本研究使用从红甜菜自然发酵液中分离鉴定出的乳酸肠球菌和植物乳杆菌分别对红甜菜浆和红甜菜片进行发酵，测定了48 h发酵过程中pH、总酸、活菌数、总酚含量、黄酮含量、总抗氧化能力、DPPH·清除能力、ABTS+·清除能力的变化。结果显示：发酵后的红甜菜浆和红甜菜片的pH显著下降（p<0.05），最低达3.95；总酸含量有所增加，最高达16.78 g/kg；使用乳酸肠球菌发酵的红甜菜浆活菌数最高为7.17 log(cfu/L)；乳酸肠球菌发酵样品中总酚含量提升幅度最大，相对未发酵样品，其发酵浆总酚含量达755.30 mg/L，提高了72.55%；使用植物乳杆菌发酵的红甜菜片中黄酮含量最高为0.92 mg/L，增加了113.95%；植物乳杆菌发酵的红甜菜浆的甜菜红素含量下降最快，相比未发酵液降至6.01 mg/100 mL，下降38.10%，而红甜菜片发酵液中结果相反，甜菜红素含量分别增加128.81%和137.71%；各样品中的甜菜黄素均在发酵前半段显著提高（p<0.05）；经过发酵后样品的DPPH·清除能力均得到增强，乳酸肠球菌发酵红甜菜片抑制率最高达到55.32%；总抗氧化能力和ABTS+·清除能力在乳酸肠球菌和植物乳杆菌发酵的红甜菜片样品中分别显著提高，最大值分别为1.14 mM FeSO4/L和69.69%。这一研究为后续研究、开发红甜菜乳酸发酵制品提供了基础数据与理论依据。

In this study, fermentation of red beetroot pulp or slices was carried out using the Enterococcus lactis and Lactobacillus plantarum isolated from natural fermentation broth of red beetroot. The pH, total acid, number of lactic acid bacteria, total phenolic content, flavonoid content, total antioxidant capacity, and DPPH· and ABTS+·scavenging capacities were measured over the 48 h fermentation process. The results showed that the pH of the fermented red beet pulp and slices decreased significantly (p<0.05) (the lowest as 3.95). After fermentation, the total acid content increased (the highest as 16.78 g/kg). The maximum number of viable bacteria was 7.17 log(cfu/L) for the red beet pulp fermented with Enterococcus lactis. Compared with the unfermented samples, the greatest increase in the total phenol content was with fermented samples by Enterococcus lactis (755.30 mg/L; increased by 72.55%). The slices fermented by Lactobacillus plantarum had the highest flavonoid content as 0.92 mg/L (increased by 113.95%). The content of betacyanins in the pulp fermented by Lactobacillus plantarum decreased the fastest (decreased to 6.01 mg/100 mL; a decrease of 38.10 %). Opposite changes were found in the fermentation broth of red beetroot slices: the betalains content increased by 128.81% and 137.71%, respectively, with the betaxanthin in each sample increasing significantly in the first half of fermentation (p<0.05). The DPPH· scavenging capacities of the fermented samples were all enhanced, with the inhibition rate of the red beet slices fermented with Enterococcus lactis being the highest (55.32%). The total antioxidant capacity and ABTS+· scavenging capacity of the slices fermented with Enterococcus lactis or Lactobacillus plantarum increased significantly (maximum values were 1.14 mM FeSO4/L and 69.69%, respectively). This study provides basic data and theoretical basis for subsequent research and development of red beetroot lactic acid fermented products.

中央高校基本科研业务费专项项目（2572018BA07）