Effects of Different Color Protection and Drying Methods Treatment on the Quality of Asparagus Powder

Different color protection agents were used to soak and spray the asparagus for color protection due to improve and compare the browning problem of asparagus during the process of hot air, vacuum freezing and microwave drying. The results showed that the quality of nutrition and color of asparagus powder with color protection was better than that without color protection. The color protection effect of Hu3 was significantly better than that of Hu2 and Hu1 (P<0.05). The synergistic use of drying method and color fixative was better than that of single drying. Among them, the retention degree of phenols, structural integrity, color and antioxidant capacity of asparagus powder treated by color fixative and vacuum freeze drying (VFD) were the best. The structure of asparagus powder treated by color fixative and hot air drying (HAD) was sparse and dispersed, and the content of phenols, color and antioxidant capacity were lower than VFD. However, the asparagus powder obtained by color fixative and microwave drying (MD), was bright yellow, with the worst nutrition and color quality. In addition, compared with soaking, the water soluble dietary fiber (SDF) content of sprayed asparagus powder was higher, and the adsorption capacity of glucose and cholesterol was better, but the color protection effect of the former was better. The results of principal component analysis showed that the total phenol, rutin, physicochemical and functional properties of asparagus powder were highly correlated with its nutrition and color quality. The top three asparagus powder in terms of comprehensive quality were Hu3-Soak-VFD, Hu2-Soak-VFD and Hu3-Spray-VFD. The last three were Hu1-Spray-MD, Hu2-Spray-MD and control-MD. The results of this study provide a theoretical basis for improving the quality of dried asparagus products.