An ultrasound-assisted procedure for the extraction of pectins from grape pomace with citric acid as the
extracting agent was established. A Box–Behnken design(BBD)was employed to optimize the extraction
temperature (X1: 35–75 ◦C), extraction time(X2: 20–60min)and pH(X3: 1.0–2.0)to obtain a high yield of
pectins with high average molecular weight(MW) and degree of esterification (DE)from grape pomace.
Analysis of variance showed that the contribution of a quadratic model was significant for the pectin
extraction yield and fo rpectin MW whereas the DE of pectins was more influenced by a linear model. An
optimization study using response surface methodology was performed and 3D response surfaces were
plotted from the mathematical model. According to the RSM model,the highest pectin yield(∼32.3%) can
be achieved when the UAE process is carried out at 75 ◦C for 60min using acitric acid solution of pH 2.0.
These pectic polysaccharides,composed mainly by galacturonic acid units(