Studies On Postharvest Fresh Keeping And Quality Security Of Cherry Tomato

By separating and qualitative analysis of pathogens in postharvest cherry tomato, main pathogens cause postharvest cherry tomato diseases were determined. Fungicides were screened out to control these main pathogens. Then the influence of preharvest fungicides spraying on fresh-keeping of postharvest cherry tomato was studied and the best fungicide was determined. Using orthogonal experimental design, the antistaling agent formula of cherry tomato was studied. Then the comprehensive fresh-keeping method including preharvest fungicides spraying and postharvest antistaling agent treatment was studied. Finally, the safety of SYP-Z048residue used in fresh keeping of cherry tomato was evaluated.Test results are as follows:(1)Separating and qualitative analysis of pathogens in postharvest cherry tomato5pathogens in postharvest cherry tomato were separated by separating and qualitative analysis of pathogens in postharvest cherry tomato:Alternaria, Botrytis cinerea, Fusarium culmorum, Phomopsis and Fusarium graminearum. In these pathogens, Alternaria and Botrytis cinerea mainly in summer, Alternaria, Fusarium culmorum, Phomopsis and Fusarium graminearum mainly in autumn. Alternaria was found both in summer and in autumn.(2) Pathogenicity of tested pathogens to cherry tomato5pathogens separated were inoculated back to postharvest cherry tomato to investigate pathogenicity the tested pathogens. The result showed that the5pathogens of Alternaria, Botrytis cinerea, Fusarium culmorum, Phomopsis and Fusarium graminearum all have the pathogens effects.(3) Antibacterial effect of fungicides to Alternaria and Botrytis cinereaBy determining EC50value of fungicides and sensitivity of pathogens, antibacterial effect of13fungicides to Alternaria and Botrytis cinerea was studied,7fungicides had good results both to Alternaria and Botrytis cinerea, they were SYP-Z048, prochloraz, eugenol, procymidone, polyoxins B,Trichoderma viride and Bacillus subtilis.(4)The influence of pre-harvest fungicides spraying on postharvest fresh keeping of cherry tomatoTwo cherry tomato varieties (Jinzhu and Red-cherry) were sprayed with SYP-Z048, Trichoderma viride and Bacillus subtilis before harvest, and their influence on postharvest fresh keeping of cherry tomato were contrasted. The result showed, pre-harvest spraying of S YP-Z048, Trichoderma viride and Bacillus subtilis dramatically reduced the incidence of disease and decay losses of postharvest Jinzhu and Red-cherry cherry tomato (P<0.05), Using the incidence rate of20%as the evaluation index, the storage period under20℃of Jinzhu and Red-cherry cherry tomato was extended to more than21d and15d. Pre-harvest spraying of SYP-Z048dramatically increased the content of Vitamin C in Jinzhu cherry tomato and reduced weight loss of Red-cherry cherry tomato during20℃storage(P<0.05). Pre-harvest spraying of Bacillus subtilis had a greater impact on reducing the lose of content of Vitamin C, titratable acidity and soluble solids of Jinzhu and Red-cherry cherry tomato during postharvest storage. The best preharvest spraying of fungicides was SYP-Z048, spraying concentration was0.4mL.L-1.(5)The result of antistaling agent formula of cherry tomato4factores including eugenol, Bacillus subtilis, citric acid and chitosan, were determined by single factor experiment using summer cherry tomato. By orthogonal experiment with L9(34) and verification test, the best antistaling agent formula of postharvest cherry tomato was0.015g.L-1eugenol,1×108cfu.ml-1Bacillus subtilis,1.0wt%citric acid and1.0wt%chitosan. The antistaling agent dramatically reduced the incidence of disease and decay losses of summer cherry tomato. Using the incidence rate of20%as the evaluation index, The storage period under20℃was extended to more than21d. The antistaling agent also dramatically reduced Vitamin C and weight loss of summer cherry tomato during20℃storage(P<0.05). In addition, acute toxicity test of the antistaling agent formula was studied, the result showed, acute oral toxicity (LD50) to both sexes (female, male) mice was more than40.0mL.kg-1weight, according to the LD50rating scales, the antistaling agent formula was Non-toxic.(6)The result of comprehensive fresh-keeping method to fresh keeping of cherry tomatoThe effect of comprehensive fresh-keeping method was investigated, as well as the effect of single factor application, using autumm cherry tomato, the results were as follows:①Preharvest spraying of SYP-2048with a concentration of0.4mL.L-1increased the Vc content of autumn cherry tomato, but the effect was not significant(P<0.05). And preharvest spraying of SYP-2048dramatically reduced the incidence of disease, weight loss and Vc loss of postharvest cherry tomato during storage, after21d storage, the incidence of disease was15.00±10.00%, lower than20%, and lower than33.33±2.89%of CK. ②The antistaling agent application dramatically reduced the incidence of disease, and weight loss and Vc loss of autumn cherry tomato during storage, after21d storage, the incidence of disease was6.67±2.88%, lower than20%, and lower than33.33±2.89%of CK. The effect of the antistaling agent application was better than pre-harvest spraying of SYP-2048.③The comprehensive fresh-keeping method was better than pre-harvest spraying of SYP-Z048and the antistaling agent application respectively. Using the comprehensive method, The storage period under20℃was extended to more than21d, and the incidence of disease was3.33±2.89%, was lower than20%, dramatically belower than15.00±10.00%of pre-harvest spraying of SYP-Z048and33.33±2.89%of CK, and also lower than6.67±2.88%of the antistaling agent application.The comprehensive fresh-keeping method included cherry tomato preharvest spraying of SYP-Z048with a concentration of0.4mL.L-1and the antistaling agent (0.015g.L-1eugenol,1×108cfu.ml-1Bacillus subtilis,1.0wt%citric acid and1.0wt%chitosan) application after postharvest.(7) The result of residue safety of SYP-Z048in pre-harvest cherry tomato fruitSYP-Z048in tomato fruit was determined by high performance liquid chromatography (HPLC). Samples of tomato fruit were extracted with ethyl acetate, extracting solution was cleaned up with C18-SPE column. The above solution was analysed by using High performance liquid chromatography combined with UV detector. The calibration curve was linear in the range of0.05mg.L-1～100mg.L-1, the regression equation was y=104040x+302.68, the correlation coefficient(r) was0.9999. The recoveries ranged from88.69%to96.82%with three addition levels(0.5、1.0、5.0mg.kg-1). The quantification limit (LOQ) of SYP-Z048in tomato fruit was0.01mg.kg-1.The effect of different storage temperature was also studied. The SYP-Z048residue in cherry tomato fruit was a declining curve both in pre-harvest and postharvest. The rate of decline of SYP-Z048in postharvest cherry tomato fruit was slower than pre-harvest cherry tomato fruit. The rate of decline of SYP-Z048residue in postharvest cherry tomato fruit was influenced by the storage temperature, the storage temperature was lower, the lower the rate of decline.The acceptable daily intake(ADI) and theoretical maximum residue limit (MRL) of SYP-Z048in cherry tomato were calculated to be0.1mg. kg-1and17.24mg. kg-1,, the safety of SYP-Z048residue in postharvest cherry tomato fruit was evaluated, The result showed that, two hours after pre-harvest spraying, the SYP-Z048residue was1.19mg.kg-1in Jinzhu cherry tomato, and was0.96mg.kg-1in cherry tomato dealing with comprehensive fresh-keeping method, both results were much less than the theoretical MRL. So SYP-Z048used on the basis of proposed dosage and interval before harvest, the postharvest cherry tomato was safe to eat.