The impact of storage on the sensory, viscosity and chemical characteristics of yogurt fortified with oat β-glucan

Abstract

The feasibility of yogurt fortification with 0.3% oat β-glucan was examined. The results showed that 0.3% oat β-glucan yogurt has water-holding capacity. The acidity value and pH reached their maximum values at 7 d of storage, and no significant changes were observed after 7 d. All pH values ranged from 4.18 to 4.28, which are within the normal ranges for set-type yogurts. Interestingly, the viscosity values increased throughout storage. Significant differences were noted between the control yogurt and 0.3% oat β-glucan yogurt. The experimental sample had higher viscosity than the control yogurt, and the highest values were 58560 ± 2120 cp at 21 d for 0.3% oat β-glucan yogurt. The viability of probiotic bacteria in yogurts was checked. During the whole storage period, the content of probiotics decreased, which was only 0.63 ± 0.05×107 CFU/mL at 21 d. However, 0.3% oat β-glucan yogurt contained significantly more living probiotic bacteria compared to the control one, throughout the whole cold storage period. The viability of probiotic bacteria of 0.3% oat β-glucan yogurt at 14 d (3.18±0.2×107 CFU/mL) was only slightly lower than that of control yogurt at 1 d (3.45±0.3×107 CFU/mL). This fully demonstrates that the addition of 0.3% oat β-glucan has a protective effect on probiotics in yogurt, which will be beneficial for human health. The textural characteristics of yogurt were affected by the addition of 0.3% oat β-glucan, leading to decreased adhesiveness, but enhanced hardness and gumminess, throughout storage. All yogurts had average sensory scores of above 80, indicating a preference both for the control yogurt and 0.3% oat β-glucan yogurt throughout storage. The sensory results indicated that 0.3% oat β-glucan yogurt had the highest acceptability value of 86.49 at 21 d of storage, had a positive effect on the acceptability of the yogurt, independently of the storage time. Overall, yogurt containing 0.3% oat β-glucan could be an innovative healthy dairy product.