Degradation Kinetics of Gamma Amino Butyric Acid in Monascus‐Fermented Rice
2015
The present study investigated the effect of heat on the reaction kinetics of γ‐amino butyric acid (GABA) degradation in Monascus‐fermented rice (MFR). At pH 8.0 and 121C temperature, the GABA content decreased rapidly (from 57.1 ± 0.2 to 6.9 ± 0.2) as the time interval was increased from 15 to 120 min. The thermal degradation of GABA follows the first‐order reaction kinetics. The temperature dependence of rate constants follows the Arrhenius relationship, with an activation energy value of 101.5 kJ/mol (80–121C, r² = 0.96). GABA is easily degraded when MFR is heated to a temperature of 121C. More than 70% of the GABA content can be salvaged by limiting the heat treatment of MFR to below 80C. PRACTICAL APPLICATIONS: Monascus‐fermented rice is being used as a nutraceutical due to the presence of different heart healthy ingredients like monacolin K or lovastatin, GABA and dimerumic acid. However, during processing of Monascus food, there may be degradation of bioactive ingredients. The present research data are given information about how different processing parameters affect the ingredient quality and will find applications in industries and researchers involved in formulating and processing Monascus nutraceuticals.
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