Effects of maltodextrin on hygroscopicity and crispness of apple leathers

Abstract

Fruit leathers are snacks made by drying a layer of fruit puree until a leathery consistency is achieved. Fruit leathers are mainly composed of low weight carbohydrates, which have low glass transition temperature (Tg) and are highly hygroscopic, so the product becomes sticky when stored at ambient relative humidity. In this work, apple leather strips (ALS) were prepared. Some formulations contained maltodextrin in order to decrease hygroscopicity. ALS hygroscopicity was evaluated by sorption studies, and crispness by mechanical and acoustic properties. Maltodextrin addition decreased the hygroscopicity of ALS. The addition of 15% maltodextrin reduced the moisture uptake by 45% to samples conditioned at 44%RH. At low moisture contents, the ALS become crispy. The crispness was lost as the moisture content of samples increase, following the modified Fermi equation behavior. The transition from crispy to soft material occurred at a water activity between 0.22 and 0.44. Addition of 15% maltodextrin increased the puncture force, puncture deformation and maximum amplitude up to 143%, 35% and 140% respectively. The variation of molecular weight and moisture content of snack products creates different texture and sensations at biting and chewing.