Enzymatic de-esterification and depolymerization of apple pomace (Malus domestica var. Blanca de Asturias) pectin impacts lipid digestion in vitro

Different degree of esterification (DE) and molecular weight (Mw) of apple pomace pectin (APP) were evaluated for the effect on lipid digestibility. APP was isolated from variety "Blanca de Asturias" by acidic extraction to obtain pectin with 66% of DE, and 348 kDa Mw. APP was de-esterified with pectinmethylesterase (PME) obtaining APP with DE of 57, 42, and 39%. APP was depolymerized by endo-polygalacturonase (PG) or pectate lyase (PL), and three modified APP fractions were obtained with Mw of 309, 166, and 162 kDa or 241, 205, and 184 kDa for PG-APP or PL-APP fractions, respectively. A considerable reduction in the composition of neutral sugars was observed in the modified samples, which is related to the reduction of the branched region of the pectin. Oil-in-water emulsions prepared with 2% (w/w) of different APP samples were shear thinning and viscosity was 2–20 times higher in pectin added emulsions. Inhibition of lipid digestibility measured in a multiple stage in vitro model showed that APP and modified APP with higher DE significantly reduced lipid digestibility by 25%. The results contribute to the design of higher fat foods and putative higher consumer acceptability. The addition of pectin with certain structural characteristics, can reduce the degree of lipid digestibility, that may help mitigate public health problems such as obesity.