Abstract

We investigated the effect of two heating patterns, quick and gradual, on the relative degradation rate of chlorophyll, carotenoid, and the three intermediates, Protoporphyrin IX(PPIX), Magnesium protoporphyrin IX(MGPP) and Protochlorophyllide(Pchlide), of chlorophyll biosynthetic pathway in three vegetable leaves. The data showed that (1)all pigments declined under both patterns of heating, however, the relative degradation rate of quick heating is greater than that of gradual heating; (2)The mechanism of all investigated pigments is a two-step reaction; (3)The relative degradation rate of chlorophyll is slower than that of carotenoid; (4)The relative degradation rate of chlorophyll a is faster than of that of chlorophyll b; (5)the relative degradation rate of protochlorophyllide is slower than that of magnesium portoporphyrinIX, which is slower than that of portoporphyrin IX; (6)nutrient content after gradual heating within 30 min is better than quick heating within the same period. We concluded that the degradation of leaf in nature is different from that in the heating condition of water.

Keyword: Cholorophyll, Carotenoid, Heating Pattern, Magnesium protoporphyrin IX, Pigment, Protochlorophyllide, Protoporphyrin IX