赋形剂对冷冻干燥桑葚果粉储藏稳定性的作用

Effect of Excipients on the Storage Stability of Freeze-dried Mulberry Powder

为探究赋形剂对冷冻干燥桑葚果粉储藏稳定性的影响,改善果粉在储藏过程中出现的品质劣化现象,通过检测果粉在不同储藏温度下的DPPH自由基清除能力、花色苷含量、色值及微观结构考察赋形剂对冻干果粉的影响。结果表明,果粉在低温环境(5℃)下保藏品质最好,添加麦芽糊精(maltodextrin, MD)、阿拉伯胶(arabic gum, AG)、乳清分离蛋白(whey protein isolate, WPI)均可提高果粉贮藏稳定性,表明赋形剂可通过提高反应活化能降低反应速率进而改善冻干桑葚果粉贮藏过程中的品质劣变。其中乳清分离蛋白及其复配物对果粉储藏稳定性改善效果最佳,相比于原果浆组(original pulp, OP),乳清分离蛋白及麦芽糊精复配组的DPPH自由基清除率在5℃储藏条件下,下降速率降低了46.2%,色泽提高速率为0.054/d,比原果浆组下降了64.8%,色差值活化能提高到37.03 kJ/mol。通过扫描电镜分析表明,添加赋形剂后的果浆能形成疏松多孔、表面光滑、孔径大小相近的微观结构,其中乳清分离蛋白形成延展性好、孔洞分布均匀、大小较一致、表面光滑的网状包覆层结构,从而提高干燥效率以减少营养物质和抗氧化性成分的损失。

To explore the effect of excipients on the storage stability of freeze-dried mulberry powder,and to improve the quality degradation of fruit powder during storage.The DPPH free radical scavenging ability,anthocyanin content,color value and microstructure of fruit powder at different storage temperatures were determinedandthey reflected the effect of excipients on freeze-dried fruit powder.The results suggested that the storage quality of fruit powder was best at low temperature(5℃).The addition of maltodextrin(MD),arabic gum(AG)and whey protein isolate(WPI)could improve the storage stability of fruit powder,which indicated that excipients could reduce the reaction rate by increasing the activation energy of reaction,and then delayed the quality deterioration of freeze-dried mulberry powder during storage.Among them,WPI and its complex exerted the best effect on improving the storage stability of fruit powder.Compared with the original pulp(OP)group,the DPPH scavenging ability inthe WPI and MDcomplex groups at 5℃decreased by 46.2%,and the color improvement rate was 0.054/d,which decreased by 64.8%compared with the OP group,and the color value activation energy increased to 37.03 kJ/mol.The analysis by scanning electron microscopy showed that the fruit pulp after the addition of excipients could form a loose and porous microstructurewith smooth surface and similar pore size.Among them,WPI formed a network coating structure with good ductility,uniform pore distribution,uniform size and smooth surface,which increased drying efficiency and reduced the loss of nutrients and antioxidant components.