摘要
利用自制高温热氧化装置和气相色谱法分别测定棕榈酸、油酸、亚油酸、亚麻酸在不同温度下的氧化降解曲线,同时采用微分法对热氧化降解反应动力学方程的参数(氧化活化能Ea,反应级数n,反应速率常数k,指前因子A)进行了计算,进而确定了反映棕榈酸、油酸、亚油酸、亚麻酸在高温下热氧化降解历程的宏观反应动力学模型。结果表明:棕榈酸热氧化降解反应动力学模型为r_A=-dcA/dt=9. 292×10^(66)exp(-648. 492/RT) c_A^(6. 504);油酸热氧化降解反应动力学模型为r_A=-dc_A/dt=3. 213×10^(59)exp(-548. 724/RT) c_A^(5.201);亚油酸热氧化降解反应动力学模型为r_A=-dc_A/dt=2. 865×10^(57)exp(-515. 468/RT) c_A^(3.220);亚麻酸热氧化降解反应动力学模型为r_A=-dc_A/dt=4. 451×10^(39)exp(-350. 851/RT) c_A^(2.108)。4种脂肪酸的动力学方程分别反映了其化学反应速率与反应温度和底物浓度的关系,同时揭示出不同脂肪酸热氧化的特性:随着不饱和度的升高,脂肪酸的热氧化稳定性降低;不饱和度越高,脂肪酸热氧化受自身浓度的影响越小;不饱和度越高,温度对其反应速率的影响越大。
The oxidation degradation curves of palmitic acid,oleic acid,linoleic acid and linolenic acid at different temperatures were determined by self-made high-temperature thermal oxidation apparatus and gas chromatography( GC). The parameters of thermal oxidation degradation reaction equation were calculated by differential method,including oxidative activation energy Ea,reaction order number n,reaction rate constant k and pre-factor A. The macroscopic reaction kinetics equations reflecting the thermal oxidation degradation of palmitic acid,oleic acid,linoleic acid and linolenic acid at high temperatures were determined. The results showed that the oxidation degradation kinetics models for different fatty acids were obtained as follows: palmitic acid,rA=-dcA/dt =9.292 × 1066exp(-648. 492/RT) cA6. 504;oleic acid,rA=-dcA/dt = 3. 213 × 1059 exp(-548. 724/RT) cA5.201;linoleic acid,rA=-dcA/dt = 2. 865 ×1057exp(-515. 468/RT) cA3.220;linolenic acid,rA=-dcA/dt = 4. 451 × 1039 exp(-350. 851/RT)cA2.108. The kinetics equations revealed the relationship between the oxidation reaction rate and the temperature( T) and substrate concentration( cA),and revealed the thermal oxidation characteristics of different fatty acids: as the unsaturation degree increasing,the thermal oxidation stability of fatty acids decreased,the higher of the unsaturation degree,the less of substrate concentration influenced on the thermal oxidation fatty acid,the greater of temperature influenced on the reaction rate.
作者
刘剑
刘元法
李进伟
LIU Jian;LIU Yuanfa;LI Jinwei(State Key Laboratory of Food Science and Technology,School of Food Science and Technology,Jiangnan University,Wuxi 214122,Jiangsu,China)
出处
《中国油脂》
CAS
CSCD
北大核心
2019年第1期35-40,共6页
China Oils and Fats
基金
国家自然科学基金(31571878)
江苏省苏北科技专项(BN2016137)
关键词
特征脂肪酸
热氧化
动力学
氧化稳定性
characteristic fatty acid
thermal oxidation
kinetics
oxidative stability
