Optimization of pectin extraction assisted by microwave from apple pomace using response surface methodology

Microwave-assisted extraction (MAE) was applied for pectin extraction from the dried apple pomace and response surface methodology (RSM) was used to optimize the effects of processing parameters of extraction on the yield of pectin. Four independent variables such as extraction time (min), pH of HCl solution, solid:liquid ratio and microwave power (W). The optimal conditions were determined and tri-dimensional response surfaces were plotted from the mathematical models. The F-test and p-value indicated that both the extraction time and pH of HCl solution had highly significant effects on the response value and the quadratic of microwave power also displayed significant effect, followed by the interaction effects of pH and solid:liquid ratio. Considering the efficiency, the economization of energy and the feasibility of experiment, the optimum conditions of pectin extraction were extraction time 20.8 min, pH 1.01, solid:liquid ratio 0.069, microwave power 499.4 W. Application of MAE in the extraction from dried apple pomace dramatically reduced extraction time. The optimal predicted pectin yield of 0.315 g from the dried apple pomace (2 g) was obtained. Close agreement between experimental and predicted yields was obtained.