Effects Of Different Coating Treatments On Antioxidant Contents And Antioxidant Ability In Huang Guan Pear

In this paper, post-harvest Huangguan pear was the test material and was coatedwith calcium chloride, chitosan and pullulan. The paper was focused on the effects ofdifferent coating treatments on antioxidant activity and antioxidant contents inpostharvest pear during storage.The experiment mainly determined that the contentsof total phenolic, phenolic compositions(by HPLC analysis) and total flavonoid inpeel and pulp of the pear, and the activity changes of SOD,POD,CAT,PPO andantioxidant activity（DPPH, ABTS, FRAP）in peel and pulp. It is aimed at exploringthe correlation of antioxidant substances, antioxidant enzymes and antioxidantcapacity in pear fruit, revealing the changes of antioxidant capacity in law.(1) The HPLC analysis showed that the contents of the chlorogenic acid,arbutin, catechin, caffeic acid were detected in Huang guan pear. But there was nocaffeic acid in pulp by HPLC analysis.Phenolic content of chlorogenic acid accountedfor about50%of the total substance was the role of the major PPO substrate. Thecalcium chloride, chitosan and pullulan coating treatments could inhibit the decline oftotal phenolic, phenolic compositions and total flavonoid, and then maintained ahigher glutathione content during0±1℃storage (p<0.01).The end of storage, thecontent of total phenolic, phenolic compositions,total flavonoid and glutathione incontrol fruit is lower than treatments; and the content of antioxidant substances in peelis much higher. Chitosan treatment was the best.(2) The antioxidant enzymes results showed that pears coated with calciumchloride, chitosan and pullulan treatments during storage compared with the control,delayed the SOD, CAT activity decreasing speed and inhibited POD, PPO activityincreasing speed（p<0.05）. The end of storage,SOD, CAT activity in control is lowerthan in treatments while POD, PPO activity in control is higher than intreatments.And POD, SOD, CAT activity in peel is higher than in pulp，but PPOactivity result is opposite.In a word,chitosan and pullulan treatments were the best inHuangguan pear,but in pulp,calcium chloride, treatments was the best（p<0.01）.(3) The use of calcium chloride, chitosan and pullulan coatings by themselvesseem to substantially contribute to enhancement of antioxidant activity（DPPH, ABTS,FRAP）of pears (p<0.01).The end of storage,antioxidant activity in control is lower than in three treatments.In a word,chitosan and pullulan treatments were the best inHuangguan pear,but in pulp,calcium chloride, treatments was the best（p<0.01).(4) The correlation coefficients between the measured characteristics andantioxidant activity in pear peel show that the measured characteristics andantioxidant capacity of FRAP have higher correlations for:Chlorogenic acid, catechin,total flavone, total phenolic compounds, CAT, SOD, glutathione was significantlynegative correlation;The measured characteristics and antioxidant capacity of ABTS have highercorrelations for:Chlorogenic acid, arbutin, total flavone, total phenolic compounds,such as CAT, SOD, glutathione is negative correlation;The measured characteristics and antioxidant capacity of DPPH have highercorrelations for:Chlorogenic acid, caffeic acid, total flavone, catechins, SOD,glutathione is negative correlation.In addition, the results highlight the importance of using effective coatings toprotect "Huang guan" pears with no reduction in shelf life. In a word, calciumchloride, chitosan and pullulan coatings may also form a protective barrier on thesurface of fruit to reduce antioxidant compounds loss and slow decline of antioxidantactivity. Therefore, the application of three coatings as good storage methods could befavorable in extending shelf-life and maintaining quality and to some extent,controlling decay of pears.