Strawberry-hydrocolloids dried by continuous cast-tape drying to produce leather and powder

Abstract Cast-Tape Drying (CTD) is an innovative and competitive technique to dehydrate fruit and vegetable pulps on a continuous scale, to produce leathers, flakes, and powders. The hydrocolloids maltodextrin, starch, and pectin were added to a strawberry pulp as carrier agents (CA). Ostwald and Herschel-Bulkley's models fitted well to rheological data of strawberry pulp and strawberry-CA suspensions. A pseudoplastic behavior was observed for all samples, which is ideal for spreading on the CTD support. All drying curves showed a constant and a falling rate period, and the time to reach a constant moisture content was dependent on the sample (between 20 and 40 min). After drying, products were removed as leathers, and the CA addition contributed to the easier detachment of the materials from support. All leathers were homogeneous, with thicknesses in the range of 0.2–0.4 mm, and the strawberry-CA leathers exhibited a slight color difference compared to the pure strawberry. Sorption isotherms of the strawberry leathers adjusted well to the GAB model. The volatile compounds in the strawberry pulp were strongly modified by drying, with the addition of maltodextrin and pectin promoting the preservation of some of the strawberry original volatiles; however, pectin has shown a few new compounds. The presence of hydrocolloids in strawberry powders increased the Tg and the dispersion (except when maltodextrin was added) in water, compared to pure strawberry powders.