Valorisation of Citrus sinensis peel biomass into functional slice jam: Optimisation using central composite design and quality characterisation

Abstract

The valorisation of agro-industrial waste aligns with sustainability efforts and supports innovation in functional food development. This study explores the conversion of Citrus sinensis peel waste into a nutrient-enriched, sliceable jam using Central Composite Design (CCD). A systematic analysis was conducted to determine the different concentrations of pectin and C. sinensis peel puree affecting the important quality parameters such as pH, hardness, moisture content, vitamin C, and total phenolic content (TPC). Thirteen experimental runs were conducted, and the responses were modelled using second-order polynomial equations. Post hoc comparisons using Tukey’s HSD confirmed significant differences (p < 0.05) among treatments, allowing the identification of the best-performing formulation. The optimised formulation, comprising 91.398 g of C. sinensis peel puree and 6.038 g of pectin, yielded a product with a nutrient-enriched of total phenolic content (24.378 mg GAE/g), vitamin C (1677.17 mg/100 g), an improved texture (96.37 mJ), moisture content (55.25%) and desirable acidity of pH 2.89. The findings highlighted the ability of C. sinensis peel waste to improve the nutritional quality and functionality of gel-based food products. This study presents an innovative strategy for creating sustainable and ready-to-eat jams supporting food waste reduction and the advancement of a more resilient food system.