Accelerated aging of rice by controlled microwave treatment. (1st September 2020) - Zhong, Yejun
Highlights: The aging process of rice is accelerated by controlled microwave treatment (MW). The mechanism by which MW accelerates rice aging is illustrated. MW modifies technological properties of rice similar to the natural aging process. The technological properties are modified due to restricted swelling of rice flour. The swelling is restricted by enhanced protein gel network and cell wall strength. Abstract: To obtain the desired technological properties (pasting, texture, and rheology) of naturally aged rice (AR), the aging process of freshly harvested rice was accelerated by controlled microwave treatment at 540 W for 1–3 min. Similar to AR, the rice microwave treated for 2 min showed increased pasting viscosities (peak, trough, breakdown, final, and setback) and pasting temperature, enhanced gel hardness and strength, and reduced gel adhesiveness. The mechanism by which microwaves accelerated rice aging was illustrated. Microwave treatment promoted the formation of protein disulfide bonds and the release of free phenolic acids, which enhanced protein gel network and cell wall strength. This phenomenon inhibited the swelling of starch granules and consequently modified the technological properties of rice. The crystalline structure and fatty acid content of rice flour was uninvolved in the mechanism, but the microwave–induced micromechanical change (intercellular cleavage to intracellular cleavage) of rice endosperm may be involved.