Abstract
This study aimed to investigate the quality attributes of probiotic-fermented low-fat yoghurt enriched with barley beta-glucan (B beta G) during cold storage (5 degrees C) for 21 days. Low-fat yoghurt formulation was based on substitution of fat in the skim milk (SM) with B beta G (0.75 %, w/v). Four formulations of yoghurt were prepared. The control formulation (without the addition of B beta G) was produced from full cream bovine milk and fermented by yoghurt starter (YS). The first treatment (YS) was produced from SM without B beta G and fermented by YS. The second treatment was produced from SM with the addition of B beta G and fermented by YS (YSB beta G). The third treatment was produced from SM without B beta G and fermented by Bifidobacterium lactis Bb-12, and Lactobacillus acidophilus LA-5 (PY). The fourth treatment was produced from SM with the addition of 0.75% B beta G and fermented by Bifidobacterium lactis, and L. acidophilus (PYB beta G). All samples were evaluated for their chemical composition, microbiological properties, the viability of probiotic microorganisms, sensory quality attributes during the storage period. The results indicated that addition of B beta G improved the survival of probiotic bacteria and YS culture during storage period wherein the B beta G-enriched yoghurt had high viable count. There were no significant differences (p <= 0.05) between the treatments in the microbiological quality and chemical composition. On the other hand, the addition of B beta G improved the formation of flavor compounds in yoghurt. The substitution of fat with B beta G significantly (p <= 0.05) enhanced sensory attributes of yoghurt, wherein B beta G-enriched samples recorded high score and acceptability. The lactic bacteria count was 9x10(7) CFU mL(-1), and probiotic culture count was higher than 1x10(6) CFU mL(-1), which guarantees their effect and ability to survive in the digestive tract and spread in the intestine. It could be concluded that substitution of fat with B beta G is a sufficient delivery truck of probiotic culture and B beta G could be used safely in functional dairy products.