Surber Georg, Mende Susann, Jaros Doris, Rohm Harald
Institute of Natural Materials Technology, Technische Universität Dresden, 01062 Dresden, Germany.
Foods. 2019 Apr 30;8(5):146. doi: 10.3390/foods8050146.
In situ produced extracellular polysaccharides (EPS) from lactic acid bacteria are generally known to affect the texture of fermented dairy products; however, the interplay between EPS and product properties is still poorly understood. The aim of this study was to establish a relationship between concentration and properties of EPS, and gel formation of milk analysed by noninvasive Multispeckle Diffusing Wave Spectroscopy. Twenty strains were classified with respect to EPS concentration (8-126 mg GE/kg) and ropiness (thread length: 15-80 mm). Five groups identified by cluster analysis demonstrate the high strain-to-strain variability even within one species of lactic acid bacteria. Results from acidification and gelation experiments averaged per cluster indicate that fermentation time and gel stiffness is higher for strains that produce ropy EPS. A further increase in gel stiffness was detected for strains that also produced cell-bound EPS, which underlines the importance of both ropy and cell-bound EPS for improving acid gel properties. The results may be helpful for a proper selection of EPS-producing starter cultures.
一般认为，乳酸菌原位产生的胞外多糖（EPS）会影响发酵乳制品的质地；然而，EPS与产品特性之间的相互作用仍未得到充分理解。本研究的目的是通过无创多散斑扩散波谱分析建立EPS浓度与特性之间的关系，以及牛奶的凝胶形成关系。根据EPS浓度（8 - 126 mg GE/kg）和黏稠度（线长：15 - 80 mm）对20株菌株进行了分类。聚类分析确定的五组结果表明，即使在一种乳酸菌内，菌株间的变异性也很高。每组酸化和凝胶化实验的平均结果表明，产生黏稠EPS的菌株发酵时间和凝胶硬度更高。对于还产生细胞结合EPS的菌株，检测到凝胶硬度进一步增加，这突出了黏稠EPS和细胞结合EPS对改善酸性凝胶特性的重要性。这些结果可能有助于正确选择产生EPS的发酵剂培养物。
