Pectic substances in 'Concord' grapes with relation to maturation in 1963
Proc. Amer. Soc. hort. Sci 92: 319-22
Pectic substances and maturity indexes of Concord grapes were studied over a 99-day period. In contrast to the slight changes in maturation indexes occurring before 19 August, total pectic substances decreased considerably. During the period of commercial harvest, after 20 September, pectic substances decreased only slightly. The composition of pectic substances in the marc was fairly constant at about 1 % acetyl, 60-70 % methyl esterification and 17-22% anhydrouronic acid.