Frying oils with lower levels of saturated fatty acids induce less heterocyclic amine formation in meat floss (boiled,shredded and fried pork)

Heterocyclic amines (HAs) as potent mutagens are formed in meat floss which is a boiled, shredded and fried traditional meat product. In this study, effects of frying oils (lard, soybean oil and palm oil) on the formation of HAs in meat floss during frying have been investigated. The results showed that the contents of Norharman, Harman, AαC and MeAαC in meat floss that treated with lard and palm oil were higher than soybean oil which contained less saturated fatty acids (P < 0.05). The contents of total HAs in meat floss that treated with palm oil at 150 °C and 180 °C were significantly higher than that treated with soybean oil and lard (P < 0.05). In conclusion, meat floss treated with soybean oil at 120 °C, 150 °C and 180 °C contained lowest levels of HAs and soybean oil could be used as lard substitution to produce healthy meat floss.     

HPLC法检测市售传统肉制品中的杂环胺含量

本文研究了市售传统肉制品中杂环胺的含量,根据加工工艺不同,对肉制品中进行分类研究,应用高效液相色谱法(high performance liquid chromatography)检测市售传统肉制品中杂环胺(Heterocyclic Amines)的种类和含量,从购买来源(个人摊点、超市和专售店)、种类及加工工序(酱卤、油炸-酱卤、酱卤-烤制以及烤制)角度分析传统肉制品中HAs的特点,并分析不同种肉制品基本化学成分。研究表明:不同肉制品中基本成分含量各不相同;个人摊点中HAs含量比超市和专售相对较高;不同加工工序中酱卤-油炸和烤制中HAs的含量相对较高,含量高达13.40 ng/g,并且所有工序中都检测到Norharman和Harman;鸡皮比鸡肉(不带皮)中HAs含量高,酱卤鸡腿、酱卤烧鸡和叫花鸡皮中HAs的含量分别是鸡肉(不带皮)HAs含量的2.8、1.5和1.5倍。     

Antioxidant capacity and inhibitory effect of grape seed and rosemary extract in marinades on the formation of heterocyclic amines in fried beef patties

The effect of oil-based marinades containing grape seed extract (Vitis vinifera L.; 0.2, 0.4, 0.6 and 0.8 g/100 g) formulated in a water/oil emulsion or rosemary extract (Rosmarinus officinalis; 0.12, 0.2, 0.6, 1.0 and 1.5 g/100 g) in oil on the formation of heterocyclic amines (HAs) in fried beef patties was examined. After application of marinades and frying, four HAs MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5b]pyridine), Norharman, and Harman were found at low levels in all fried patties, MeIQx (0.3–1.0 ng/g), and PhIP (0.02–0.3 ng/g). The content of MeIQx and PhIP were significantly reduced by approx. 57% and 90% (p < 0.05), respectively, after use of marinades containing the highest extract concentration. The antioxidant capacity of grape seed was about two-times greater than that of rosemary extract. A correlation between inhibition of HAs and Trolox-equivalents (MeIQx, R² = 0.85, p < 0.001; PhIP, R² = 0.83, p < 0.001) was found. Sensory tests showed a high acceptance of flavour and colour for controls and samples.     

Effects of varying degrees of doneness on the formation of Heterocyclic Aromatic Amines in chicken and beef satay

The study was carried out to determine the effect of cooking method on Heterocyclic Aromatic Amines (HAs) concentration in grilled chicken and beef (satay). Six common HAs were investigated: 2-amino-3-methylimidazo[4,5-f]quinolone (IQ), 2amino 3,4dimethylimidazo [4,5f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8 trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-3,7,8trimethylimidazo [4,5-f]quinoxaline (7,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Chicken and beef satay samples were grilled to medium and well done level of doneness. Charcoal grilled (treatment A), microwave pre-treatment prior to grilling (treatment B), and microwave-deep fried (treatment C) were applied to beef and chicken satay samples. The satay samples which were microwaved prior to grilling (B) showed significantly (p < 0.05) lower HAs concentration as compared to those charcoal grilled (A). Both medium and well done cooked beef and chicken satay samples that were microwaved and deep fried (C) as an alternative method to grilling were proven to produce significantly lesser HAs as compared to charcoal-grilled (A) and microwaved prior to grilling (B).     

Effect of lipid oxidation products on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in model systems

Ternary mixtures of creatinine, phenylalanine and lipids (or carbohydrates) were heated at 200 °C for 1 h to determine the potential contribution of lipids to the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Although unoxidised lipids did not contribute to PhIP formation, their oxidation produced many compounds that significantly increased the formation of PhIP. Among the different lipid oxidation products (LOPs) studied, which included ω-6 and ω-3 derived lipid hydroperoxides, 2,4-alkadienals, 2-alkenals, 4,5-epoxy-2-alkenals, 4-oxo-2-alkenals, and 4-hydroxy-2-nonenal, 4-oxo-2-nonenal was the most reactive compound. It produced 32.48 pmol of PhIP/μmol of creatinine in comparison with the 7.92 pmol of PhIP/μmol of creatinine produced by the control phenylalanine/creatinine reaction mixture. 4-Oxo-2-nonenal reactivity was similar to that of most carbohydrates; although ribose and arabinose produced more PhIP (44–46 pmol of PhIP/μmol of creatinine). In addition to single LOP, the addition of oxidised soybean oil for 24–144 h at 60 °C also increased PhIP formation. All these results pointed out to a potential contribution of LOP to the formation of PhIP in food products. This contribution will depend on the lipid content of the food product and its easiness to be oxidised.     

腐殖酸与多环芳烃结合强度的相关因素研究

研究了具有不同结构特征的腐殖酸与多环芳烃蒽的结合强度与腐殖酸分子中的核心官能团含量及酸度变化的关系。结果表明,腐殖酸溶液与蒽的结合常数KOC与UV254/TOC的变化呈现出很好的相关性;各腐殖酸溶液与多环芳烃蒽的结合常数KOC随酸度的增强而增强。说明腐殖酸与多环芳烃之间作用的核心可能在腐殖酸类物质的苯环上,腐殖酸的酸性基团参与了腐殖酸与多环芳烃之间的作用。     

光催化膜对水中腐植酸的去除及积垢机理

利用湿式相转化方法制备TiO₂/聚苯砜（polyphenylsulfone,PPSU）/聚醚亚硫胺（polyetherimide,PEI）催化膜应用于水中腐植酸（humic acid,HAs）的去除及积垢机理研究。结果表明,随着亲水性PEI比例增加,光催化膜的纯水通量和HAs的过滤通量越大,去除效率越低;且随着光照时间的延长去除效率越趋于稳定,且有回复的现象。在0.2MPa操作压力下,制备的TiO₂/PPSU/PEI （1%/50%/50%）膜具有最佳的可逆阻抗力比例（R_c/R_t=48.24%）;其渗透通量、HAs去除效率及反洗后通量分别为34.0L/（m²·h）、63.2%及22.5L/（m²·h）,具有较佳的通量及HAs去除效率。     

海洋沉积物DNA提取前的简易脱腐方法研究

针对海洋沉积环境样品DNA提取中的腐殖酸去除难题,采取先脱除腐殖酸再提取DNA的策略,进行了海洋沉积物DNA提取前的简易脱腐方法研究.依据腐殖酸的理化性质, 遴选出由Tris-HCl、EDTA、Na4P2O7、NaCl、PVP、Triton X-100及脱脂奶粉组成脱腐缓冲液,有效地脱除了腐殖酸.之后采用温和的溶菌酶-蛋白酶K-SDS直接裂解法,获取了大片段(分子量21kb以上)可进行rpoB 基因PCR扩增的海洋沉积物DNA,为海洋沉积环境分子生态学研究与海洋生物活性物质开发奠定了基础.