Effect of formulation and processing conditions on the rheological and sensory properties of rice milk.

摘要

This study was conducted to assess the effect of processing conditions and ingredient functionality on quality attributes of rice milk. Since rice contains a limited amount of proteins, whey proteins were added to improve nutritional properties. Various rice fractions from long and medium grain rice were turned into slurry by the wet milling method. To this slurry, rice bran oil, sugar and various amounts of whey proteins (0 to 6%) were added. After blending, filtering, and homogenization, the rice solution was given a preheating treatment to enhance its functional properties and shelf life. A detailed study of rheological and sensory properties was carried out to evaluate appropriate processing conditions, rice sources and whey protein levels to produce an optimum product. Finally, a storage study was conducted to determine the effect of storage on the physical and chemical properties of rice-whey milk. The results showed that broken rice has similar flow behavior as polished rice and thus can be used as an ingredient in rice milk preparation. Rice milk from long and medium grain rice and rice milk from white and brown from the same varieties showed different flow behavior patterns. The preheating temperature greatly influenced the flow behavior of rice milk. When rice milk was preheated to the gelatinization temperature of the rice, it showed a Newtonian behavior. The addition of whey proteins increased the consistency coefficient and decreased the flow behavior index. When rice milk was stored at 4°C for 16 days the consistency coefficient was lower compared to that of freshly processed rice milk. The flow behavior index was influenced by the rice variety, milling fraction, whey protein concentration and storage duration. However, there was no distinct pattern in flow behavior changes during storage. The addition of whey proteins did not seem to affect the sensory attributes of rice milk and tended to improve viscosity. Therefore, formulation of rice milk with added whey proteins could expand the consumer appeal for rice milk. The characterization of rice milk through rheological properties provided much needed information for process engineering calculations, determining ingredient functionality, and the quality control of existing rice milk products.