A comprehensive analysis and comparison between vacuum and electric oven drying methods on Chinese saffron (Crocus sativus L.).

ABSTRACT

The red stigmas of saffron are one of the most expensive spices in the world and serve as a traditional Chinese medicine. More saffron has been cultivated in China, and different drying technologies have been studied. However, a comprehensive and comparative analysis of different drying approaches has not been well studied. In this study, we compared electric oven and vacuum oven drying approaches on saffron. We found saffron was dried quicker under high vacuum drying mode with high temperature and the quicker drying rate provided, the more open microstructural interstices on the saffron surface. Both methods were best fit to Midilli and Kucuk model. Besides, the coloring, aroma and bitterness strength after drying showed the similar results. In sum, our data suggested the optimal drying temperature was 100 °C for 20 min for two evaluated methods, however considering the machine cost, the electric oven drying would be the first choice.