and total phenol content, while the ethanol extract from preheated seed coat had the highest DPPH radical scavenging activity and total anthocyanin content. HPLC analysis also found that the ethanol extract from preheated seed coat had the highest C3G content. Although ethanol or acetone extraction resulted in higher antioxidant than hot water extraction, for safety and convenience, we still chose hot water extraction to produce black soybean beverage. Preheated and un-preheated black soybeans were soaked at hot water for 20 min (w/v 1 : 10), sterilized at 121℃ for 15 min, and then packed in a 240 mL can container or glass container. For can package, a degassing process using steam for 20 min was conducted prior to the sterilization process. There were four beverages: Cun and Gun (un-preheated black soybean beverage at can container and glass container, respectively), and C130 and G130 (preheated (130℃, 5 min) black soybean beverage at can container and glass container, respectively). The black soybean beverages were stored at room temperature for eight weeks and the quality of the beverages was evaluated at week 0, 2, 4 and 8. It was found that DPPH radical and ABTS˙+ radicals scavenging activities of the beverages decreased during storage, but the change of reducing power was not significant. The total phenol content decreased slightly during storage. The total anthocyanin content close to 0 after sterilization, and anthocyanin analysis by HPLC, the result is the same with total anthocyanin. The L*, a*, b* are increased after sterilization. The pH values are decreased after sterilization. The HPLC analysis conformed that the sterilization process destroyed C3G in the beverages. The sterilization process increased the L*, a*, b* but decreased the pH values of the beverages. Moreover, the clarity of the beverages decreased after sterilization, but increased during subsequent storage. A sensory evaluation of the beverages stored at room temperature for 4 week indicated that Cun beverage had the highest scores in overall acceptability. Black soybean has protective function against chemical induced liver damage, and the beverage still maintains high antioxidant activity after sterilization and 8 week storage; therefore, it has the potential of becoming a health beverage.