发酵和加工对桑椹抗氧化和降血糖作用的影响

目的：研究发酵和加工处理对桑椹抗氧化和降血糖作用的影响。方法：测定桑椹原粉（mulberry powder，MP）、桑椹发酵液（fermented mulberry，FM）、桑椹发酵液冻干粉（freeze-dried fermented mulberry，D（FM））、桑椹发酵液添加黄豆辅料后的冻干粉（freeze-dried fermented mulberry mixed with soybean，D（FM＋S））的单糖含量、菌落总数以及2,2’-联氨-双-3-乙基苯并噻唑啉-6-磺酸（2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate)，ABTS）阳离子自由基、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl，DPPH）自由基、羟自由基清除率和亚铁离子螯合能力、α-葡萄糖苷酶抑制率的变化。结果：桑椹经发酵、冷冻干燥处理后，基本检测不到果糖和葡萄糖；D（FM）中肠膜明串珠菌和酵母菌的存活率分别为54.77%、53.40%，而D（FM＋S）中两种菌的存活率都达到90%以上，说明添加黄豆辅料减少了冷冻干燥过程中益生菌的损失。ABTS阳离子自由基清除能力由强到弱依次为D（FM）＞D（FM＋S）＞MP＞FM；DPPH、羟自由基清除率以及亚铁离子螯合能力呈现出一致的趋势：D（FM）和D（FM＋S）清除能力最强，其次为MP，FM最弱。MP、FM、D（FM）、D（FM＋S）对α-葡萄糖苷酶的半抑制浓度分别为0.58、0.53、0.19、0.31 mg /mL，D（FM）和D（FM＋S）对α-葡萄糖苷酶的抑制效果优于MP和FM。结论：桑椹发酵和加工处理得到的冻干粉抗氧化能力和降血糖作用都比FM和未发酵的MP强。

Effect of Fermentation and Processing on Antioxidant and Hypoglycemic Activity of Mulberry Fruit

Objective: To study the effect of fermentation and processing on the antioxidant and hypoglycemic activity of mulberry fruit. Methods: The monosaccharide content, microbial populations and scavenging capacity against 2,2’-azinobis- (3-ethylbenzthiazoline-6-sulphonate) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals, ferrous ion chelating power and alpha-glucosidase inhibitory activity of mulberry powder (MP), fermented mulberry (FM), freeze-dried fermented mulberry (D (FM)) and freeze-dried fermented mulberry mixed with soybean (D (FM + S)) were determined. Results: After fermentation and freeze-drying of mulberry, its fructose and glucose levels decreased to zero. The survival rates of Leuconstoc mesenteroides and Saccharomyces cerevisiae in D (FM) were 54.77% and 53.40%, respectively, while those in D (FM + S) were both more than 90%, implying that the presence of soybean resulted in reduced loss of probiotics during the freeze drying process. The ABTS radical scavenging capacity of these samples followed the decreasing order of D (FM) > D (FM + S) > MP > FM. Consistent trends were observed for DPPH and hydroxyl radical scavenging capacity and ferrous ion chelating power. Both D (FM) and D (FM + S) were ranked the highest, followed by MP, and FM was the weakest. The IC50 values for inhibition of alpha-glucosidase by MP, FM, D (FM) and D (FM + S) were 0.58, 0.53, 0.19 and 0.31 mg/mL, respectively, which indicates that the inhibitory effect of D (FM) and D (FM + S) was better than that of the other samples. Conclusion: Frozen-dried fermented mulberry mixed with soybean has stronger antioxidant and hypoglycemic effects than both fermented and unfermented mulberry.