Study On Effects Of Processing On Pesticide Residues In Orange Juice And Peels

Citrus is the most important fruit in the world. For orange juice, which is the largest one of citrus industry, its quality and safety is closely related with consumers'health and the development of juice industry in China. Besides, citrus peels and residues from juice processing are important resource of animal feeds, while is an enrichment part for pesticide residues, thus, pesticide residues in citrus peels and residues may be a very important risk for human's health, from meat products through food chain. Therefore, it will play an evident role in reducing food safety risks to study changes of pesticide residual contents in orange juice and peels by processing procedures and their relative control measures.In this experiment, firstly, the GC testing methods for 16 pesticides in orange juice or peels were established, and the results were shown as follows: for orange peels, the average recovery rates of standard addition for 16 pesticide residues ranged from 70.9% to 108.4%, and values of CV ranged from 1.4% to 11.8%; for orange juice, the average recovery rates of standard addition for 16 pesticide residues were 83.0%～104.2%, and values of CV were 1.0%～9.1%; moreover, GC detection limits of 16 pesticides ranged from 0.05μg/kg to 2.30μg/kg. In a word, the GC testing methods were able to completely satisfy requirements of detecting multiple pesticide residues.Effects of processing procedures, including squeezing & abstracting, filtration, degassing and microwave sterilization, as well as different filtration or clarification methods such as common filtration, centrifugation and ultra-filtration, on pesticide residues in orange juice were attained from this experiment: as the first procedure of orange juice processing, squeezing & abstracting treatment could significantly increase contents of chlorothalonil, dicofol, procymidone, pyrethroid, omethoate, isocarbophos, dimethoate and chlorpyrifos residues (the increase rates invloved 16% to 253%); filtration evidently reduced contents of chlorothalonil, dicofol, procymidone, pyrethroid, dichlorvos, triazophos and chlorpyrifos residues (the decrease rates ranged from 11.75% to 28.24%); however, no significant changes of all pesticide residues in orange juice could be observed after degassing and short time microwave sterilization. On the other hand, contents of most pesticide residues were able to be significantly reduced by common filtration, centrifugation and ultra-filtration (the decrease rates: 6.54%～98.34%), moreover general trends on reducing pesticide residues by these three methods could be concluded as that: common filtration < centrifugation < ultra-filtration.Effects of washing, drying and fermentation treatments on pesticide residues in orange peels and marcs were listed as follows:(1) Four washing methods were able to evidently decrease pesticide residues in and on orange peel, and their reducing rates ranged from 25.93% to 76.06%; besides, the trend of reducing pesticide residues of these four washing methods could be observed: tap water washing < 25mg/kg ClO₂ < 100mg/kg ClO₂ < ultrasonic washing.(2) Sun, oven and microwave drying treatments could significantly decrease absolute amounts of all pesticide residues in orange peels and marcs (25.30%～75.83%, 45.75%～99.24% and 77.60%～99.83%, respectively), of which microwave drying was the most effective treatment, at the same time was fast and easy to control, having a bright future.(3) The effects of Candida tropicalis and Aspergillus usamii fermentation on pesticide residues in the sweet orange peel were investigated in this paper. Among these 16 pesticide residues, the reducing rates of chlorothalonil and dichlorvos residues in these peels were the highest by two fermentation courses (72.87%-100%); on the other hand, the reducing rates (27.95%-62.28%) of organophosphorus pesticide residues without omethoate in the two fermenting courses were generally higher than those of pyrethroid, dicofol and procymidone pesticides, as well as significantly higher than CK; furthermore, the effects of Candida tropicalis on reducing pesticide residues in the fermented peels were generally superior to the Aspergillus usamii treatment.In conclusion, from this experiment, it was a little difficult to reduce pesticide residues in orange juice by processing treatments except filtration; on the other hand, pesticide residues in the orange peels and marcs could be to various extents decreased by washing, drying and fermentation. Besides, it is very important to establish some available management systems such as GMP and HACCP in the processing course for controlling pesticides in orange products; and it is also indispensable to enforce GAP during pre-harvest period. In a word, the principle of"from farm to table"is extremely necessary to realize the true safety of citrus products.