Structural integrity, bioactive components, and physico-chemical characteristics of Kashmiri saffron (Crocus sativus L.) as affected by different drying techniques

Abstract

This research investigated the effects of shade drying (SD), freeze drying (FD), vacuum drying (VD) and cabinet drying (CD) on saffron stigmas. Results showed FD was most effective in preserving quality, followed by VD, CD, and SD. Drying methods had no significant (p ≥ 0.05) effects on ash, moisture, and acid-insoluble ash contents. Freeze-dried saffron had the lowest water activity (0.533), bulk density (0.145 g/mL), and volume shrinkage ratio (28), with superior color retention (a* 40.09, b* 17.43) and anthocyanin content (0.73 mg C3GE/g DM). FTIR analysis indicated better crocin preservation with FD. Freeze-dried saffron also exhibited highest DPPH radical scavenging capacity (59.63 %), FRAP values (47.26 mmol/kg), ABTS⁺ values (75.51 %), total phenolics (72.41 mg GAE/g), crocin (901.44 mg/g), picrocrocin (9.48 mg/g) and safranal (1.80 mg/g) contents. Microstructural analysis confirmed better cellular integrity with FD, making it the most effective method for preserving saffron quality at -80 °C for 44 h.

Keywords: Bioactive compounds; Density; Microstructure; Saffron stigmas; Volume shrinkage ratio.