ACID REMOVAL FROM SUNFLOWER PECTIN GEL THROUGH ETHANOL WASHING

Sunflower heads remaining after seed removal is a potential source of low-methoxyl pectin. After extraction and acid precipitation of pectin gel, aqueous ethanol solution was used to purify the pectin. Ethanol washing of nitric acid-precipitated gel in a countercurrent process at 20 degrees C removed acid. Concentration of nitric acid in the ethano l solvent varied depending on washing time, acid concentration in the gel, ethanol in washing solution, and ratio of gel to washing solution . Gel/solvent ratios of 1:2, 1:1.8, and 1:1.5 increased gel pH at the rate of 0.024, 0.022, and 0.018 pH units per min, respectively. Diffus ion rare constants of nitric acid from the gel to washing solution wer e 5.281 x 10(-2), 4.855 x 10(-2), and 4.282 x 10(-2) min(-1), respecti vely. A cubic regression equation was developed to express the relatio nship between nitric acid concentrations and pH.