Tuning physical properties of tomato puree by fortification with grape skin antioxidant dietary fiber

Grape skins recovered from winemaking by-products were investigated for use as sustainable, antioxidant fiber-rich ingredient for the innovation of low-energy dense tomato puree. Six tomato purees fortified with grape skin antioxidant fiber, with varying particle size distribution, and two control tomato purees were studied. Physical parameters of purees were analyzed upon mixing and either an intensive heat treatment or an optimized heat treatment designed to achieve six decimal reductions of a target microorganism (Alicyclobacillus acidoterrestris) as recommended for pasteurization of acidic fruit products. Mixing of grape skin antioxidant fiber with tomato purees led to a decrease in both surface-weighted mean diameter (Sauter mean diameter, d(3,2)) and volume-weighted mean diameter (d(4,3)) values and an increase in span. Changes in these descriptors were most significant in purees added with the smallest particle sizes. Thermal stabilization of purees slightly decreased the d(3,2) values further and increased d(4,3) values, suggesting concomitant occurrence of particle disaggregation and formation of flocs within the food matrix. Phenolic solubility was inversely correlated to d(3,2) values. Bostwick consistency, storage (G') and loss (GaEuro(3)) moduli, and complex viscosity (eta*) increased in the fortified purees. The eta* values displayed a positive correlation with d(4,3) values. Variations in Hunter colorimetric parameters were within the acceptability threshold. Overall, the information obtained provides knowledge to assist development of fiber-rich, low-energy dense fruit purees.