Effect of pH and decoloring on apple pectin extraction with microwave-assisted

In order to improve the yield and quality of apple pectin, the effects of extraction pH by microwave-assisted extraction (MAE) and decoloring by using adsorption of resin were studied systematically by evaluating the yield and quality of apple pectin. The results showed that the higher pH, the lower yield of apple pectin, total mineral contents and galacturonic acid (GA), However, the higher degree of esterification (DE) and average molecular weight. The polyphenols in extracted pectin was increased as pH increased by MAE, indicating that higher pH was beneficial to extract polyphenols from apple pomace. Further investigations indicated that the GA and DE of the pectin recovered from apple pomace didn’t change significantly after decolourisation among all the treatments. The a*, b*, C* value, browning index and total phenolic content of decoloured sample significantly decreased while the H° value increased, which showed that decolourisation by using adsorption of resin significantly improved the color of apple pectin. It can be concluded that the parameters of pH=1.50 provide one of the most promising conditions for extracting pectin from apple pomace.