The influence of acid volume, ethanol-to-extract ratio and acid-washing time on the yield of pectic substances extraction from peach pomace

The effects of acid volume, acid-washing time and pH variation during different stages of pectic substances extraction process on the yield of pectic substances isolation from dried mixed varieties of peach pomace is investigated. Ethanol-to-extract ratio (ER) as a new parameter and extract evaporation are defined to investigate their influence on the yield of pectic substances extraction. Pectic substances extraction method was carried out by acid washing of pomace with 0.1 N HCl at constant temperature and their precipitation with suitable amount of 96% w/w ethanol. Experiments were performed at 60 °C with different volumes of HCl (35, 65, 105, and 130 ml), acid-washing times of 30, 60 and 180 min, and ER of 0.5, 1 and 1.5. The effect of ER on the degree of esterification (DE) of pectic substances was determined by the Fourier transform infrared (FTIR) method.