沙棘原浆苹果酸-乳酸发酵过程中理化指标及抗氧化能力的变化

Changes in physical and chemical indicators and antioxidant capacity of sea buckthorn puree during malolactic fermentation

以沙棘原浆为原料,利用酒酒球菌CICC 6066进行苹果酸-乳酸发酵(malolactic fermentation, MLF),研究发酵过程中(25℃,8 d)沙棘原浆活菌数、pH值、有机酸、单糖、黄酮醇、酚酸及超氧化物歧化酶(superoxide dismutase, SOD)和抗氧化活性的变化。结果表明,酒酒球菌发酵显著提高了沙棘原浆pH值,降低其可溶性固形物、总酸和总糖的含量;发酵8 d后,沙棘浆有机酸组成比例发生明显变化,苹果酸及柠檬酸含量显著降低,其中苹果酸降解率为86.01%,而乳酸含量增加了4.79倍;发酵后沙棘浆中所含的葡萄糖和果糖分别降低23.25%和32.17%;MLF后沙棘浆的总黄酮醇和总酚酸分别增加了49.35%和29.63%,总量达到160.71 mg/L;相比未发酵沙棘原浆,发酵沙棘浆的SOD活力及抗氧化能力(·OH、DPPH自由基、ABTS阳离子自由基和·O;清除能力及总抗氧化能力)均显著增强。综上,酒酒球菌可在沙棘原浆中进行充分的MLF,有效降低沙棘原浆苹果酸含量,改善沙棘原浆的口感,并通过发酵进一步提高其生物功效。

Malolactic fermentation(MLF) of sea buckthorn puree by Oenococcus oeni was investigated. The following parameters were reviewed throughout the MLF at 25 ℃ for 8 days: viability of cells;pH;organic acid, monosaccharide, flavanol, and phenolic acid content;and superoxide dismutase(SOD) and antioxidant activities of the puree. After fermentation by O.oeni, the pH of sea buckthorn puree increased, while soluble solid, total acid, and total sugar content decreased. The organic acid composition of sea buckthorn puree also changed significantly. For example, malic and citric acid concentrations decreased, with the total degradation of malic acid being 86.01%, while lactic acid concentration increased by 4.79-fold by day 8 of fermentation. After fermentation, glucose and fructose content in sea buckthorn puree decreased by 23.25% and 32.17%, respectively. Total flavanol and total phenolic acid levels increased by 49.35% and 29.63%, respectively, with the combined total concentrations reaching 160.71 mg/L. Compared with non-fermented sea buckthorn puree, sea buckthorn puree subjected to MLF showed increased SOD activity(assessed by the superoxide radical scavenging capacity) and total antioxidant capacity, as determined by DPPH free radical and ABTS cation ion free radical assays. This study showed that O.oeni could induce sufficient MLF in sea buckthorn puree to effectively reduce its malic acid content and improve its taste and biological efficacy.