Suhl Hyung Joo, Noh Dong Ouk, Kang Chang Soo, Kim Jin Man, Lee Seog Won
Department of Food and Nutrition, College of Health Sciences, Korea University, 1 Jeongneung-dong, Sungbuk-ku, Seoul 136-703, Korea.
Nahrung. 2003 Apr;47(2):132-5. doi: 10.1002/food.200390024.
The effects of temperature and pH on color degradation kinetics of the mulberry fruit extract were investigated. The absorbance at 510 nm was decreased with increase of heating time, but that at 420 nm was increased with the increase of heating time at 100 degrees C. The change of the browning index (A510/A420) was increased with increase of pH and was lower at pH 2.0 than that at pH 5.0. The browning index variation was adequately described by both the first-order and the zero-order kinetic. However, the zero-order kinetic model was proposed because of the better fit. According to the Arrhenius model, the activation energies for the browning index in the range of 80-100 degrees C for the four different pH values were 30.68 kJ/mol for pH 2.0, 35.87 kJ/mol for pH 3.0, 42.67 kJ/ mol for pH 4.0, and 43.49 kJ/mol for pH 5.0.
研究了温度和pH值对桑椹果实提取物颜色降解动力学的影响。在100℃下，随着加热时间的增加，510nm处的吸光度降低，但420nm处的吸光度随加热时间的增加而升高。褐变指数（A510/A420）的变化随pH值的升高而增大，在pH 2.0时低于pH 5.0时。一级动力学和零级动力学均能较好地描述褐变指数的变化。然而，由于拟合效果更好，故提出零级动力学模型。根据阿伦尼乌斯模型，在80-100℃范围内，四种不同pH值下褐变指数的活化能分别为：pH 2.0时为30.68kJ/mol，pH 3.0时为35.87kJ/mol，pH 4.0时为42.67kJ/mol，pH 5.0时为43.49kJ/mol。
