“水解植物蛋白液+葡萄糖”模型热反应中3-氯-1,2-丙二醇的研究

目的通过设计"水解植物蛋白液+葡萄糖"热反应模型,并结合气质联机对模型热反应中生成的3-氯-1,2-丙二醇(3-MCPD)的含量进行分析。方法通过单因素实验考察不同3-MCPD含量的水解植物蛋白(HVP)液、葡萄糖用量、反应温度、反应时间等因素对模型热反应产物中3-MCPD含量的影响,并初步探究3-MCPD的生成规律。结果模型热反应产物中3-MCPD含量随着HVP液中3-MCPD的含量增加而增加;随着葡萄糖用量增加而减少;随着反应温度的升高,3-MCPD的量先增加后减少,在100℃达到最大,120℃开始减少,140℃急剧减少;在一定的时间范围内,3-MCPD的生成量随着反应时间的增加而升高。结论该热反应模型的构建,对3-MCPD的生成规律探究有一定的价值,为实际生产中减少3-MCPD的含量具有指导作用。     

甘油三酯与氯化钠模型反应中3-氯-1,2-丙二醇的形成研究

主要采用气相色谱-质谱联用技术,通过对在热反应条件下的甘油三酯与氯化钠模型反应产物中的3-氯-1,2-丙二醇（3-chloro-1,2-propanediol,3-MCPD）含量进行分析,探讨其形成机理,并对物料类别、物料配比、反应时间、反应温度等影响因素进行了研究。结果表明：温度升高可急剧增加3-MCPD的含量;高质量分数NaCl可抑制3-MCPD的生成;油酸甘油酯用量增大会促进3-MCPD的生成;硬脂酸甘油酯用量对3-MCPD含量影响不大,原因可能与水解难易程度相关;反应时间对3-MCPD含量的影响较复杂,油酸甘油酯模型中3-MCPD含量随时间延长先增大后减小,再增大,而硬脂酸甘油酯则是先减小后增大,再减小;油酸甘油酯模型中3-MCPD的含量整体上高于硬脂酸甘油酯。     

甘油与氯化钠模型热反应中生成3-氯-1,2-丙二醇的研究

以甘油、氯化钠、水为原料建立热反应模型,结合气相色谱-质谱法(gas chromatography-mass spectrometry,GC-MS)分析,对其生成的3-氯-1,2-丙二醇(3-MCPD)进行了研究.通过正交实验,考察了反应时间、温度和各原料用量对3-MCPD生成量的影响,同时研究了在热反应模型中分别加入不同种类单糖和氨基酸后3-MCPD生成量的变化规律,并对其反应机理进行了探讨.结果表明,反应时间2h、反应温度140℃、甘油用量0.05g(占原料总量0.31％)、NaCl用量1.0g(6.23％)、水用量15g(93.46％),3-MCPD生成量最少;葡萄糖、果糖、木糖、甘露糖、半乳糖、缬氨酸、精氨酸、赖氨酸、丝氨酸、亮氨酸、苯丙氨酸、苏氨酸、组氨酸使3-MCPD的生成量减少;谷氨酸、蛋氨酸、丙氨酸、天冬氨酸、甘氨酸使3-MCPD的生成量增加;半胱氨酸、酪氨酸、脯氨酸、色氨酸对3-MCPD的生成无明显作用.     

单糖与氯化钠模型反应中3-氯-1,2-丙二醇的形成

以"单糖+氯化钠+水"为模型进行热反应,研究3-氯-1,2-丙二醇(3-monochloropropane-1,2-diol,3-MCPD)的形成机理和消长规律。结果表明,在"葡萄糖+氯化钠+水"模型反应中,反应温度对3-MCPD的形成影响最大,其次是氯化钠添加量、反应时间和葡萄糖添加量;在"单糖+氯化钠+水"模型中,6种单糖都生成了3-MCPD,其中核糖和氯化钠反应生成的3-MCPD量最大(30.604μg/kg),果糖生成的量最小(2.498 6μg/kg);在"葡萄糖+氯化钠+水"模型中,反应后生成的挥发性成分5-羟甲基糠醛含量最大,然后是糠醛和2,5-二甲酰基呋喃。根据实验结果探讨3-MCPD的形成机理,提出在单糖模型反应中缩水甘油可能是关键的中间体。     

非氨基酸源因素对热反应牛肉香精中氯丙醇形成的影响

研究肉味香精中非氨基酸源因素(油脂、氯化钠、时间、温度、木糖、牛油、葡萄糖、复合料和pH)对3-MCPD生成量的影响。首先采用气相色谱-质谱联用技术对市场上肉味香精中3-MCPD的含量进行抽样检测,然后建立模型热反应;通过单因素试验研究非氨基酸源对3-MCPD生成的影响,结果表明:在抽检的两个公司中,膏状肉味香精中的3-MCPD含量多于粉状香精;模型热反应牛肉香精中3-MCPD的含量受油脂、氯化钠、时间、温度、木糖和牛油的影响较大,而其它3个因素(葡萄糖、复合料和pH)对3-MCPD的生成量影响不大。     

食用油与氯化钠模型反应中氯丙醇酯的消长规律

为研究热加工过程中食用油与NaCl反应产生3-氯-1,2-丙二醇酯(3-monochloropropane-1,2-diol ester,3-MCPD酯)和2-氯-1,3-丙二醇酯(2-monochloropropane-1,3-diol ester,2-MCPD酯)的变化规律,分别建立食品和煎炸油2个体系模型,考察食用油种类、NaCl含量、反应温度、反应时间、含水量和pH值等因素对2-MCPD酯和3-MCPD酯的含量影响。结果表明:2种模型反应中,食用油种类、反应时间、反应温度和NaCl含量对2-MCPD酯和3-MCPD酯的含量变化有着较大的影响;通过比较发现,在食品模型中,2-MCPD酯和3-MCPD酯的含量随反应温度的增加(100~190℃)呈现下降趋势,分别下降5%和20%,然而在煎炸油模型中,随反应温度的增加(100~220℃)两者呈现增加趋势,分别增加7倍和8倍。另外,随NaCl含量和反应时间的增加,2个模型反应中的2-MCPD酯和3-MCPD酯的含量变化趋势不完全一致。这说明2-MCPD酯与3-MCPD酯虽然结构近似,但消长规律不同。该研究结果可为有效减少热加工食品中氯丙醇酯的含量提供参考。     

精氨酸与木糖模型热反应中3-氯-1,2-丙二醇的形成研究

以精氨酸、木糖、氯化钠、去离子水为原料建立热反应模型,采用气相色谱-质谱仪对其生成的3-氯-1,2-丙二醇进行分析;通过单因素试验,考察热反应时间、温度、配料比、p H值因素对3-氯-1,2-丙二醇生成量的影响,并探讨其反应机理。研究结果表明,"精氨酸+木糖+氯化钠+水"热反应模型能生成3-氯-1,2-丙二醇;热反应产物中3-氯-1,2-丙二醇的含量随着精氨酸含量的增加而减少,随着木糖含量的增加而增加,随热反应时间的延长,总体呈增加趋势;随着Na Cl浓度的增加,3-氯-1,2-丙二醇的生成量先增加后减少再增加;热反应温度上升,3-氯-1,2-丙二醇的含量先减少后增加;p H值逐渐增大,3-氯-1,2-丙二醇含量先增加后减少。     

氨基酸源对热反应牛肉香精中氯丙醇形成的影响

采用气相色谱-质谱联用(gas chromatography-mass spectrometry,GC-MS)仪对热反应牛肉香精及其原料中的氯丙醇进行了分析,并通过单因素试验考察了水解植物蛋白(hydrolyzed vegetable protein,HVP)液、酵母浸膏、VB1、牛肉酶解物、半胱氨酸、谷氨酸、牛骨素、甘氨酸和丙氨酸等原料对热反应牛肉香精中3-氯-1,2-丙二醇(3-chloro-1,2-propanediol,3-MCPD)生成的影响。结果发现,4种氯丙醇中3-MCPD是牛肉香精的主要污染物,且牛肉香精原料中都含有一定量的3-MCPD;牛肉香精原料中所检测的各种氨基酸源对3-MCPD的含量均有显著影响。     

油脂微波加热模型中3-氯-1,2-丙二醇脂肪酸酯的形成

通过建立油脂微波加热模型,研究不同的油脂微波加热后3-氯-1,2-丙二醇（3-chloropropane-1,2-diol,3-MCPD）脂肪酸酯含量的变化情况以及NaCl溶液、pH值、时间、不连续微波和金属离子等因素对3-MCPD脂肪酸酯形成的影响。结果表明：1）熟榨植物油微波加热后3-MCPD脂肪酸酯含量增加均超过9 mg/kg,远超过其他植物油。2）3-MCPD脂肪酸酯含量随NaCl的质量浓度增加而增加,随NaCl溶液体积分数的增加呈先增加后减少趋势。3）酸性环境促进3-MCPD脂肪酸酯形成。4）微波加热10 min内,3-MCPD脂肪酸酯含量与时间呈正相关。5）微波总时间一定的情况下,不连续微波产生的3-MCPD脂肪酸酯明显少于连续微波。6）金属离子作为催化剂参与活性中间物的形成,能明显地促进3-MCPD脂肪酸酯的形成。上述结果可为食品微波加工处理过程中危害物3-MCPD脂肪酸酯的控制研究提供数据支持。     

(E)-2-庚烯醛对半胱氨酸-木糖体系美拉德反应产物的影响

研究了脂类氧化产物(E)-2-庚烯醛对L-半胱氨酸与D-木糖组成的美拉德反应体系热反应产物的影响。加入(E)-2-庚烯醛时,热反应产物在294 nm和420 nm处的吸光值均增大。采用固相微萃取结合气质联用法对不同模型体系热反应挥发性产物进行分析,结果表明,添加(E)-2-庚烯醛的美拉德反应产物中含氮、含硫化合物的形成受到抑制,一些硫醇类、噻吩类、噻唑类等硫化物的含量都有一定程度的减少,尤其是2-甲基-3-呋喃硫醇、2-糠硫醇、3-甲基噻吩和2,5-噻吩二甲醛的含量明显下降。随着(E)-2-庚烯醛含量的增加,生成了一些新的烷基噻吩类,如2-己基噻吩、2-(1,1-二甲基乙基)-噻吩和5-甲基-2-噻吩甲醛等。并且与对照相比,加入(E)-2-庚烯醛的体系新增了一些的醇类、酮类和酯类物质。     

Occurrence of chloropropanols in soy sauce and other foods in China between 2002 and 2004.

A survey of chloropropanols in soy sauce and some selected foods in China is reported. Thirty-seven traditionally brewed soy sauce samples contained 3-MCPD below the EC maximum limit (ML) of 0.02 mg kg(-1). All soy sauce samples (629) from retailers contained levels of 3-MCPD ranging between <0.005 (LOQ) and 189 mg kg(-1), and only 12.2% had levels in excess of the Chinese ML of 1.0 mg kg(-1) for acid hydrolyzed vegetable protein (acid HVP). This indicates that the necessary processing changes have been made to decrease levels of chloropropanols in soy sauce. 2-Monochloropropane-1,3-diol (2-MCPD), 1,3-dichloro-2-propanol (1,3-DCP) and 2,3-dichloro-1-propanol (2,3-DCP) were detected in 48.1 19.1 and 3.78% of the soy sauce samples, respectively; the highest levels being 20.3, 8.26 and 0.50 mg kg(-1), respectively. A good linear correlation was found between the amount of 3-MCPD and 2-MCPD, with the level of 3-MCPD being generally higher than that of other chloropropanols for the same soy sauce. Acid HVP contained 3-MCPD at a level of 0.010-117.7 mg kg(-1) (on a liquid basis) and 80% of samples contained levels exceeding 1.0 mg kg(-1). In some other foods investigated, relatively high levels of 3-MCPD were found in soy sauce powder, oyster sauce, beef products, instant noodle spices and health foods, ranging from 0.029 to 13.64 mg kg(-1). It is concluded that abnormal levels of 3-MCPD in soy sauce or other foods produced in China may result from acid hydrolysis or the addition of the contaminated acid HVP.     

我国市售水解蛋白氯丙醇污染状况研究

采用基质固相分散萃取法(MSPD)进行样品的净化,以稳定性同位素稀释技术结合气相-质谱法(GC-MS)的内标法定量测定氯丙醇,初步调查了我国市售水解蛋白(HVP)氯丙醇的污染水平。发现酸水解HVP产品氯丙醇污染严重,氯丙醇的典型代表3-氯-1,2-丙二醇(3-MCPD)的几何均数达到6.04mg/kg(以液体计),70%的样品3-MCPD含量超过10mg/kg。     

Formation of 3-chloropropane-1,2-diol in systems simulating processed foods

Formation of 3-chloropropane-1,2-diol (3-MCPD) from the precursors glycerol, triolein and soy lecithin in the presence of sodium chloride was studied. The precursors were reacted with sodium chloride in an emulsion stabilised with an emulsifier under conditions which modelled the thermal treatment of foods during processing. Three sets of experiments were carried out aimed to monitor the influence of various factors (NaCl, water content and temperature) on the yield of 3-MCPD. The formation of 3-MCPD strongly depended on the concentration of NaCl and reached a maximum level at about 4–7% NaCl. The highest amount of 3-MCPD was formed in media containing approximately 13–17% water. The amount of 3-MCPD increased with increasing temperature over the range 100–230 °C and reached its highest value at 230 °C. The production of 3-MCPD was also followed in models very closely related to selected foods which had been shown to have a high potential to yield 3-MCPD during processing (salami, beefburgers, processed cheese, biscuits, crackers, doughnuts). The highest levels of 3-MCPD were formed in models simulating salami as they had the highest content of both fat and salt of all the samples. The lowest amount of 3-MCPD was formed in the models simulating biscuits and crackers as they had a low salt content and, at the same time, their water content was below the optimum level.     

Effects of temperature and water content on the formation of 3-chloropropane-1,2-diol fatty acid esters in palm oil under conditions simulating deep fat frying

The influence of NaCl addition, water content, heating temperature and heating time on the formation of 3-chloropropane-1,2-diol fatty acid esters (3-MCPD esters) in palm oil simulating deep fat frying was examined in this study. The results in our study showed that all those four factors had significant effects on the generation of 3-MCPD esters in palm oil during deep fat frying. There was a significant increase in the content of 3-MCPD esters formed in palm oil when heating time was 2 h. The effect of water content was the most evident in 3-MCPD esters formation. The heating process imparted an accretion of up to 130 % from 1,260 to 2,950 mg/kg with increasing the water dosage from 7 to 10 %. In addition, 3-MCPD esters were decomposed when heated at high temperatures for a long time (longer than 2 h).     

Influence of composition,moisture, pH and temperature on the formation and decay kinetics of monochloropropanediols in wheat flour dough

A study of the formation and decay kinetics of 3-chloropropane-1,2-diol (3-MCPD) and 2-chloropropane-1,3-diol (2-MCPD) in model dough systems is reported. The influence of ingredient composition, moisture, pH and temperature were assessed. It was shown that white flour, salt and water alone were sufficient to generate 2-MCPD and 3-MCPD. The formation of 3-MCPD agreed with zero order kinetics and occurred most readily in dry, full recipe dough; below 15%, the exact moisture content was not critical. The formation of 2-MCPD followed that of 3-MCPD but at approximately one fifth of the rate, irrespective of dough type. The decay of 3-MCPD was consistent with first order kinetics and the overall rate in dough was slower than that in pure water. The decay reaction was inhibited by a decrease in moisture content and a drop in pH seen at high temperatures in the cereal systems investigated. One of the products of 3-MCPD decay in dough was 2-chloropropane-1,3-diol (2-MCPD). Data obtained from the model system studies showed good agreement with 3-MCPD levels formed in real foods. Possible mechanisms of decay and formation in dough are discussed.     

Effects of yeast stress and pH on 3-monochloropropanediol (3-MCPD)-producing reactions in model dough systems

A major precursor of 3-monochloropropanediol (3-MCPD) in leavened cereal products is glycerol, which is formed as a natural by-product of yeast fermentation. However, yeast metabolism is affected by stresses such as low osmotic pressure from, for example, the incorporation of sugar or salt in the dough recipe. Tests with model doughs have shown that glycerol production was proportional to yeast mass and limited by available sugars, but that high levels of yeast inhibited 3-MCPD formation. The yeast fraction responsible for the inhibition of 3-MCPD in model dough was shown to be the soluble cytosol proteins, and the inhibition mechanism could be explained by the known reactions of 3-MCPD and/or its precursors with ammonia/amino acids (from yeast proteins). Added glucose did not increase the production of glycerol by yeast but it did promote the generation of 3-MCPD in cooked doughs. The latter effect was attributed to the removal of 3-MCPD inhibitors such as ammonia and amino acids by their reactions with added glucose (e.g. Maillard). The thermal generation of organic acids from added glucose also reduced the pH of cooked doughs, so the effect of pH and short-chain organic acids on 3-MCPD generation in dough was measured. There was a good correlation between initial dough pH and the level of 3-MCPD generated. The effect was weaker than that predicted by simple kinetic modelling, suggesting that the involvement of H⁺ and/or the organic acid was catalytic. The results showed that modifications to dough recipes involving the addition of reducing sugars and/or organic acids can have a significant impact on 3-MPCD generation in bakery products.