University College Cork, Department of Food and Nutritional Science, Cork, Ireland.
Food Microbiol. 2011 May;28(3):547-53. doi: 10.1016/j.fm.2010.11.006. Epub 2010 Nov 19.
Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G*| compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity. The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.
水胶体可以改善面包的体积、质地和保质期。在发酵过程中由乳酸菌（LAB）产生的胞外多糖（EPS）可以替代水胶体。本研究旨在确定是否可以通过糖基转移酶从糖核苷酸合成的异多糖（HePS）在小麦和无麸质高粱酸面团中以有效水平产生。使用了产 HePS 的菌株乳杆菌 FUA3185、FUA3186 和布氏乳杆菌 FUA3154；当不存在蔗糖时不产生 EPS 的魏斯氏菌 10M 用作对照菌株。在 MRS 中，L. buchneri 的细胞悬浮液在低剪切速率下表现出最高的粘度。LAB 中负责 HePS 形成的糖基转移酶基因在高粱和小麦酸面团中表达。然而，只有布氏乳杆菌产生的 HePS 影响高粱酸面团的流变特性，而不影响小麦酸面团的流变特性。与对照相比，用 L. buchneri 发酵的高粱酸面团的 |G*| 较低，表明其抗变形能力降低。tan δ 的增加表明弹性降低。使用产生 HePS 的 LAB 扩展了 EPS 的多样性，并增加了用于烘焙的培养物的多样性。
