Effect of Vacuum and Active Packaging on the Qualitative Characteristics and Microbial Load of Dry Saffron Stigma (Crocus sativus L.)

Saffron is known as the most expensive spice in the world due to its many medicinal properties. This plant has many secondary metabolites, the most important of which are crocin, picrocrocin, and safranal. Different drying and storage conditions have caused a decrease in the quality and effective ingredients of saffron stigma, which has reduced its value and credibility for export. This research aimed to explore methods for preserving the quality and microbial characteristics of dry saffron stigma during storage. Saffron stigmas were packed using three-layer packages (polyethylene-polyester-polyethylene) under three atmospheres: air, vacuum, and N2.The packages were then stored at room temperature for 80 days. Once every 20 days, the concentration of oxygen gases, carbon dioxide, physicochemical properties, total microbial load and sample scanning image were measured. The results showed that the best samples for maintaining the physicochemical characteristics of saffron stigma were packages containing nitrogen-rich atmosphere, so the amount of crocin and picrocrocin decreased by 0.1% and 0.3%, respectively, while the amount of safranal increased by 0.3%. Also, the total microbial load decreased by one logarithmic cycle compared to the first day of storage in packages containing a vacuum atmosphere. Electron microscope images also showed that the samples under nitrogen atmosphere, like the control sample, had cell swelling and bubble-shaped particles along with cell membrane rupture and cell collapse.