Changes in Pectic Substances of Tomato Fruit during Ripening and Juice Processing

Abstract

Pectic substances in tomatoes harvested at three different stages during ripening, and in tomato juices prepared from fully ripened fruits by cold break process(CBP)and hot break process(HBP)was examined. The pectic substances were assayed quantitatively and investigated by DEAE-cellulose column chromatography and gel filtration with Sephadex G-200.
As tomatoes got ripened, water soluble-, 0.4% sodium hexamethaphosphate soluble- and 0.05% hydrochloric acid soluble-pectins were decreased. However, the ratio of water soluble pectin to total pectin got increased. DEAE-cellulose colum chromatographic pattern of water soluble pectin, showed hardly any change. Two peaks were shown in chromatogram of gel filtration: the major was eluted at the void volume(M. W., 2×10₅ or more)and the minor was located at the volume of three to four times as much as the void volume(M. W., 1×10₃).
Pectin contents in CBP juice rapidly decreased as the time proceeded. Conversion of the pectin into low methoxyl content and smaller molecular weight conponent was found. Contents of pectin in HBP juice was high and showed little change in methoxyl content and molecular weight.
From the results, HBP in tomato processing was re-evaluated as the favorable method for their products.