Screening and application of lactic acid bacteria and yeasts with l‐lactic acid‐producing and antioxidant capacity in traditional fermented rice acid

In the study, Lactobacillus paracasei H4‐11, Lactobacillus fermentum D1‐1, Lactobacillus casei H1‐8, Lactobacillus reuteri H2‐12, and Kluyveromyces marxianus L1‐1 were screened from traditional fermented rice acid based on several indicators: L‐lactic acid production capacity (13.46 ~ 19.69 g/kg), antioxidant capacity (DPPH clearance ability of 35.36 ~ 56.89%), and savory flavor indicators. Glutinous rice, quinoa, barley rice, and brown rice were selected to carry out rice acid fermentation. Different viable lactic acid bacteria and yeasts were screened, respectively, in the saccharification, acidification, alcoholization, and late acidification stages. Rice acid fermented with L. paracasei H4‐11 and K. marxianus L1‐1 in glutinous rice showed the high L‐lactic acid content (23.09 g/kg). The DPPH free radical scavenging ability in rice acid fermented with L. fermentum D1‐1 and L. paracasei H4‐11, respectively, reached 34.27% and 33.05% in 96 hr. Although quinoa rice acid had the highest L‐lactic acid content (33.74 g/kg) and the DPPH free radical scavenging ability (60.10%), it had the poor taste due to the high astringency intensity and bitter intensity. Rice acid fermented with both L. paracasei H4‐11 and K. marxianus L1‐1 in glutinous rice showed the highest savory flavor and had the lowest astringency and bitter. L. paracasei H4‐11 and K. marxianus L1‐1 were the potential strains for the fermentation of rice acid. These results promote the industrial development of Chinese rice acid. PRACTICAL APPLICATIONS: Rice acid as a functional nondairy fermented product is widely accepted by Chinese consumers. However, rice acid fermentation is still a traditional spontaneous process, which causes instability in its flavor and quality. Lactobacillus paracasei H4‐11 and Kluyveromyces marxianus L1‐1 screened in this study contributed to the improvements in the flavor and antioxidant capacity of rice acid. In addition, glutinous rice was confirmed as the suitable fermentation material of rice acid in the study.