Stabilizing effect of Leuconostoc mesenteroides Lm10 produced dextran in situ on stirred soy yogurt: Structure-function relationship.

Stirred soy yogurt as a dairy alternative is widely accepted among consumers, but its poor stability has been an urgent problem. We found that Leuconostoc mesenteroides Lm10 produced dextran reduced water mobility and improved the water holding capacity of stirred soy yogurt, especially with over 4 % sucrose added which could completely prevent whey separation. With the increase of dextran content, the particle size of stirred soy yogurt was significantly decreased, accompanied by the improvement of viscoelastic behaviors and resistance to deformation. Moreover, dextran had a stronger ability to maintain the stability of stirred soy yogurt in comparison with gelatin, xanthan and carrageenan during cold storage. The structure-function attributes of this dextran were also revealed. Dextransucrase Gtf1674 was responsible for synthesizing dextran during soy yogurt fermentation. The produced dextran was mainly composed of α-1,6 glycosidic linkages with a low-branched degree and high molecular weight. After stirring, the dextran entangled with soy protein and formed small aggregates with a dense gel structure and small pores, causing them prone to binding with water and reducing the syneresis. This study suggested the benefits of dextran produced by Leuc. mesenteroides Lm10 in stirred soy yogurt, and facilitated developing the "clean label" plant-derived products.