Effect of different enzyme-treatments on propertiesof pitaya fruit peel powder

High quality of fruit powder from pitaya fruit peel was made by spray drying technology and the color，nutrient composition，rheological property and antioxidant activity of fruit powder treated by different enzymes werecompared. The results showed that the fruit powder without enzyme-treatment showed a better color，and retained thecolor of fresh pitaya fruit peel（ho=1.81），while the color of sample with enzyme-treated and heated inclined to yellow（ho=80.6）. The moisture content of untreated sample was 6.23%，which limited its storage. A higher content of totalflavonoids（70.45 mg/g）was detected in untreated sample compared with enzyme-treated fruit powder. The contentof Vitamin C in enzyme-treated sample was the highest（0.46 mg/g），followed by untreated sample（0.40 mg/g）. Thesample heated with enzyme-treated showed the lowest Vitamin C content（0.34 mg/g）. Angle of repose of untreatedsample was 45.48°，and had a worse dispersity. Both of the results of FRAP and DPPH showed that the untreated fruitpowder sample had a higher antioxidant activity，followed by enzyme-treated sample and heated sample.