Study on the Synthetic Capsaicin to Fight Pests and in Rice Storage

2022-12-21 18:15

　　Synthetic capsaicin is an important functional ingredient of plants. Based on its strong spicy effect, there have been many studies on it as a condiment and medicine. This study has not been reported yet. Food safety problems are not only caused by pesticide pollution during the production process, but also by chemical pollution during post-production storage. Chemical drugs are often used to control insects, molds and rats, leading to the increasingly prominent 3R problem. At present, the research on environmentally friendly biopesticides is in the ascendant. In-depth research on the relationship between capsaicin and pests can explore new ideas and methods for safe grain storage.

　　This study focused on my country's two major resources, rice and synthetic capsaicin, and explored the dose-response relationship of capsaicin on a variety of pests, as well as the preparation process of synthetic capsaicin as the main component of grain storage protectants and its acceptability to grain crops. Rice storage research. According to the relevant research conclusions, rice storage experiments were carried out to provide a scientific basis for the use of synthetic capsaicin to control rice storage pests and achieve "one dose for multiple preventions", which has important theoretical and practical significance. The main conclusions of this study are as follows:

　　1. Repellent effect of synthetic capsaicin on stored-grain rodents The repellent effect of capsaicin was evaluated by using different capsaicin concentrations (0.1%, 0.2%, 0.4%) and different application methods (immersion, spraying, and smearing), rice as bait, and four common stored-grain rodent species, with bites and food damage as evaluation indicators.

　　2. Inhibitory effect of synthetic capsaicin on microorganisms on the surface of rice. Through separation and culture, the total number of microbial colonies on the surface of stored rice grains was measured to be 4.9×103cfu/g, and the main microorganisms were Aspergillus flavus and Aspergillus niger. Within the normal storage temperature range, capsaicin can maintain good antibacterial activity. When the concentration of capsaicin is 2.0 mg/mL, it has obvious antibacterial effect on Aspergillus niger and Aspergillus flavus. Amplification tests show that the effective antibacterial effect of 2.0 mg/mL capsaicin on the tested strains is from large to small: Staphylococcus aureus, Salmonella, Bacillus subtilis, Escherichia coli, Aspergillus niger, and Mucor.

　　3. Optimization of the preparation process of synthetic capsaicin rice storage protectant Through single factor and orthogonal experiments, the optimal process for extracting capsaicin by ultrasonic assisted method with ethanol as extraction solvent was determined as follows: ultrasonic time 50rmin, crushing particle size 80 mesh, extraction temperature 50℃, solid-liquid ratio 1:20. Under these conditions, 19.8 mg of capsaicin can be extracted per gram of dry chili powder, and the one-time extraction rate of capsaicin can reach 86.32%. The capsaicin microcapsule powder obtained under these conditions was observed by scanning electron microscopy (SEM), and its shape was mostly irregular spherical, with a particle size of about 100μm. The sensory acceptance of capsaicin was improved after microencapsulation.

　　4. Evaluation of the acceptability of synthetic capsaicin for rice storage This study comprehensively considered the safety, solubility, acceptability, stability and cost of use of capsaicin storage grain preparations, and determined ethanol as a capsaicin rice storage protectant. Sensory evaluation tests were conducted on capsaicin storage preparations of different concentrations and different application methods, and the results were all within the sensory acceptable range; the residue of rice directly treated with different amounts of capsaicin after 90 days of storage, the capsaicin residue in brown rice was less than 10% of the added amount. According to the maximum theoretical application dose determined in this study, 8 g/t rice was treated. The residue is completely acceptable.

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