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REACTION AT LIMITED WATER CONCENTRATION. 2. Chlorophyll Degradation
Author(s) -
LaJOLLO F.,
TANNENBAUM S. R.,
LABUZA T. P.
Publication year - 1971
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.1365-2621.1971.tb15542.x
Subject(s) - pheophytin , chlorophyll , chlorophyll a , chemistry , spinach , degradation (telecommunications) , chlorophyll b , light harvesting complexes of green plants , photochemistry , photosynthesis , biochemistry , photosystem ii , photosystem , organic chemistry , telecommunications , computer science
SUMMARY— Chlorophyll degradation was studied as a function of water activity (A w ) in freeze‐dried blanched spinach puree and in model systems containing cellulose‐citrate buffer and chlorophyll a. At 37°C and A w higher than 0.32, the most important mechanism of chlorophyll degradation is conversion to pheophytin. The rate of chlorophyll a transformation is 2.5 times faster than for chlorophyll b. The relation between A w and log time for 20% chlorophyll degradation is linear and the chlorophyll/pheophytin ratio is useful for storage prediction as a function of A w (down to A w 0.32). At A w lower than 0.32, the rate of pheophytin formation in spinach is low. New products are formed which can interfere with spectrophotometric determination of chlorophylls and pheophytins. The possibility of removal of Mg from the porphyrin ring of chlorophyll a was shown in model systems even at A w below BET (Brunnauer‐Emmet‐Teller) monolayer coverage.