Improvement in storage stability of lightly milled rice using superheated steam processing

• Superheated steam (SS) processing extended shelf-life of lightly milled rice (RLMR).
• SS processing suppressed lipids deterioration of RLMR during storage.
• SS processing preserved the grain appearance of RLMR during storage.
• SS processing retarded the changes in pasting properties of RLMR during storage.
• Micro-mechanical behavior of RLMR inevitably altered during storage.

Superheated steam (SS) processing was used to inactivate peroxidase in lightly milled rice (RLMR) in order to prolong its shelf-life. The effect of the SS processing on changes in physicochemical characteristics of RLMR during six months of storage were assessed. SS processing could effectively inhibit lipid deterioration in RLMR by suppressing the oxidation of unsaturated fatty acids and by reducing the acid value, peroxide value and carbonyl value. The changes of pasting properties, including peak viscosity, trough viscosity, final viscosity, setback and pasting temperature were also retarded by SS processing. The grain appearance was well preserved whereas the micro-mechanical behavior of starchy endosperm was inevitably changed (intercellular cleavage shifted to intracellular cleavage). The utilization of vacuum packaging did not evidently improve the effectiveness of SS processing. The SS processing alone was more effective than low temperature (4 °C) storage for extending the shelf-life of RLMR.