Effects of pretreatments of sliced vegetables with trehalose on drying characteristics and quality of dried products

Abstract

Effects of pretreatments with trehalose on drying of sliced vegetables (potato and carrot) were experimentally investigated. Two different pretreatment methods were tested. Sliced vegetables were steam-blanched and then immersed in a sugar solution. In another method sliced vegetables were coated with sugar powder, and then steam-blanched. Solid gain and water loss during pretreatment were measured. The isothermal drying experiments were carried out at 303, 313 and 323 K. Sorption isotherms of dried samples were determined by a standard gravimetric method at 303, 313 and 323 K. Pretreatments reduced the water content of vegetable samples due to osmotic dehydration. Less shrinkage, better colour properties and better cell reconstruction properties were observed for samples pretreated with trehalose either with solution or with powder.