Enrichment of the low-fat yoghurt with oat β-glucan and EPS-producing Bifidobacterium bifidum improves its quality

摘要

The addition of β-glucan or EPS-producing bacteria is mainly used to improve the quality and the acceptability of low-fat yoghurt. The purpose of this study was to investigate the effect of adding β-glucan, EPS-producing Bifidobacterium bifidum, or both on physical properties, fermentation time, and organoleptic criteria of low-fat yoghurt, additionally to the viability of L. bulgaricus and B. bifidum. Two types of low-fat yoghurt (1.5% fat) were prepared, with the addition of standard oat β-glucan by 0.15% or without its addition. Each type of yoghurt mixture was inoculated with two kinds of starters: traditional and probiotic (B. bifidum) culture. The physicochemical properties, the count of viable bacterial starter culture, and the organoleptic evaluation for all yoghurt types were evaluated after storage 24 h at 4 °C. Moreover, the fermentation time was monitored. The incorporation of both β-glucan and EPS in yoghurt resulted in the highest viscosity (13.7 mPa.s) and WHC (55.94%), besides to the lowest syneresis (28.47%). The acidity and pH of the yoghurt samples were significantly affected (p > 0.05) by the β-glucan addition. The yoghurt type Bifidobacterium glucan had the shortest fermentation time (215 min), and the maximum viability of both B. bifidum (7.63 Log CFU g -1 ) and L. bulgaricus (7.50 Log CFU g -1 ). The β-glucan had a pronounced effect on the overall acceptability of yoghurt more than the EPS. In conclusion, enriching the low-fat yoghurt with oat β-glucan and EPS-producing B. bifidum is the highest effective method for improving the yoghurt’s quality and the viability of probiotics.