RESPONSE SURFACE METHODOLOGY BASED OPTIMIZATION AND QUALITY EVALUATION OF ORANGE PEEL POWDER-ENRICHED KULFI

Abstract

This study aimed to optimize the incorporation of orange peel powder (OPP) and mix concentration in kulfi using response surface methodology (RSM) and evaluate the quality characteristics of the optimized product. A central composite rotatable design was employed with OPP concentration (2.0–3.0%, w/v) and mix concentration (1.0 1.75-fold) as the independent variables. Color and appearance, taste/flavor, sweetness, texture, and overall acceptability were evaluated using a 9-point hedonic scale, while sugar and stabilizer-emulsifier levels were kept constant based on preliminary trials. Quadratic models adequately described the sensory responses, with R² values ranging from 0.8375 to 0.9231 and a non-significant lack of fit for all responses. Numerical optimization, based on maximizing color, flavor, and overall acceptability while maintaining the other sensory responses within the experimental range, yielded an optimum formulation containing 3.0% OPP and 1.75-fold mix concentration, with a desirability of 0.88. Validation of the optimized formulation showed no significant difference (p > 0.05) between the predicted and observed values for the sensory responses. Compared with the control, the optimized kulfi showed no significant differences in fat, protein, and total sugar contents, whereas carbohydrate, ash, total solids, and energy values differed significantly (p < 0.05). The findings demonstrate that OPP can be incorporated into kulfi at an optimized level while maintaining acceptable sensory characteristics and modifying its compatibility. Industrial relevance Orange processing generates large volumes of peel waste which  has substantial disposal and environmental costs. This study provides dairy and frozen-dessert manufacturers with a validated RSM-based formulation and process window (OPP concentration and mix concentration) for converting orange peel into a value-added functional ingredient in kulfi, a widely consumed traditional Indian frozen dessert. The optimized formulation offers a scalable route to reduce citrus by-product waste while diversifying functional frozen-dessert product lines for health-conscious consumers.