Effect of Acid Value on TBHQ and BHT Losses in Heating Oils: Identification of the Esterification Products of TBHQ and Free Fatty Acids

The loss of phenolic antioxidants is one of the major problems associated with the food frying process. As temperature increases and heating time is prolonged, losses of both tertiary butylhydroquinone (TBHQ) and butylated hydroxytoluene (BHT) are significantly increased. In this work, the effect of different types of free fatty acids (FFA) and the acid value (AV) of soybean oil (SBO) on TBHQ and BHT losses during heating were systematically studied. The results showed that the higher the AV of SBO at 120 or 180 °C, the greater the TBHQ loss. The type of FFA also had an observable effect on TBHQ losses at both temperatures, whereas FFA type had no effect on BHT losses. Employing high performance liquid chromatography and liquid chromatography–mass spectra (LC–MS analysis, it was determined that esterification of TBHQ with FFA (C_8:0, C_18:0, C_18:1) occurred at 120 or 180 °C, whereas esterification of BHT with FFA (C_8:0, C_18:0, C_18:1) in SBO was not observed. Nuclear magnetic resonance analysis showed that esterification occurred at the 4-position of TBHQ.     

Natural antioxidants produced in oxidized lipid/amino acid browning reactions

1-Substituted pyrroles (1 and2) and1-substituted 2-(1′-hydroxypropyl)pyrroles (3–5) were produced in reactions between a lipid peroxidation product, 4,5(E)-epoxy-2(E)-heptenal, and the amino acid lysine. The antioxidative activity of compounds1–5 was studied. Oxidative stability was evaluated in refined soybean oil containing compounds1–5, butylated hydroxytoluene (BHT),n-propyl gallate orl-lysine, at concentrations of 50–200 ppm. Oils were either oxidized at 60°C and oxidation products determined by the thiobarbituric acid-reactive substances assay, or they were oxidized at 110°C by the Rancimat method. Although both methods gave similar results, greater differences were observed at 60°C than at 110°C. Addition of compounds1–5,l-lysine, BHT, and propyl gallate significantly (P<0.01) protected the oil against oxidation. The effectiveness order found was:l-lysine << compounds3–4 < compounds1–2 < compound5 ≈ BHT << propyl gallate.     

Volatile emerging contaminants in melon fruits,analysed by HS-SPME-GC-MS

The aim of this research was to develop and validate a headspace-solid phase micro-extraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) method for the determination of volatile emerging contaminants in fruit. The method showed good precision (RSD ≤ 14%) and satisfactory recoveries (99.1–101.7%) and LOD and LOQ values ranging between 0.011–0.033 μg kg^?1 and 0.037–0.098 μg kg^?1, respectively. The method was applied to investigate the content of volatile emerging contaminants in two varieties of melon fruit (Cucumis melo L.) cultivated adjoining high-risk areas. Glycol ethers, BHT, BHA and BTEX (benzene, toluene, ethylbenzene and xylene) were determined in melon fruit pulps for the first time, with different sensitivities depending on sample and variety. Although the amount of the volatile contaminants in the melon samples were in the order of µg kg^?1, the safety of vegetable crops cultivated near risk areas should be more widely considered. The results showed that this accurate and reproducible method can be useful for routine safety control of fruits and vegetables.     

Determination of synthetic phenolic antioxidants in soft drinks by stir-bar sorptive extraction coupled to gas chromatography-mass spectrometry

The synthetic phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were pre-concentrated by stir-bar sorptive extraction and thermally desorbed (SBSE-TD) before analysis by GC-MS. Several parameters affecting the derivatisation step and both SBSE extraction and thermal desorption were carefully optimised. When the analyses of BHA and TBHQ in their acetylated, silylated and underivatised forms were compared, the best results were obtained when the in-situ derivatisation procedure with acetic anhydride was employed. Quantification was carried out using carvacrol as the internal standard, providing quantification limits of between 0.11 and 0.15 ng ml^?1, depending on the compound. Recovery assays for samples spiked at two concentration levels, 1 and 5 ng ml^?1, provided recoveries in the 81–117% range. The proposed method was applied in the analysis canned soft drinks and the analytes were found in five of the 10 samples analysed.     

新型抗氧化剂芝麻酚抗氧化活性研究

以油脂过氧化值(POV)为指标,研究合成芝麻酚的抗氧化活性。于底物油样中分别添加不同量的芝麻酚,60℃恒温保存,考察底物过氧化值的变化;同时以相同浓度的PG和BHT作对照,对芝麻酚、PG和BHT三者的抗氧化效果进行了比较。结果显示,合成芝麻酚对植物油花生油和动物油猪油均表现出了良好的抗氧化活性,且其抗氧化活性介于BHT和PG之间。     

气相色谱法测定食用油中BHA和BHT残留量的对比研究

目的建立气相色谱法测定食用油中叔丁基羟基茴香醚(butyl hydroxyanisole,BHA)和二丁基羟基甲苯(butylated hydroxytoluene,BHT)的残留量。方法使用无水乙醇萃取样品,经中性氧化铝吸附杂质,HP-5毛细管柱分离,使用气相色谱仪定量分析BHA和BHT在食用油中的残留量。同时,与GB/T 5009.30中的方法进行对比,考察了本方法的线性、重现性、回收率和精密度。结果本方法中BHA和BHT的线性范围分别为2.02~40.48 ng和2.07~41.36 ng,标准曲线方程分别为Y=16.61X+10.03(r=0.9996)和Y=20.14X+16.56(r=0.9997);BHA和BHT的检出限分别为92.4 ng/kg和108.6 ng/kg,加标回收率分别为98.94%(相对标准偏差为0.33%)、98.69%(相对标准偏差为0.34%)。结论本实验建立的方法灵敏度高、定量准确,和国标法相比,具有简单实用的特点,适合食用油中BHA和BHT残留量的检测。     

凝胶渗透色谱-气相色谱法测定食品中BHA、BHT

建立了凝胶渗透色谱-气相色谱法测定油炸食品中丁基羟基茴香醚(BHA)和二丁基羟基甲苯(BHT)两种抗氧化剂。采用乙酸乙酯-环己烷(体积比为1∶1)溶液提取样品中BHA和BHT。提取液经凝胶渗透色谱(GPC)净化。采用配有FID检测器的气相色谱进行测定。方法准确度高、稳定性好。加标回收率为85.7%~94.0%。BHA和BHT检出限为0.002 mg/m L。BHA和BHT在5 mg/L~100 mg/L时,线性相关系数在0.999 6以上。     

咪唑类离子液体催化合成抗氧剂BHT

2,6-二叔丁基对甲酚（BHT）是一种受阻酚类抗氧化剂,因其抗氧化性强、挥发性低、稳定性高、耐用性好等优点被广泛应用于化工、食品、医药等领域。本文以对甲酚和异丁烯为原料,对咪唑类离子液体1-（3-磺酸基丙基）-3-甲基咪唑（IL1）催化合成BHT的反应进行了研究,得到的最优反应条件为：对甲酚与催化剂IL1的摩尔比为5：1,在80℃下反应8h。BHT粗品的含量达到99.1%,收率为93.0%,且IL1重复使用4次后仍具有较高的催化活性。与传统酸性催化剂如浓硫酸和对甲苯磺酸比较,IL1具有催化活性高、易于分离、可重复使用、对设备腐蚀性小等优点,在BHT的工业制备中具有良好的应用前景。