Microwave and solvent extraction of Opuntia cladode mucilage: Functional characterization and application as natural...

Growing health concerns associated with cholesterol and allergenic potential of egg yolk have increased the demand for plant-based hydrocolloid substitutes for emulsion based food systems. This study investigated the potential application of mucilage derived from Opuntia ficus-indica and Opuntia stricta cladodes as a natural hydrocolloid substitute for egg yolk in mayonnaise formulations. Mucilage was extracted using two methodologies- solvent and microwave extraction- from peeled and unpeeled cladodes. The mucilage powders were characterized in terms of extraction yield, physicochemical, structural, and functional properties. Mayonnaise formulations were prepared by partially replacing egg content with mucilage at 25% (M25) and 50% (M50) levels, as well as egg-free formulations incorporating 25% and 50% mucilage (EFM25 and EFM50). Results revealed that the highest extraction yield (15.95%) was obtained from the unpeeled cladodes of O. ficus-indica using the microwave method, whereas the lowest yield (5.01%) was observed in solvent extracted, peeled O. stricta. Mucilage obtained by microwave extraction showed higher carbohydrate content and molecular weight (up to 4234.20 kDa), with glucose as the predominant monosaccharide, particularly in O. ficus-indica. While peeling improved mucilage purity of O. ficus-indica, it was associated with a reduction in total phenolic content (from 13.75 to 10.60 mg GAE/g) and antioxidant activity. Partial substitution (M25 and M50) significantly improved emulsion stability and textural properties compared to the control. Specifically, M50 demonstrated the highest hardness (86.5 g), heat stability (80.15%), and microstructural uniformity compared to the control (25 g and 54.15%, respectively). Partial replacement improved sensory acceptance compared to control (with M25 scoring 4.3 in overall acceptability versus 3.6 for the control), while egg free samples showed the lowest sensory scores (<3.0). Therefore, Opuntia mucilage can be recommended as a natural hydrocolloid for egg substitution in mayonnaise formulations.