Kinetic analysis of S-allyl-L-cysteine production in the homogeneous reaction of garlic paste
In order to ef fec tively pro duc e S-allyl-L-cysteine(SAC) with the endo genous γ-glutamyltranspeptidase(γ-GTP) in garlic,the effects of Ca2+concentration and water-solid ratio in reaction liquid on SAC yield and γ-GTP activity in the homogeneous reaction of garlic paste were discussed,and then SAC production was analyzed kinetically.The experimental results showed that the initial γ-GTP activity reached maximum of 12.7 mU/g at the Ca2+concentration of 5 mmol/L. The final SAC yield increased linearly with the initial γ-GTP activity. Under the condition of liquid-solid ratio at8, temperature at 37 ℃, a Ca2+concentration at 5 mmol/L and reaction at 8 h, the SAC yield reached maximum of 793.4 μg/g-DM. Under the condition of liquid-solid ratio at 8, temperature in the range of 20℃ to 37 ℃ and Ca2+concentration in the range of 0 mmol/L to 5 mmol/L, the production of SAC could be simplified to one-order reaction, and the relationship of reaction rate constant and temperature could be expressed by an Arrhenius equation. When the Ca2+concentration increased from 0 mmol/L to 5 mmol/L, the activation energy of SAC production decreased from 80.3 kJ/mol to a minimum of 70.9 kJ/mol. The kinetic analysis in the present study provided theoretical basis and technical data for controlling the SAC production process in the homogeneous reaction of garlic paste.