Changes in lipids and in sensory attributes on storage of rice milled to different degrees

Summary Under-milled and well-milled rice samples were compared, before and after storage, by chemical and sensory tests. Surface lipids, non-starch lipids, and starch lipids were quantified, and free fatty acids, total carbonyls and hexanal contents of the surface lipids were determined as measures of lipid hydrolysis and oxidation during storage for up to 9 months at -20 and 30°C. Descriptive sensory analysis of cooked rice by a trained panel was used to compare odour, taste and mouth-feel of both stored and freshly milled samples. Triangle and preference tests by an untrained panel were used to establish whether perceptible differences were caused by the degree of milling or the storage conditions. Similar changes, both chemical and sensory, occurred in the under-milled and well-milled rice during storage but these were more pronounced in the under-milled rice, leading to a product of poorer storage stability and reduced preference.