Analysis of cell-wall pectin from hot and cold break tomato preparations

The initial processing of tomatoes includes a break step, which involves rapid heating of the freshly chopped tomatoes to >90 degrees C for hot break, or 60-77 degrees C for cold break. It is believed that pectolytic enzyme deactivation is the key element in the hot break step; therefore the pectin content of the different products should be qualitatively distinct. There are two general sources of pectin in a tomato fruit: the middle lamella which is rich in homogalacturonan, and the cell-wall. In this study, a 0-min or 24-min hold time (room temperature) for the chopped tomatoes preceded the break step to replicate hot and cold break, respectively, with minimum variation in the processing. The cell-wall pectin was then isolated and analyzed for the carbohydrate composition, degree of polymerization, and degree of esterification. The results showed no observable differences in pectin isolated from the two preparations, indicating that there is no significant pectolytic activity in the cell wall during the 24 min hold time; thus, the pectolytic enzymes probably act on the lower ester, middle lamella pectin in cold break products. Published by Elsevier Ltd.