Characterization of differences between microwave and traditional thermal sterilization to prevent fungal spoilage during storage of high moisture paddy rice

Background and objectives Characteristic difference between microwave (MW; 2.45 GHz, 1.5 W/g) and traditional thermal (TT; water bath, 100 degrees C) sterilization on representative fungi (Aspergillus candidus,Aspergillus glaucus,Penicillium chrysogenum,Alternaria alternata, andFusarium nivale) on high-moisture paddy rice was evaluated by observing heat absorption of rice surface, fungal mortality, growth, and cell permeation. Findings Using MW (2.45 GHz, 1.5 W/g) can inhibit the growth of fungi, such asAspergillus candidus. Under our experimental conditions, MW radiation was effective for safe storage of high-moisture rice with fungal mortality of 95%. Fungal dehydrogenase activities after MW treatment were nearly 50% lower than fungal dehydrogenase activities after TT. Both MW and TT at the same temperature (60 degrees C) can inhibit the growth of fungal spores. However, MW had better inhibitory effect, which is conducive to the safe storage of high-moisture paddy rice. Conclusions Microwave and TT sterilization destroy fungal cell, causing substantial cell leakage and death. MW is more destructive to organisms on high-moisture paddy rice than TT, which may be due to the nonthermal effects of MW. Significance and novelty Compared with TT, MW has better sterilization and could prevent fungal contamination in high-moisture paddy rice storage and other cereals.