干燥方式对火龙果果皮理化特性的影响

Effects of different drying methods on physicochemical qualities of the pitaya pericarp

采用热风干燥、真空干燥和真空冷冻干燥处理火龙果果皮,探讨干燥方式对果皮的理化特性影响。结果表明,热风干燥后的果皮的亮度(L*)、红绿值(a*)、黄蓝值(b*)与新鲜果皮和其他2种干燥方式处理后果皮均存在显著性差异(P <0. 05);真空冷冻干燥后果皮收缩率、孔隙率和复水率优于热风干燥和真空干燥;不同干燥方式后果皮的脆性和弹性存在显著性差异(P <0. 05),真空冷冻干燥后果皮口感最适合直接食用;果皮复水后与新鲜果皮相比,TPA指标存在显著性差异(P <0. 05);在营养方面,新鲜果皮最好;不同干燥方式处理后果皮相比,热风干燥后果皮的总抗氧化性和清除自由基能力最好,真空冷冻干燥后果皮的色素和总黄酮含量最高,真空干燥后果皮营养无明显优势。

The pitaya pericarp was treated by hot air-drying,vacuum drying and vacuum freeze-drying,and the effects of different drying methods on the physical and chemical properties of the pericarp were discussed.The results indicated that the luminance(L^*),red and green value(a^*),yellow and blue value(b^*)of the pericarp after hot air-drying were significantly different from the fresh pericarp and others treated by other two drying methods.The shrinkage rate,porosity and rehydration rate of the pericarp after vacuum freeze-drying were greater than that of hot air-drying and vacuum drying.There were significant differences in brittleness and elasticity among different drying methods(P<0.05).The taste of pericarp after vacuum freeze-drying was the most suitable for direct consumption.Compared with fresh pericarp,there were significant differences in TPA index after rehydration(P<0.05).Indeed,fresh pericarp was the best in terms of nutrition.Comparing to pericarp dried with different methods,the pericarp's total antioxidant activity and the ability for eliminating free radicals were the strongest after hot air drying.Pericarp treated with vacuum-freezing drying had the maximum contents of pigments and general flavonoids.In comparison,pericarp dried by vacuum drying had no evident superiority regarding its nutrition.