Physicochemical properties of dried Guizhou as affected by pretreatments, drying techniques and storage period
2021
Phungamngoen, Chanthima | Detchewa, Pakkawat | Tanongkankit, Yardfon | Moongngram, Anuchita
The effects of pretreatment methods (hot-water blanching, steam blanching and acetic acid soaking) and drying techniques (hot-air drying, vacuum drying and freeze drying) on the physical properties and antioxidant activities of dried Guizhou are investigated in this study. Results show that blanching improved the drying rate, and was faster than untreated and acetic acid treated samples. Vacuum drying resulted in slower drying than hot air. Samples subject to hot-air drying and vacuum drying exhibited more shrinkage than those subjected to freeze drying. Dried-blanched samples had greener and darker color than acetic acid pretreated and untreated dried samples. Freeze-dried samples had the highest total phenolic compounds and antioxidant activity determined by DPPH assay. Moisture content, water activity, color change (ΔE) of hot air dried, vacuumdried and freeze-dried samples gradually increased throughout the 6-month storage period, while total phenolic compounds and DPPH radical scavenging activity showed a decreasing trend. Aluminum foil provided better protection against moisture uptake by dried samples than polypropylene containers. Freeze-dried samples kept in aluminum foil at room temperature gave the longest shelf life. Results suggested that pretreatment by blanching, suitable drying methods and aluminum packaging improved physical properties and protected phenolic acid content of dried Guizhou.
显示更多 [+] 显示较少 [-]