植物乳杆菌ST-III发酵苦荞面团中蛋白质降解规律的研究

苦荞蛋白作为苦荞中最主要的生物活性物质以及重要的营养成分之一,具有生物价高与氨基酸比例均衡等优点。但由于苦荞蛋白的组成中面筋蛋白含量较少且本身难以被吸收等方面的问题,其加工利用一直受到较大的限制。面团发酵技术作为一种能够提升面团加工品质以及最终产品营养价值的微生物发酵技术,能够提高谷物中蛋白质的利用率。本文选用植物乳杆菌ST-III(Lactobacillus plantarum ST-III)应用于苦荞面团发酵,通过比较苦荞发酵面团(Buckwheat Sourdough,简称BS)、小麦发酵面团(Wheat Sourdough,简称WS)和混合发酵面团(Wheat-Buckwheat Sourdough,简称WBS)发酵过程中变化发现：植物乳杆菌ST-III在BS发酵过程中菌落密度始终较大且显著高于WS和WBS中植物乳杆菌ST-III的菌落密度(p＜0.05),发酵24 h后可达到13.62 logCFU/g酸面团,同时,BS的pH为6.58,接近植物乳杆菌ST-III的最适pH,总酸含量最高达到24.39 mL,其中,乳酸以及乙酸含量分别是WS 与WBS的1.61-1.75倍以及1.06-1.15倍。此外,通过对三种面团发酵过程中总蛋白、清蛋白、醇溶蛋白、谷蛋白以及游离氨基酸含量的测定,并利用SDS-PAGE凝胶电泳发现,植物乳杆菌ST-III在发酵过程中对三种酸面团中总蛋白及其各组分的降解作用有显著差异(p＜0.05),其中,植物乳杆菌ST-III发酵对BS中苦荞蛋白的降解效果最为明显,且游离氨基酸含量随着发酵的进行呈上升趋势。综上可知,利用植物乳杆菌ST-III发酵苦荞酸面团不仅能够改善苦荞中面筋蛋白含量不足导致的加工品质较差的问题,而且提升了苦荞中蛋白质的利用率。

Study on the Law of Protein Degradation in Tartary Sourdough Fermented by Lactic Acid Bacteria

Tartary buckwheat protein, as the most important biologically active substance and one of the important nutrients in tartary buckwheat, has the advantages of high biological value and balanced amino acid ratio. However, due to the low content of gluten protein in the composition of tartary buckwheat protein and the difficulty of being absorbed by itself, its processing and utilization have been greatly restricted. Sourdough fermentation technology is a microbial fermentation technology that can improve the quality of dough processing and the nutritional value of the final product. In particular, the lactic acid bacteria in its system can degrade macromolecular proteins in grains into small peptide chains and Free amino acids, thereby improving the utilization of protein in grains. In this paper, Lactobacillus plantarum ST-III (Lactobacillus plantarum ST-III) is used in fermented tartary buckwheat sourdough. By comparing tartary buckwheat sourdough (Buckwheat Sourdough, BS), wheat fermented sourdough (Wheat Sourdough, WS) During the fermentation of Wheat-Buckwheat Sourdough (WBS), it was found that the buckwheat protein and amino acid changes during the fermentation process: The colony density of Lactobacillus plantarum ST-III was always larger during the BS fermentation process and was significantly higher than that of WS and WBS plants. The colony density of Lactobacillus ST-III can reach 13.62 logCFU/g sourdough after 24 hours of fermentation. At the same time, the pH of BS is 6.58, which is close to the optimal pH of Lactobacillus plantarum ST-III, and the total acidity of BS is 24 hours after fermentation. The content reaches 24.39 mL. Among them, the content of lactic acid and acetic acid is the largest, which are 1.61-1.75 times and 1.06-1.15 times of WS and WBS respectively. It can be seen that the weak acid environment of BS is not only suitable for the growth and reproduction of Lactobacillus plantarum ST-III, but also It can further increase the output of its organic acids, thereby promoting its degradation of proteins. In addition, through the determination of the total protein, albumin, gliadin, gluten and free amino acid content during the fermentation of the three types of sourdough dough, and the use of SDS-PAGE gel electrophoresis and scanning electron microscopy, it was found that Lactobacillus plantarum ST-III was There are significant differences in the degradation of the total protein and its components in the three types of sourdough during the fermentation process (p<0.05). Among them, the fermentation of Lactobacillus plantarum ST-III has the most obvious degradation effect on the tartary buckwheat protein in BS. The free amino acid content showed an upward trend as the fermentation progressed. In summary, using Lactobacillus plantarum ST-III to ferment tartary buckwheat sourdough can not only improve the problem of poor processing quality caused by insufficient gluten protein content in tartary buckwheat, but also improve the utilization of protein in tartary buckwheat.