Effect of Particle Size of Oat (Avena sativa) Flakes on Physicochemical and Sensory Properties of Oat Incorporated Drinking Yoghurt
Hansani De Silva, Geethi Pamunuwa and Amani Wijesinghe
Abstract
Background: Consumption of oats (Avena sativa) has increased steeply over the last few years due to the multiple health benefits shown by its constituents, including dietary fibre. Accordingly, numerous functional foods have been formulated incorporating oats. The aim of this study was to determine the optimum particle size of oat flakes for the development of oat incorporated drinking yoghurt.
Methods: Drinking yoghurt was formulated incorporating oat flakes of particle sizes 850-425 μm, 425-180 μm and <180 μm. Physicochemical parameters of the formulated drinking yoghurts, including pH, Titratable Acidity (TA), Total Soluble Solids (TSS), degree of syneresis and firmness were determined for 21 days. The sample that showed the best sensory attributes and physicochemical properties was analysed for proximate composition and microbial safety.
Results: The sensory attributes of the drinking yoghurts with oat flakes of three different particle sizes were not significantly different (P>0.05). The particle size of oat flakes affected the physicochemical properties of drinking yoghurts. In fact, the yoghurt with oat flakes of the smallest size showed the highest titratable acidity, TSS and firmness in the drinking yoghurt (P≤0.05). The variation of the physicochemical properties of the yoghurts with time followed a similar pattern. In fact, the pH decreased, TA increased, while TSS decreased with time (P≤0.05). The selected drinking yoghurt, which was prepared incorporating oat flakes of size range 850-425 μm and 300 ppm of potassium sorbate, showed a shelf life of 14 days at 4 °C. It exhibited similar sensory attributes other than taste to a popular drinking yoghurt from the market.
Conclusions: Drinking yoghurt incorporated with oat flakes of 850-425 μm size range showed a better taste and nutritional profile, than regular yoghurt.
Keywords: Drinking Yoghurt, Oat Flakes, Particle Size, Physicochemical Properties, Sensory Properties