EXTRACTION TEMPERATURE AND pH AS DECISIVE FACTORS FOR THE YIELD AND PURITY OF GRAPE POMACE PECTIN

Abstract

The purpose of this paper is the use of grape pomaces, obtained by processing two different Vitis vinifera varieties (Rară Neagră and Fetească Neagră) from 2019 harvest, cultivated in the Bugeac area, Republic of Moldova, as a source of unconventional pectin. Pectin was extracted under the following conditions, citric acid used as extractant for 3 h of extraction, 125-200 µm of grape pomace particle size and solid to liquid ratio 1:10. The variables which were varied were temperature (70, 80 and 90 °C) and pH (1, 2 and 3). So, pectin yield and galacturonic acid content were determined under the influence of extraction temperature and pH. The obtained results demonstrated that the extraction conditions (temperature and pH) have a significant impact on the yield and purity of pectin from grape pomace. The highest influence on pectin yield was determined by pH 1 (15.54% and 9.96% for Fetească and Rară Neagră grape pomace pectin, respectively) and temperature of 90 °C (7.34% and 7.56% for Fetească and Rară Neagră grape pomace pectin, respectively). The same tendency is observed for galacturonic acid content.