Application of Cinnamaldehyde Microcapsules in Anti-fungal Preservation of Purple Rice

In order to compare the antimicrobial and fungicidal properties of common natural plant extracts against dominant molds in purple rice and to investigate their application in purple rice storage, this study isolated and purified molds in moldy purple rice, and identified the dominant molds by microscopic examination and molecular biology. On this basis, the inhibitory properties of six natural plant extracts, citral, cinnamaldehyde, p-anisaldehyde, tea polyphenols, thymol and eugenol, were investigated against dominant molds of purple rice. The natural plant extracts with the best bacteriostatic properties were selected and their minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) against dominant molds were determined. Then the best preparation process of cinnamaldehyde microcapsules was optimized by orthogonal test, and the microcapsules were packed in non-woven bags after drying and applied in the accelerated storage test of purple rice at 35 ℃. Finally, moisture, mold content, odor, and color difference were used as indicators of the freshness of purple rice to evaluate the preservation effect of cinnamaldehyde microcapsules on purple rice. The results showed that the dominant molds of moldy purple rice were Aspergillus versicolor, Aspergillus chevalieri, Cladosporium tenuissimum, Aspergillus candidus and Rhizomucor pusillus, cinnamaldehyde had the best inhibitory effect on the above molds, and its MIC was measured as 2, 1, 1, 2, 1 mg/mL, and MBC was measured as 4, 8, 4, 16, 4 mg/mL, respectively. The optimal preparation process of cinnamaldehyde microcapsules was as follows: The concentration of sodium alginate was 3%, the concentration of calcium chloride was 1%, the wall-core ratio was 12:1, and the distance between the liquid surface of the pelleting was 25 cm, and the encapsulation rate of the cinnamaldehyde microcapsules produced by the process was 96.67%, and the oil-carrying rate was 61.27%. The cinnamaldehyde microcapsules made the freshness indexes of purple rice better than the blank control group, indicating that the prepared cinnamaldehyde microcapsules have a positive effect on the preservation of purple rice.