| This topic was about to overcome the main problems including the turbidness of soup, white spot, and pusticide residues, etc. in the canned mandarin orange on the basis of modern food scientific theory through researches, achieved the aim of enhancing the quality of the canned mandarin orange, and offered theoretical foundation and basic data for the high quality canned mandarin orange production.1 Qualitative analysis of white spot ingredient in the canned mandarin orange by infrared spectrum proved the main ingredient of white spot was hesperidins.2 The best application conditions of hesperidinaseThe suitable pH value of hesperidinase was 3. 5, and it was steady between pH 3.0 and pH 6.0. The suitable temperature of hesperidinase' s application was 60℃ (pH 3. 5),and above pH 3.5, after 5 minutes' manipulation of heating at the temperature of 60℃, the residues of hesperidinase activity was 100%; after 5 minutes' manipulation of heating at the temperature of 70℃, the residues of hesperidinase activity was 90%. But at the pH value of 2.5, the stability of hesperidinase was weak compared with the former.If the syrup was not adjusted the pH value, after 120 minutes' manipulation of heating at the temperature of 60℃, the residues of hesperidinase activity was above 50%; after 240 minutes' manipulation of heating below the temperature of 50℃, the residues of hesperidinase activity was above 85%. But in the hesperidinase solution (not syrup), after 60 minutes' manipulation of heating at the temperature of 60℃, the residues of hesperidinase activity was only several per cent. It was better to increase the enzyme in the syrup below the temperature of 50℃. The syrup which pH value was adjusted and temperature was controlled had better control the pH value 3. 0 and the temperature below 40℃ then increased the hesperidinase into it. 3 The suitable application amount and best temperature of sterilizationIts standard amount used for each tin (4 OZ MC tin) was 0. 03g or 0. 05g, and both amount could prevent the turbidness of soup and the white spots on the orangepetal. But hesperidinase was easy to deactivate under low temperature. So the control of pH value and temperature of syrup in the process of pasteurization was important. When the canned mandarin orange were heated up to sterilize and the amount of hesperidinase was 0. 05 g/tin, the center temperature of 4 OZ MC tin could be at the temperature of 74.5C, 73.3C and 71.3 C, and the results were all good. When the amount of hesperidinase was 0. 03 g/tin, the center temperature of 4 OZ MC tin must be under the 74C. Just like the examples show, the application of hesperidinase in the large-scale tin such as 15 OZ MC tin, etc. besides 4 OZ MC tin all could prevent the white spots from producing. 4 The analysis of pesticide residues in the canned mandarin orangeThe micro-chemical method and solid phase extraction technology was used for extraction and purification. The SPBTM-1701 quartz capillary column was chose. Shimadzu GC -9AM and Shimadzu GC - 17AM gas chromatography with FPD as detective apparatus separately analyzes the pesticide residues- methylamine phosphorus in the complex canned mandarin. The results of recovery were 86. 30% and 86. 12%. The Precision of method was good and the linear coefficient was 0.9968. Detective limits was 0.002 mg/kg satisfied enough to the residues analysis request. The method was fast and accurate.This topic selected 16 samples of canned mandarin orange, of them 12 samples had methylamine phosphorus residues, moreover methylamine phosphorus residues of several samples achieved several dozens ppb, seriously affecting the canned mandarin orange quality. In order to avoid the pesticide residues in the canned mandarin orange, the amount of pesticide in the time of mandarin planting should be controlled, and should avoid the pollution of orange peel during the process of peeling as well, because the pesticide residues mainly remained in the orange peel.
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