Grape pomace-derived pectin complex as a sole oleogelator: thermally induced structural reinforcement and application...

Oleogelation has emerged as a promising strategy for structuring unsaturated oils to address the conflict between food texture and health concerns. However, most oleogelators used in indirect methods rely on complicated pre-processing and lack natural sources. In this study, a pectin-protein-polyphenol complex derived from white grape pomace was investigated as a sole oleogelator to structure canola oil via an emulsion-templated approach. High oil contents of 94.9-97.9% (w/w) were achieved at pectin-to-oil ratios of 2:100-5:100 (w/v), with liquid oil effectively entrapped within the pectin complex network. Rheological analyses confirmed gel-like behaviour, with viscoelastic response associated with network density and integrity. The pectin complex network exhibited a capacity for thermal reinforcement, evidenced by increased viscoelastic moduli during the heating-cooling cycle and enhanced oil retention under thermal stress. Oil binding capacity remained up to 81.8% after heating at 180 °C followed by high-speed centrifugation. This reinforcement can be associated with hydrogen bond rearrangement and strengthened pectin-protein interactions within the network. Moreover, the oleogels exhibited improved oxidative stability, with total oxidation values reduced by 29.9-52.4% compared with unstructured oil in an accelerated oxidation test. Furthermore, when used to replace butter in pound cakes, the oleogels improved air cell formation compared with liquid oil and modulated cake crumb hardness, cohesiveness, and springiness. Overall, this study demonstrates that grape pomace-derived pectin complex can serve as a natural oleogelator with potential for thermally processed foods, while promoting the valorisation of grape pomace as a food waste resource.