Application of Trehalose Dihydrate for the Improvement of Cooked Rice Quality and Extension of Shelf Life

Cooking methods, such as steaming, may cause quality issues in cooked rice during storage due to the retrogradation of gelatinised starch and other related structural changes. This study is aimed at enhancing the shelf life of cooked rice blocks (nigiri) by applying trehalose dihydrate, thereby improving the quality and palatability of the samples over their shelf life without compromising food safety. Two samples (4TH15, containing 15% trehalose and 5% sucrose, and a control [C4]) were prepared after the initial sensory (preference) testing, and they were analysed for physicochemical (pH, water activity and textural properties) and nutritional properties. Microbial analysis involved testing for yeast and moulds, total viable count (TVC) and challenge testing for Bacillus cereus and Listeria monocytogenes . Sensory analysis to determine shelf life extension included triangle testing. The application of trehalose dihydrate at 15% and sucrose at 5% improved the perceived quality of cooked rice, with a notably higher preference over a 7‐day testing period. No ascertainable difference was found when comparing 2‐day older trehalose‐containing samples to control samples over shelf life, and this suggested that quality degradation was inhibited. This was further demonstrated through texture analysis of relevant quality parameters, with slower increases in hardness and firmness and improved retention of stickiness during shelf life. No yeast and mould growth was detected during shelf life testing, with TVC levels remaining insufficient to yield perceivable spoilage. The growth of B. cereus and L. monocytogenes was not supported. Therefore, trehalose was suitable for improving the shelf life and quality of cooked‐acidified rice without posing a detriment to food safety.