Studies on the analysis and antioxidative activities of lignans and lignan glycosides in sesame meal

• Main Authors: Yung-Shin Shy, 徐永鑫
• Other Authors: Lucy Sun Hwang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/44266622631974692286

博士 === 國立臺灣大學 === 食品科技研究所 === 89 === Abstract Most of the sesame oil is produced by roasting and pressing of the sesame seeds. After high temperature of roasting, the sesame meal is bitter tasted and the protein was highly denatured. Therefore, the sesame meal is generally used as feeds or fertilizers. However, lignans and lignan glycosides of sesame meal are found to have several functional effects. The purpose of this project was to study (1) the change of the contents of lignans and lignan glycosides versus the ingluence of the antioxidative activity during the roasting process (2) the antioxidative activity of the unroasted defatted sesame meal, aiming at finding the components responsible for its antioxidative activity (3) the effect of enzymatic and acid hydrolysis on the antioxidative activity of lignan glycosides crude extract of unroasted sesame meal. We hope that we can increase the amount of functional components and enhance the utilization of sesame meal. Burma black sesame was used as the experimental material in this study. In sesame lignans, the contents of sesamin and sesamolin were 2.164 and 1.380 mg/g seed, respectively; in sesame lignan glycosides, the contents of sesaminol triglucoside and sesaminol diglucoside were 1.731 and 0.084 mg/g seed, respectively. Sesaminol monoglucoside was not detected in sesame seeds. Increasing the roasting temperature from 160℃ to 240℃, the content of sesamin didn’t change significantly. The content of sesamolin was decreased from 7.04 mg/g oil (unroasted) to 0.14 mg/g oil (roasted at 240℃ fro 20min), with a decreasing rate of 93.145. Meanwhile, the content of sesamol was significantly increased. The oxidative stability of sesame oil was also significantly increased while the roasting temperature was increasing. It might be due to the increasing of sesamol and maillard reaction products. With regard to the DPPH free radical scavenging effect and Cu+2-induced oxidation of human LDL assay, the unroasted crude extract of lignan glycosides had the poorest antioxidative activity. Under the roasting temperature from 160℃ to 240℃, the antioxidative activity were increased with increasing temperature. The increment of the antioxidative activity of crude extract of lignan glycosides was probably due to the total phenolics contents and maillard reaction products formed during the roasting process. The most abundant lignan glycosides of Burma black sesame were sesaminol triglucoside and sesaminol diglucoside. Neither sesaminol triglucoside nor sesaminol diglucoside showed good antioxidative activity toward DPPH free radical scavenging effect and inhibition of LDL oxidation. In this study, we found that the brown materials isolated from Fr2 showed excellent DPPH free radical scavenging effect and also had pronounced inhibitory effect toward the oxidation of human LDL. It was suggested that the brown materials plays a prominent role in the antioxidative activity of the lignan glycosides crude extract. Identification of the responsible components is underway. 10 mg of lignan glycosides crude extract (from unroasted sesame meal) was hydrolyzed with 7 mg of cellulase and 6 mg of β-glucosidase at 50℃ for 48 hour. The hydrolysates showed a better DPPH free radical scavenging effect. At the concentration of 100 μg/mL, the scavenging effect was 2.12 fold higher than that of the unhydrolyzed one. In the case of acid hydrolysis with HCl aqueous solution from 0 to 2N, we found that when the lignan glycosides crude extract was hydrolyzed with 0.5N HCl for 30 min, the hydrolysates showed the best DPPH free radical scavenging effect. The scavenging effect was 1.55 fold higher than that of the unhydrolyzed one when the concentration of hydrolysates was 100μg/mL. The possible might be due to the formation of sesaminol during the hydrolysis process.