Structural, functional, and emulsifying properties of low-methoxyl pectins extracted from Eurotium...

This study investigated the effects of solid-state fermentation of grape skins by Eurotium cristatum on the structural and functional properties of the extracted pectin. After fermentation, the pectin yield increased from 10.50 % to 13.17 %, while the methoxyl content (MeO) significantly decreased, indicating a successful transformation from high-methoxyl pectin (HMP) to low-methoxyl pectin (LMP). Thermal analysis revealed an increase in enthalpy change from 29.85 J/g to 95.34 J/g, accompanied by a rise in melting temperature from 199.7 °C to 207.3 °C, suggesting enhanced thermal stability. Additionally, the molecular weight (Mw) of pectin decreased markedly from 45 kDa to 37 kDa, and a higher proportion of rhamnogalacturonan-I (RG-I) regions was inferred, indicating substantial depolymerization and main-chain restructuring. Functionally, the pectin extracted form fermented grape skins (PEFGS) exhibited improved water-holding capacity (WHC) and oil-holding capacity (OHC), increasing to 1.76 g/g and 4.42 g/g, respectively. Besides, PEFGS could form stable emulsions with weak gel-like properties under both pH 2.5 and pH 6.0 conditions. Notably, emulsions prepared at pH 6.0 showed superior stability and emulsifying performance. These findings suggest that PEFGS holds promise as a natural emulsifier and rheology modifier for applications in the food industry.