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Chlorophyll Degradation in a Spinach System at Low and Intermediate Water Activities
Author(s) -
LAJOLO F. M.,
MARQUEZ U. M. LANFER
Publication year - 1982
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1982.tb12929.x
Subject(s) - pheophytin , spinach , chemistry , degradation (telecommunications) , chlorophyll , spinacia , chlorophyll a , glycerol , activation energy , water activity , pigment , photosynthesis , environmental chemistry , photochemistry , botany , photosystem ii , water content , biochemistry , chloroplast , organic chemistry , biology , telecommunications , geotechnical engineering , computer science , engineering , gene
Chlorophyll degradation in blanched freeze‐dried spinach puree was studied in model systems as a function of water activity (a w ), pH, temperature and also in the presence of glycerol, a water‐binding agent. For a w > 0.32 the most important mechanism of chlorophyll degradation is the transformation into pheophytin. The reaction can occur at very limited water concentration and has a first order dependence on pH, water activity and pigment concentration. The addition of glycerol increases the rate of degradation of chlorophyll. At temperatures higher than 56.7°C and a w = 0.11, the energy of activation increased, indicating different mechanisms. For temperatures below 38°C the rate tended to increase instead of decreasing with decreasing temperatures because of changes in the sorption isotherm (increase of water content) caused by the shift in the temperature.