标题：Changes in the physicochemical and microbiological properties of probiotic-fermented low-fat yoghurt enriched with barley β-glucan during cold storage
摘要：This study aimed to investigate the quality attributes of probiotic-fermented low-fat yoghurt enriched with barley β-glucan (BβG) during cold storage (5 °C) for 21 days. Low-fat yoghurt formulation was based on substitution of fat in the skim milk (SM) with BβG (0.75 %, w/v). Four formulations of yoghurt were prepared. The control formulation (without the addition of BβG) was produced from full cream bovine milk and fermented by yoghurt starter (YS). The first treatment (YS) was produced from SM without BβG and fermented by YS. The second treatment was produced from SM with the addition of BβG and fermented by YS (YSBβG). The third treatment was produced from SM without BβG 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% BβG and fermented by Bifidobacterium lactis, and L. acidophilus (PYBβG). 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 BβG improved the survival of probiotic bacteria and YS culture during storage period wherein the BβG-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 BβG improved the formation of flavor compounds in yoghurt. The substitution of fat with BβG significantly (p≤0.05) enhanced sensory attributes of yoghurt, wherein BβG-enriched samples recorded high score and acceptability. The lactic bacteria count was 9×107 CFU mL–1, and probiotic culture count was higher than 1×106 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 BβG is a sufficient delivery truck of probiotic culture and BβG could be used safely in functional dairy products.
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