Development and Characterization of Whey Protein-Based Hydrogels for Sugar-Free Protein-Fortified Rose Jam Applications

The growing demand for sugar-free and protein-enriched fruit preserves has driven interest in alternative structuring systems development that provide both desirable texture and nutritional benefits. This study aimed to develop and characterize whey protein isolate (WPI)–based hydrogels in combination with low methoxyl pectin (LM-pectin) and to evaluate their potential application in sugar-free, protein-fortified rose jam. WPI was incorporated at various concentrations (1, 3, and 5% w/v), and the effects on gel strength, water-holding capacity (WHC), and syneresis (%) were systematically investigated. The results demonstrated that increasing WPI concentration significantly enhanced gel strength and WHC, indicating improved network formation and water retention within the hydrogel matrix. The synergistic interaction between WPI and LM-pectin contributed to improved structural integrity. Application in sugar-free rose jam demonstrated that WPI-based hydrogels successfully provided jam-like texture, acceptable spreadability, and enhanced protein content without added sugar. These findings highlight the potential of WPI–LM pectin hydrogels as a functional and sustainable ingredient for the development of sugar-free fruit-based products, supporting innovation in health-oriented food formulations.