Functional enhancement of yoghurt through incorporation of glucan exopolysaccharide from Enterococcus hirae OL616073 of food origin

Microbial exopolysaccharides (EPS) are extracellular polymeric substances synthesized by bacteria, fungi or algae which are now one of the important food ingredients. In this study, glucan EPS was isolated from lactic acid bacteria (LAB) of fermented food origin and was incorporated in yoghurt to enhance its techno-functional attributes and rheological properties. Glucan EPS concentration at 1% showed significant improvement in syneresis, wheying off, water-holding capacity, and sensorial properties of yoghurt. The water holding capacity (WHC) increased from 47% to about 63% while syneresis decreased from 52% to nearly 30%. Rheological features such as viscosity, storage modulus, loss modulus, and firmness were significantly higher for 1% EPS containing yoghurt (1% ECY) than that of the control. The average particle size of 1% ECY was increased from 2.35 µm to 3.46 µm. The microstructure of EPS containing yoghurt was studied by scanning electron microscopy and confocal laser scanning microscopy. EPS supports the growth of probiotic microflora of yoghurt, which was revealed by analyzing the microbial count of yoghurt. The antioxidant activity as 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (mg Trolox/100 g sample) and reducing power assay (mg ascorbic acid/100 g sample) for 1% ECY and control yoghurt were found to be 27.9 (mg Trolox/100 g sample), 6.44 (mg Trolox/100 g sample) and 0.25 (mg ascorbic acid/100 g sample), 0.19 (mg ascorbic acid/100 g sample), respectively. Significant enhancement of these bio-functional attributes of EPS containing yoghurt makes the glucan EPS a suitable hydrocolloid to develop various functional foods.