Effects of different drying methods on appearance, microstructure, bioactive compounds and aroma compounds of saffron (Crocus sativus L.)

In our study, saffron stigmas were subjected to vacuum drying (VD), microwave drying (MD), oven drying (OD), infrared drying (ID) and freeze drying (FD), respectively. Quality attributed of the dried samples were compared in terms of appearance color, microstructure, bioactive compounds and aroma compounds. Results showed that FD, ID and MD were the better drying methods to preserve bioactive or aroma compounds, respectively. Meanwhile, FD retained good appearance color, complete initial cell structure and intact pollen grains, ID led to shortest drying time (0.7 h). However, FD time was the longest (47 h), in addition, the cost and energy consumption of FD and ID were relatively high. Therefore, considering about energy consumption and the quality of saffron, MD might be the most suitable method for both keeping content of crocins and aroma components, and its drying time was short (1.9 h).