Exopolysaccharide-producing mesophilic lactic cultures for preparation of fat-free Dahi – an Indian fermented milk

Abstract

Forty seven exopolysaccharide (EPS) producing mesophilic lactic acid bacteria have been isolated from Dahi and raw milk and selected cultures were evaluated for their influence on rheological and sensory properties of fat-free Dahi. Two isolates namely B-6 and KT-24 that showed promising technological attributes were identified as Lc. lactis subsp. lactis strains. B-6 produced 184+/-2 mg/l EPS in deproteinized whey medium compared with 193+/-1 mg/l by KT-24. EPS produced by B-6 was a heteropolysaccharide (consisting of glucose and mannose, 1:7 x 4) with molecular weight of 3.0x104 Da whereas KT-24 EPS was a homopolysaccharide (rhamnose) having molecular weight of 4.5x104 Da. Both EPS producing cultures showed significant changes in rheological and sensory properties of fat-free Dahi. Dahi prepared by these cultures was more viscous, adhesive, sticky, showed lower susceptibility to whey separation, and received higher sensory scores than Dahi prepared with non-EPS producing culture.

Exopolysaccharides producing Lactobacillus fermentum strain for enhancing rheological and sensory attributes of low-fat dahi

“…Purified EPS was hydrolyzed with HCl by adding 500 μl EPS fraction and an equal volume of 2 M HCl in a glass ampoule which was then sealed and heated at 100°C for 4 h. Hydrolyzed material was neutralized with 2 M NaOH (500 μl) (Behare et al 2009a). Determination of monosaccharide composition was performed by HPCL with sugar Pak I (300×6.5 mm) column and a refractive index detector using 100 % water (HPLC grade as mobile phase (Behare et al 2009a).…”

“…Determination of monosaccharide composition was performed by HPCL with sugar Pak I (300×6.5 mm) column and a refractive index detector using 100 % water (HPLC grade as mobile phase (Behare et al 2009a).…”

“…Whey separation was determined by the method of Wacher-Rodarte et al (1993) and Behare et al (2009a). Whey separation was expressed as weight (g) of expelled whey per 100 g dahi.…”

“…Viscosity was measured by arbitrary procedure using Contraves Rheomat 108 E/R Coaxial Cylinder Viscometer (Metler-Toledo, Switzerland) as per the method described by Behare et al (2009a). Texture Profile Analysis (TPA) was carried out by the method described by Behare et al (2009a) and Kumar and Mishra (2003).…”

“…(Behare et al 2009a(Behare et al , b, 2010. Besides acting as biothickening agents, some EPS produced by LAB have showed beneficial effects on human health (Chabot et al 2001).…”