Influence of storage on the volatile profile, mechanical, optical properties and antioxidant activity of strawberry spreads made with isomaltulose

This work represents the final step of a series of studies on the formulation of strawberry products with partial replacement of sucrose by healthier sugars such as fructose and isomaltulose. Previously, quality parameters of the formulated products such as colour, texture, rheology, aromatic profile and sensory evaluation were assessed. As a final step, in the present work, the volatile profile evolution of a strawberry spread-product during 90 days of storage at room temperature (20 °C), and its relation with some physicochemical properties (aw, pH, texture and colour) and antioxidant activity as well as anthocyanin content were studied.Most of the volatile compounds modified their concentration during storage; some of them totally disappeared but 13 new compounds were formed: (methyl-2-methyl butyrate, E-2-butenal, 2-butenal-2-methyl, 2-buten-1-ol, 2-penten-1-ol, 2-etil-1-hexanol, 6-methyl-5-hepten-2-one, acetic acid, propanoic-2-methyl acid, butyric acid and butyric-2-methyl acid). Storage led to a dark pink colour and an increase in consistency and adhesiveness while the antioxidant activity considerably increased (from 18±2% to 94±2% DPPH inhibition).Levels of citric acid and pectin influenced colour, texture and antioxidant activity as well as retention and formation of aromatic compounds, especially in fructose–isomaltulose products. Correlations via a PLS were found between the aromatic profile of the products after storage and some of their quality parameters such as texture, colour and antioxidant content. Future research might involve correlation and identification of specific volatiles with different quality parameters.