超高压协同pH值对哈密瓜汁中脂氧合酶钝化效果的研究

Effect of Ultra High Pressure-pH Synergistic Treatment on the Inactivative Effect of Lipoxygenase in Hami Melon Juice

为了研究超高压和pH值单独及协同处理对哈密瓜中脂氧合酶（LOX）的钝化效果，采用柠檬酸和碳酸钠调整哈密瓜汁的pH值为2—11，设定实验压0．1～500MPa，温度20-60℃，保压时间0-40min。结果表明，哈密瓜中LOX的最适pH值为7～8，最适温度为30—35℃；常温下单纯超高压处理鲜榨哈密瓜汁很难钝化LOX，调整酸碱度协同超高压处理，能很好地钝化LOX；在pH值4-5，温度25℃和55℃，压力300～500MPa，保压时间5～30min时，LOX的钝化符合一级反应动力学。

The influence ofpH, Uhra-High Pressure （UHP） and pH-nltra high pressure synergistic treatment on the activities of Lipoxygenase （LOX） in hami melon juice were studied in this paper. The UHP treatment was carried out under the conditions of pressure 0.1-500 MPa, temperature 20-60 ℃, holding time 0-40 min, and different pH value （adjusted by citric acid and sodium carbonate： 2-11） . It was showed that the optimum pH value range of LOX 7.0-8.0. The optimum temperature range was 30-35℃. It was very difficult to inactivate LOX by simple UHP treatmenL However, pH-ultra high pressure synergistic treatment proved to efficiently induce enzyme inactivation. The experimental data followed first-order reaction kinetics under the following experimental conditions： pH4-5, temperature 25℃, 55 ℃, pressure 300-500 MPa and holding time 5-30 rain.