Effects of microwave heating on concentration properties and quality attributes of blueberry–grape blended pulp

Abstract

Blended blueberry–grape pulp (BBGP) was concentrated using microwave heating concentration (MHC) to evaluate the effects of microwave intensity (2–6 W/g), blueberry-to-grape mass ratio (1:1–1:7), citric acid addition (0.2%–0.4%), and granulated sugar addition (10%–15%) on temperature, moisture content, anthocyanin retention ratio, soluble solids content, and sensory quality. Microwave intensity and blueberry-to-grape mass ratio each exhibited a biphasic effect on anthocyanin retention and sensory scores, with optimal levels around 4 W/g and 1:3 mass ratio, whereas soluble solids content remained unaffected by variations in these parameters or citric acid concentration. Citric acid addition enhanced anthocyanin stability but impaired palatability at excessive levels, while granulated sugar addition did not significantly influence anthocyanin retention yet effectively modulated soluble solids and sweet-sour balance, with 12.5% yielding the highest sensory performance. The recommended processing parameters for MHC of BBGP are 4–6 W/g, 1:3 blueberry-to-grape mass ratio, 0.3% citric acid, and 12.5% granulated sugar. These findings provide practical guidance for optimizing MHC processes to produce high-quality blended fruit concentrates such as BBGP.