European Journal of Nutrition & Food Safety

Karonda and mango pulps were blended to develop a fruit syrup and optimise the proportions of karonda pulp, mango pulp, sugar, and citric acid using response surface methodology. A four-factor Box–Behnken design comprising 27 experimental runs was used to evaluate total soluble solids, titratable acidity, ascorbic acid, flavonoids, β-carotene, total phenolic content, antioxidant activity, viscosity, colour values (L*, a*, and b*), and browning index. The experimental factors were varied within 25–30 g karonda pulp, 15–20 g mango pulp, 60–70 g sugar, and 1–2% citric acid. Quadratic models were fitted to the measured responses, and model adequacy was assessed using analysis of variance, coefficients of determination, adjusted and predicted R² values, adequate precision, and desirability. Fruit pulp and sugar generally increased soluble solids, viscosity, phytochemical responses, and antioxidant activity, whereas the effects of citric acid varied among responses. The reported optimised formulation comprised 25 g karonda pulp, 17.5 g mango pulp, 65 g sugar, and 1 g citric acid. This formulation provided a desirability value of 1.000 and represented a balance among physicochemical, nutritional, phytochemical, antioxidant, viscosity, and colour attributes. Across the experimental treatments, colour variation was moderate, with treatment-dependent changes in L*, a*, b*, and browning index. The study demonstrates the applicability of Box–Behnken response surface methodology for simultaneously evaluating multiple formulation variables and quality responses in karonda–mango blended syrup.