Influence of thermal treatments on microscale release of nutraceutical compounds in syneresis liquids from frozen blood orange purées

Publication date: Available online 25 April 2015 Source:Food Structure Author(s): Ada Brambilla , Gianni Bertolo , Anna Rizzolo Phytochemicals release from blood orange (Citrus sinensis (L.) Osbeck cv Tarocco) fruit into the liquid fraction of thermally treated homogenate products was studied by means of a complementary biochemical and micro-structural approach. Thermal treatments were applied either before (10min steam-blanching, BL) or after puréeing (30min autoclave pasteurization, PAST) of thawed (24h, 4°C, NB) IQF fruit. NB, BL and PAST homogenates (200g), packed in sealed plastic vessels, were frozen and stored at −20°C; liquid fractions were separated from the pulps by syneresis upon thawing (24h at 4°C). Physico-chemical and colour parameters and total carotenoids of the samples, as well as anthocyanin content, viscosity and turbidity values of the separated liquids were measured, while histochemical profiles of fruit, purées and syneresis liquids were investigated by bright-field and fluorescence microscopy. PAST purées released a lower amount of syneresis serum (52%), compared to BL (57%) and NB purées (59%). Crystals, plastids, droplets and amorphous components were identified as constituents of syneresis liquids from frozen purées. Blanching of the fruit increased the release of membrane-bound carotenoids, insoluble pectinous materials and hesperidin crystals from the pulps into the liquid fractions, but decreased the anthocyanin content of synere...

Source: Food Structure - April 25, 2015 Category: Food Science Source Type: research