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Studies on Domestic Dates. III. Effect of Temperature on Some Chemical Changes Associated with Deterioration a, b
Author(s) -
MAIER V. P.,
SCHILLER FRANK H.
Publication year - 1961
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.1365-2621.1961.tb00401.x
Subject(s) - chemistry , browning , mole , peroxidase , hydrolysis , sucrose , oxygen , invertase , carbon dioxide , oxidative phosphorylation , activation energy , enzyme , nuclear chemistry , biochemistry , organic chemistry
SUMMARY The rates of various reactions associated with deterioration of whole dates such as darkening, pH decrease, sucrose hydrolysis, and oxygen and carbon dioxide gas exchange were studied at 28.4, 38.0, and 49.0°C and their apparent activation energies calculated. Also, changes in the activities of phenolase and peroxidase were followed in dates stored at 38.0°C. It was shown that dates darken by both oxidative and nonoxidative browning pathways, which respectively have apparent activation energies of 23.4 and 34.5 kcal/mole. Demonstration of enzymic browning in ground date tissue suggested that oxidative browning of whole dates is enzyme‐catalyzed. Oxygen absorption and carbon dioxide production gave respective apparent activation energies of 17.6 and 25.3 kcal/mole in unheated dates, and 19.0 and 27.4 kcal/mole in heated dates, indicating the existence of enzymic and non‐enzymic sources. The nonenzymic nonoxidative decrease in pH and invertase‐catalyzed sucrose hydrolysis had apparent activation energies of 22.8 and 26.0 kcal/mole, respectively. Apparent phenolase activity increased during storage of dates, whereas apparent peroxidase activity decreased.