辣木叶提取液在发酵过程营养成分及其抗氧化活性的变化

以辣木叶为原料,经过提取浓缩得到辣木叶提取液,利用植物乳杆菌S35作为发酵菌株,在接种量为1%,发酵温度为37℃的条件下培养72 h,对发酵过程中基本理化性质(pH、可溶性固形物、总酸),营养成分(还原糖、黄酮、多酚、有机酸),体外抗氧化活性(DPPH清除能力,羟自由基清除能力,超氧阴离子清除能力)进行了研究。结果表明,在整个发酵过程中,p H和可溶性固形物呈下降趋势,总酸呈现上升的趋势。还原糖随发酵时间的增加整体呈下降的趋势,黄酮、多酚先升后降,在发酵24 h和32 h达到最高,含量分别为223.11 mg/L和106.00 mg/L。有机酸中草酸无明显变化,柠檬酸,琥珀酸,丙酮酸,乙酸均有下降,乳酸随发酵时间的延长先急剧增加,后略有下降,在发酵40 h达到最高,含量为135.43 mg/L。在发酵过程中,DPPH清除能力、羟自由基清除能力和超氧阴离子清除能力在发酵32 h、8 h和32 h到达最高,清除率分别为89%、64%和60%。结论:乳酸菌发酵能提高辣木叶提取液中黄酮和多酚含量以及抗氧化活性,本研究将为辣木发酵制品的研发提供了技术指导。

Changes of Nutritional Components and Antioxidant Activities of Moringa oleifera Leaf Extract during Fermentation

Moringa oleifera leaf extract was extracted from Moringa oleifera leaves.It was used as fermented substrate and Lactobacillus plantarum S35was used as a fermentation strain,the fermentation conditions were obtained with the fermentation temperature of 37℃,the fermentation time of 72h,the inoculum size of 3%,and the change of the basic physicochemical properties(pH,soluble solids,total acid),nutrient composition (reducing sugar,flavonoids,polyphenols,organic acids)and antioxidant activity (DPPH scavenging ability,hydroxyl radical scavenging ability,superoxide anion scavenging ability)of Moringa oleifera during the fermentation process of lactic acid bacteria were determined.The results showed that pH and soluble solids decreased,and the total acid increased during the whole fermentation process.The reducing sugar was observed a decreasing trend generally with the increase of fermentation time.The contents of flavonoids and polyphenols first rise and then decreased,and reached the highest at 24h and 32h after fermentation,with contents of 223.11mg/L and 106.00mg,/L, respectively.The oxalic acid was no found to be a significant change,but citric acid,succinic acid,pyruvic acid,and acetic acid continuously decreased.Lactic acid increased rapidly and then decreased slightly,and reached the highest at 40h after fermentation,with contents of 135.43mg/L.DPPH scavenging ability,hydroxyl radical scavenging ability and superoxide anion scavenging ability reached the highest at 32h,8h and 32h ,and the scavenging rates were 89%,64% and 60%,respectively.In the study,it was demonstrated that fermentation of Lactobacillus was able to enhance the contents of flavonoids and polyphenols and antioxidant activity in Moringa oleifera leaves extract.