Research On Preventing Biohazard By Capsaicin And Its Utilization In Green Storage Of Rice

Capsaicin is a kind of important plant functional component. In more studies capsaicin is used as condiment and drug based on its strong hot effect. But research on preventing biohazard of capsaicin about the quantity-efficiency relation and its utilization in green storage of rice has seldom been reported. Grain safety problems, not only exist in production for pesticide contamination, also in postharvest storage for chemical pollution. Being suffered from harmful biohazard such as pests, mould, rats etc., grain was caused quantity loss and quality deterioration in the process of storage. While using chemical pesticides for prevention, it caused the 3 R (Resistance, Residue, Resurgence) problem increasingly. At present, it is prevalent to carry out environment friendly biological pesticide research. Further study of the relationship between capsaicin and harmful biohazard will explore new ideas and methods for safety grain storage.Rice and chilli are two kinds of rich resources in our country. This study discussed the quantity-efficiency relation of capsaicin preventing various harmful biohazard. Preparation technology of grain storage protective agent was then researched, in which capsaicin provided main effect. Its acceptability evaluation in rice storage test was also conducted. The study provided scientific basis for using capsaicin to control pests, repel rats, inhibit bacteria, and last realized a dose for more usage. Therefore it had important theoretical and practical significance in rice storage control. The main conclusions were as follows.1 Repelling effect on rats in grain storage of capsaicinDifferent capsaicin concentration (0.1%、0.2%、0.4%), different treatment methods (soaking, spraying and daubing), rice as bait, four kinds of common rats in rice storage, biting and rice damage as evaluation indicator were used to evaluate the repelling rat effect of capsaicin. The results found that woven fabric bag pieces were treated over 0.2% capsaicin solution, then placed in rat cages, had better repelling effect on four rats, with no biting damage in 480 h. Using 0.2% capsaicin solution by soaking, spraying and daubing 3 treatment methods on woven fabric bags (theory dosage 85mg/m2), daubing treatment effect was the best, which reached more than 350 d protection period. While daubing, adding directly and spraying 3 treatment methods on PVC grain storage, the front two methods had better preventing rats effect in rice storage, which reached over 210 d protection period. Combining prevention rat effect in real warehouse with sense acceptability evaluation,0.2% capsaicin concentration as rat repelling agent was determined. 2 Repelling and touch killing effect of capsaicin on pests in rice storageFilter paper absorption capsaicin solution as method,4 kinds of rice storage pests as test objects, repelling rate, death rate, resisting feed, growth, reproduction and cargo rice damage by pests as inspecting indicators, which were used to studied the preventing effect on pests of capsaicin. The result showed that when capsaicin concentration was over 2.0%, the repelling effect of was relative obvious to Sitophilus zeamais, Tribolium castaneum, Liposcelis bostrychophila, and inferior to Rhizopertha dominica. But the touch killing effect was not obvious to four kinds of pests in rice storage. According to the ratio of capsaicin to cargo rice 4g/kg and 2g/kg, Sitophilus zeamais and Tribolium castaneum appeared distinctly refusing feed effect. The damage rate of cargo rice in 30 days caused by Sitophilus zeamais was only 26.4% and 35.4% of blank control, similarly Tribolium castaneum caused damage rate only 24.8% and 30.6% of blank control. Reproduction effect of Sitophilus zeamais and Tribolium castaneum were observed according to adding different capsaicin quantity in cargo rice within 40 days. The reproduction number caused by Sitophilus zeamais and Tribolium castaneum was only 9.23% and 26.1% of blank control, according to 0.05g capsaicin per 100g cargo rice. When adding capsaicin 0.2g per 100g cargo rice, Sitophilus zeamais lived only 1 and Tribolium castaneum zero survived. The result showed that capsaicin had obvious inhibition effect on tested pests. The higher content of capsaicin the bigger the inhibition effect. Finally it accelerated death of tested pests.The study determined 2% capsaicin content in grain storage protective agent. In expand pilot test, using 2% capsaicin powder 40kg on the surface layer grain in shallowly along depot could control occurrence and harm of booklice. Compared with 10% booklice emulsifier,2% capsaicin powder 20kg treated on packaged grain storehouse had better effect and could reduce 50% booklice density.3 Inhibition effect of capsaicin on microorganism in grain storageTotal colonies were 4.9×103 cfu/g from storage rice surface by isolation and culture. The main grown microorganism was Aspergillus flavus and Aspergillus niger.Capsaicin could keep good inhibition activity during normal rice storage temperature. Capsaicin concentration 2.0 mg/mL had obvious inhibit effect on Aspergillus flavus and Aspergillus niger. Expansion pilot test showed that inhibition effect of 2.0 mg/mL capsaicin concentration on tested microorganism from high to low was Staphylococcus aureus, Salmonella. Bacillus subtilis, Aspergillus Escherichia coli, Mucor and Aspergillus niger. 4 Preparation technique optimization of capsaicin protective agent in rice storageBy single factor and orthogonal test, the study determined the optimal extraction parameter of capsaicin with ultrasonic wave and ethanol as solvent, which was ultrasonic time 50 minutes, particle size 80 mu, temperature 50℃, ratio of raw materials to solution 1:20. The extraction rate of capsaicin reached 86.32% after one extraction and capsaicin extracted from one gram chilli powder reached 19.8mg.Microencapsulation of capsaicin was prepared by complex coacervation of gelatin and CMC, glutamine transaminase as firming agent. The optimal technique parameters were as follows:wall material concentration 1%, gelatin/CMC 9:1, core/wall material ratio 1:1 and pH 4.6. The embedding yield was 92.53% and the embedding efficiency was 91.23%. Microencapsulation powder of capsaicin had irregular spherical shape, about 100μm particle size by scanning electron microscopy (SEM).Through microencapsulation the sense acceptability of capsaicin was improved. 5 Acceptability evaluation of capsaicin in rice storageThrough comprehensive consideration about safety, solubility, acceptability, stability and cost, ethanol was determined as the most suitable solvent of capsaicin protective agent in rice storage. Different capsaicin concentration, different treatment methods were used to sense evaluation of capsaicin protective agent. The results all belonged to sense acceptability range. Capsaicin residue in cargo rice was all less than 10% additive amount when adding different capsaicin content on rice 90 days later. If the maximum theory additive amount of 8g/t capsaicin protective agent in rice was counted, the capsaicin residue in cargo rice was less than 0.8mg/kg and hot taste residue could be completely accepted.