Exploration on Mechanism of Killing Molds in Corn by Microwave Treatment
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Abstract:
In order to discuss the presence of non-thermal effect during the process of killing molds in corn by microwave treatment, growth situation of Aspergillus funigatus, Aspergillus niger, Penicillium chrysogenum and Penicillium citrinum before and after microwave treatment were studied. The growth models of molds were established through the determination of mold growth amount, the absorbance values of protein and DNA, the permeability of electrolyte, and morphological changes of A. niger spore and situation of exudates were observed by atomic force microscope (AFM). Results showed that the lag phases of four kinds of molds became longer, population capacities lessened, and absorbance values of protein and DNA largened after microwave treatment, compared with water bath heating at the same temperature. It was indicated that more damages in molds occurred by microwave than water bath, suggesting non-thermal effects existed in the process of microwave sterilization. AFM examination showed that the morphology of A. niger spores’ before and after microwave treatment was quite different. The form of spores was full and the surface was relatively smooth before the microwave treatment, but they shrinked after the microwave treatment. More cellular content overflowed after microwave treatment, which proved that microwave treatment had damage effect on cell membrane of molds.
