Controlling fungal growth and quality deterioration in germ-remaining rice using silkworm pupa chitosan

Abstract Germ-remaining rice is prized for its high nutritional density, but its intense metabolic activity accelerates quality deterioration and severely curtails shelf life. Silkworm pupa chitosan has excellent antioxidant and antimicrobial activities and is widely used in food preservation. To mitigate germ-remaining rice metabolism and delay its quality decline, this study evaluated the antioxidant activity of silkworm pupa chitosan at different concentrations in acetic acid and its inhibitory effects against Aspergillus flavus and Aspergillus niger infested in rice. Silkworm pupa chitosan was applied for germ-remaining rice preservation. The results demonstrated that silkworm pupa chitosan at a concentration of 8 mg/mL exhibited the highest antioxidant activity. It significantly inhibits the growth of molds both in vitro and on germ-remaining rice. Silkworm-pupa chitosan suppressed the transition of bound to free water in germ-remaining rice while facilitating the reverse conversion. Silkworm pupa chitosan significantly enhanced the activities of α-amylase and β-amylase, leading to a controlled reduction in starch content. It significantly delayed fatty acid accumulation, malondialdehyde production, and protein degradation. These combined effects effectively mitigated undesirable texture changes. Silkworm pupal chitosan demonstrates strong potential as a natural preservative for germ-remaining rice, offering a practical strategy to prolong its shelf life and commercial value.