Textural and structural changes of dehydrofreeze-thawed strawberry slices: Effects of different dehydration pretreatments / Cambios texturales y estructurales de rodajas de fresa deshidratadas y descongeladas: Efectos de diferentes pretratamientos de deshidratación

Abstract

Partial removal of water through air dehydration, dewatering-impregnation-soaking in concentrated solutions (DIS) or their combination, has been applied to strawberry slices before freezing in order to reduce structural cullapse after thawing. The changes produced at the structural level have been studied through both texture and microscopic analysis, so defining the structure-texture relation ships in the freeze-thawed fruit. Tissues subjected to DIS in a 60% (w/w) glucose solution for 4 hours at room temperature showed structural damage to the cell walls and cell ruptures, which are in agree ment with the observed decrease of texture. After thawing, the pre-dehydrated strawberry slices showed a much better tissue organization than the strawberry frozen without pretreatment. Air dry ing and the combination DIS-air drying gave the highest texture improvement of the fruit after thaw ing. A good agreement was obtained between structural and textural changes observed after both pre-dehydration and freeze-thawing of strawberry slices.