不同干燥方法对番木瓜粉品质及抗氧化活性的影响

摘要

比较不同干燥方法对番木瓜粉品质和抗氧化活性的影响,为番木瓜干燥加工提供理论基础和依据.本研究以水分活度、玻璃化转变温度、晶体形态、微观结构和抗氧化活性为评价指标,分别对热风干燥(HAD)、微波泡沫干燥(MFD)和真空冷冻干燥(VFD)所得番木瓜粉进行分析.结果表明:VFD样品的水分活度与褐变程度最低,而MFD样品的水分活度与褐变程度最高.MFD样品的玻璃化转变起始温度为(34.9±1.1)℃,显著高于HFD、VFD样品的(13.6±0.4)、(16.5±0.7)℃.VFD样品呈现出相对稳定的非晶体结构特征,而其他两种干燥样品则为晶体结构.VFD番木瓜粉的微观结构呈骨骼状和多孔结构,MFD样品呈不规则形态,边缘锋利,HFD样品呈光滑片状结构.在抗氧化活性方面,HFD、MFD、VFD样品的多酚含量分别为(6.11±1.01)、(4.36±0.62)、(4.32±0.87) mg/g,从ABTS自由基清除能力来看,MFD＞HFD＞VFD,从DPPH自由基清除能力来看,HFD＞MFD＞VFD,VFD样品中多酚的含量最低且抗氧化活性相对最差.综合比较,MFD能生产出较高品质的产品,可以作为一种新型的番木瓜粉干燥方法.%In order to compare the effects of different drying methods on the quality and antioxidant activity of papaya powder and to provide a theoretical basis for drying papaya,the study analyzed the papaya powder obtained from hot-air drying(HAD),microwave foam dry ing(MFD)and vacuum freeze drying(VFD) method,using water activity,glass transition temperature,crystal morphology,microstructure and antioxidant activity as the evaluation indexes.The results showed that the moisture activity and browning degree of the VFD samples were the lowest,while that of the MFD samples were the highest.The starting temperature of the glass transition of the MFD sample was (34.9 ± 1.1)℃,higher than that of the HAD and VFD sample,which was (13.6 ± 0.4)℃ and (16.5 ± 0.7)℃,respectively.The VFD papaya powder exhibited a amorphous structure,while the other two drying samples showed crystalline structures.The microstructure of the HAD powder was smooth and flaky.The particles of the VFD powder showed a skeletal-like structure with more porous compared to the others.The MFD material exhibited irregular morphology with sharp edges.In the aspect of antioxidant activity,the content of polyphenols in the HAD,MFD and VFD sample was (6.11 ± 1.01),(4.36 ± 0.62),(4.32 ± 0.87)mg/g,respectively.And the powder of HAD and MFD had a stronger radical scavenging ability of DPPH and ABTS than the VFD powder.The content of polyphenols in the VFD sample and its antioxidant activity was the lowest.By comparison,higher quality products could be produced using MFD,which could be used as a new drying method of papaya powder.