关键词: 纯种发酵, 淀粉, 分子结构, 老化

Abstract: In this study, we examined the effects of fermentation by pure cultures of Lactobacillus plantarum, Pediococcus pentosaceus, Enterococcus faecium, Saccharomyces cerevisiae and Bacillus, which play an important role in affecting the retrogradation properties of naturally fermented starch, on the molecular structure and retrogradation characteristics of millet starch with the aim of providing a theoretical basis and data support for elucidating the mechanism by which natural fermentation and pure culture fermentation improve the retrogradation properties of millet starch, and new ways of developing fermented millet products. Millet starch was extracted from fermented millet with 0.2 g/100 mL NaOH and evaluated for granular characteristics, functional groups, molecular mass and, pasting and retrogradation properties. The results obtained were as follows. Fermentation did not changed the cross polarization characteristics of starch. The surface of millet starch granules fermented by Lactobacillus plantarum, Pediococcus pentosaceus and Enterococcus faecium was eroded, but the surface of starch granules after fermentation by Saccharomyces cerevisiae and Bacillus was eroded more seriously, with more deeper channels. The fermentation by Saccharomyces cerevisiae and Bacillus did not change the peak positions in the functional region, but reduced the intensity of the characteristic peaks. The fingerprint region of millet starch fermented by Lactobacillus plantarum, Pediococcus pentosaceus and Enterococcus faecium partially disappeared, The weight average and number average molecular masses in regions Ⅰ and Ⅱ were decreased after fermentation by Lactobacillus plantarum. In region Ⅰ, the weight average molecular mass after fermentation by Pediococcus pentosaceus, Enterococcus faecium and Saccharomyces cerevisiae was increased, and the average molecular weight was decreased, while in region Ⅱ, the weight average and number average molecular masses were both decreased. After fermentation by Bacillus, the number average molecular mass in region Ⅰ was slightly increased, but the weight average molecular weight was slightly decreased; both the weight average and number average molecular weight in region Ⅱ were decreased. The gelatinization temperature, final viscosity and retrogradation value were decreased, but the enthalpy was increased after fermentation by Lactobacillus plantarum, Pediococcus pentosaceus and Enterococcus faecium. The gelatinization temperature and retrogradation value were decreased, the final viscosity and enthalpy were increased after fermentation by Saccharomyces cerevisiae. In conclusion, fermentation could change the molecular structure of starch, branched chain starch and amylose, and improve the short-term anti-retrogradation performance.

Key words: pure culture fermentation, starch, molecular structure, retrogradation