Glass transitions and state diagrams for typical natural fruits and vegetables

State diagrams of freeze-dried camu-camu ( Myrciaria dubia (HBK) Mc Vaugh) pulp with and without maltodextrin addition

“…T g moved towards lower temperatures with increasing moisture content due to the plasticizing effect of water. The same trend was observed by several authors working with other freezedried fruits (Roos, 1987;Sá & Sereno, 1994;Sobral, Telis, Habitante, & Sereno, 2001;. Ice formation was observed in samples with water activities higher than 0.75 for the natural pulp and higher than 0.84 for pulp with maltodextrin.…”

Water sorption isotherms and phase transitions in kiwifruit

“…Similar curves were obtained for the other samples submitted to different pretreatments. DSC curves were similar to those determined Table 2 Parameters of BET (a w < 0.5) and GAB models fitted to experimental data for samples submitted to different treatments (R 2 : determination coefficient) by others authors in other fruits in the same domain of a w (Roos, 1987;Sá & Sereno, 1994). The thermograms obtained showed the typical second-order transition, the glass transition of the amorphous materials formed during each pre-treatment in kiwifruit, that produce a step change in the heat flow due to changes in heat capacity at the temperature of phase transition.…”

“…State diagrams have been reported for grape (Roos, 1987;Sá & Sereno, 1994), strawberry Roos, 1987;Sá & Sereno, 1994), apple (Bai, Rahman, Perera, Smith, & Melton, 2001;Sá, Figueiredo, & Sereno, 1999;Sereno, Sá, & Figueiredo, 1998) pineapple ) mango (Ayala, Walter, Martínez-Monzó , Fito, & Chiralt, 2002) and persimmon (Sobral, Telis, Habitante, & Sereno, 2001), but no data were found for kiwifruit.…”

“…Several authors reported that water crystallization in fruits becomes relevant from a w values greater than 0.80 (Roos, 1995;Sá & Sereno, 1994;Welti-Chanes et al, 1999). Water soluble compounds are the main components in the solid fraction of the fruits, the ratio of soluble to insoluble ones being in the order of 10-1.…”

Some thermal properties of fresh and osmotically dehydrated Kiwifruit above and below the initial freezing temperature

“…Also some information is available for hot-air dried or freeze-dried and rehydrated fruits and vegetables (Sá and Sereno, 1994;Sá et al, 1998Sá et al, , 1999Sereno et al, 1998;Kasapis et al, 2000;Telis and Sobral, 2001;Bai et al, 2001;Baroni et al, 2003). However, this information is not valid for osmotically dehydrated foods whose composition and structure is different from that of those hotair dried, due to soluble solids uptake and less structural damage during the OD process.…”