Changes in chemical composition, volatile compound, and bioactive compounds retention in shallots (Allium ascalonicum L.) under different drying methods
Jiranan Ratseewo, Theeraphan Chumroenphat, Hua Li, Sirithon Siriamornpun
Abstract
Shallots ( Allium ascalonicum L.) are widely used in culinary and medicinal applications due to their rich bioactive compounds and health benefits. This study examines the effects of freeze drying, sun drying, and hot air drying at 40, 60, and 80 °C on chemical and bioactive compounds in shallots. Hot air drying at 80 °C had the highest total phenolic and flavonoid contents. Freeze drying increased syringic, p -coumaric, protocatechuic, vanillic, and ferulic acids. Quercetin was highest in freeze drying. Apigenin increased in samples that was dried by hot air drying at 80 °C. Proline was the major amino acid; arginine increased by 34 % in sun drying. Fourier Transform Infrared Spectroscopy (FTIR) revealed polysaccharides, lipids-proteins, and amino acids. Eucalyptol was the predominant volatile component in fresh shallot and most preserved by freeze drying. The results underscore the significance of choosing suitable drying methods to preserve shallot bioactive compounds and antioxidant properties. • Freeze-drying best preserves shallot microstructure and bioactive compounds. • Hot air drying at 80 °C yields the highest total phenolic and flavonoid contents. • Syringic, p -coumaric, and ferulic acids increased with freeze-drying treatment. • Drying methods significantly reduce fructooligosaccharides, sucrose, and stachyose. • Amino acid and volatile profiles varried significantly with different drying methods.