抗坏血酸产生呋喃的基础研究模型的建立

通过建立抗坏血酸基础研究模型,利用顶空气相色谱-质谱法检测其生成的呋喃,研究了pH、加热温度及加热时间对抗坏血酸生成呋喃的影响。结果发现,抗坏血酸能产生呋喃,pH、加热温度及加热时间在抗坏血酸形成呋喃的过程中均起到非常重要的作用。加热温度不超过90℃,抗坏血酸几乎不产生呋喃,pH对抗坏血酸产生呋喃几乎没有什么影响,但加热温度超过90℃,pH对其产生呋喃就有明显不同的作用;而且,在热加工过程中,抗坏血酸在酸性条件下产生的呋喃含量最高,在碱性体系下生成的呋喃含量最低。另外,加热时间越长,抗坏血酸产生的呋喃的量就会越多。这些结果为实际食品生产中减少呋喃产生提供了重要的理论依据。     

高暴露水平的大豆热加工食品体系中呋喃产生及其控制

呋喃是国际社会关注的食品污染物之一,目前对它的形成途径及形成机制并不完全清楚。选取呋喃高暴露水平的豆奶粉、豆豉作为研究体系,在实验室小试的水平上,模拟这2种大豆加工食品的生产工艺,通过组分的逐步添加与工艺的改变找出影响这2种大豆热加工食品生产过程中呋喃产生的关键因素。结果表明:豆豉加工过程中,蒸煮、发酵及糖、调味粉和植物油的添加能够显著影响豆豉中呋喃的含量,蒸煮与发酵72 h过程中产生的呋喃危害物分别为(91.27±4.21)、(102.29±5.02)ng/g,分别为浸泡过程的6.2倍和6.9倍,而实际加工过程中可以控制蒸煮时间和发酵时间达到减少呋喃产生,另外还可以将豆豉制成干样,从而降低因加工过程产生的呋喃;豆奶粉加工过程中,灭酶、均质和喷雾干燥是呋喃产生的关键步骤,产生的呋喃分别为(71.40±3.87)、(97.83±4.98)、(355.18±156.87)ng/g,分别为烘干脱皮过程的4.2倍、5.82倍和24.0倍。实验结果为优化豆豉和豆奶粉加工工艺,抑制呋喃的形成提供理论参考和技术支持。     

氨基酸对葡萄糖、半乳糖模型产生呋喃的影响

为研究氨基酸对葡萄糖和半乳糖模型产生呋喃的影响,通过向葡萄糖模型和半乳糖模型中加入不同含量的甘氨酸、丝氨酸、苏氨酸、谷氨酸,模拟密封罐装食品的灭菌条件（121 ℃条件下油浴30 min）,采用顶空气相色谱-质谱（headspace-gas chromatography-mass spectrometry,HS-GC-MS）法检测呋喃的含量。结果表明：低含量（≤5 mg）的甘氨酸、极低含量（1 mg）的丝氨酸、高含量（50 mg）的苏氨酸和谷氨酸的添加能够明显促进葡萄糖模型产生呋喃,而对于半乳糖模型,所有高含量（50 mg）氨基酸的添加都能够导致呋喃的大量产生。苏氨酸对葡萄糖模型产生呋喃的促进作用明显强于其余3 种氨基酸（P＜0.05）;对于半乳糖模型,甘氨酸、苏氨酸对其产生呋喃的促进作用最强,且它们之间无明显差异。     

食源性柚皮苷抗氧化性及其对呋喃所致小鼠肝肾损伤的保护作用

呋喃是食品热加工过程中产生的对人体有害的典型食品污染物。本研究以呋喃为对象,探讨食源性柚皮苷的抗氧化性及其对呋喃毒性的影响。50只雄性BALB/C小鼠随机分为5组,即对照组、呋喃染毒组(16 mg/kg/d)、柚皮苷保护组(5,10,20 mg/kg/d),通过评价小鼠体内细胞活性氧(ROS)含量、氧化损伤、细胞因子水平、DNA损伤及肝肾损伤情况,结合食源性柚皮苷的体外抗氧化活性研究柚皮苷对呋喃所致毒性的保护作用。结果表明:呋喃染毒对小鼠的肾脏和肝脏造成不同程度的损伤,与呋喃染毒组相比,一方面,柚皮苷通过提升GST、GSH以及SOD活性,降低MPO和MDA含量减轻呋喃所致小鼠的氧化损伤;另一方面,柚皮苷能降低细胞因子IL-1β、IL-6、IL-10和TNF-α的含量;同时,柚皮苷可以降低ROS,DNA损伤指标8-OHdG,肝损伤指标AST,肾损伤指标ALT、LDH、BUN和肌酐含量。结论:食源性柚皮苷作为抗氧化剂对呋喃所致小鼠肝肾损伤具有一定的保护作用,其中10 mg/kg/d柚皮苷保护组的保护作用最好。     

三种常见糖类产生呋喃的影响因素研究

通过利用顶空气相色谱-质谱法检测葡萄糖、果糖和蔗糖反应模型生成呋喃的方法,研究了pH、加热温度及加热时间对糖类生成呋喃的影响。结果发现,葡萄糖、果糖和蔗糖在加热模式下均可产生一定量的呋喃,pH、加热温度及加热时间在糖类形成呋喃的过程中均起到非常重要的作用。葡萄糖和果糖在酸性pH下产生的呋喃较少,相反,蔗糖在碱性条件下产生的呋喃较少;而对于葡萄糖和果糖而言,加热温度不超过90℃,pH对其产生呋喃几乎没有什么影响,但加热温度超过90℃,pH对其产生呋喃就有明显不同的作用;蔗糖在高于130℃下才会产生呋喃,而果糖和葡萄糖加热温度在90℃左右便会产生呋喃;另外,加热时间越长,葡萄糖、果糖和蔗糖产生的呋喃的量就会越多。而在实际食品体系生产中,这些结果可以为优化加工工艺,抑制呋喃的产生提供理论参考。     

烘焙时间对云南小粒咖啡挥发性成分影响的研究

本文研究了云南小粒咖啡在烘焙过程中挥发性成分及含量的变化。在230℃烘焙温度条件下,对不同烘焙时间的小粒咖啡采样,采用两种方法对样品进行分析:一、同时蒸馏萃取法提取挥发性成分,采用了气相色谱-质谱联用仪对云南小粒咖啡中的挥发性成分进行了分析检测;二、顶空直接进样,气相色谱-质谱联用仪进行分析检测。对数据进行了定性定量分析、以及聚类分析。方法一分析了160种挥发性化合物,方法二分析了15种挥发性化合物。从数据可以看出,咖啡在此温度条件下,烘焙6 min后,咖啡的主要挥发性成分已经产生,如:2-甲基吡嗪、糠醇、5-甲基呋喃醛、2-乙基-5-甲基吡嗪等。随着烘焙时间增加,咖啡中的挥发性成分种类及含量变化明显。经过聚类分析可以看出,可以分为4类,可以作为判别咖啡烘焙程度一个方法。     

灭菌过程中乳糖-氨基酸模型生成呋喃的影响因素研究

呋喃是一种"2B"类致癌物,可由维生素C、碳水化合物、氨基酸、多不饱和脂肪酸和类胡萝卜素等多种前体合成,广泛存在于热加工食品中。呋喃的危害在婴幼儿食品中更为严重,为此本文基于婴幼儿金枪鱼泥中游离糖类和氨基酸类的成分及含量,构建了四种乳糖-氨基酸模型,设计了二水平部分因子实验,系统地研究了灭菌时间、灭菌温度、p H值、相态和缓冲体系对呋喃形成的影响。结果表明:在四种乳糖-氨基酸模型中,各因素对呋喃的影响有相似的规律,即高温、长时间加热、中性环境、液态和磷酸盐促进呋喃的形成;灭菌时间、灭菌温度、p H值、缓冲体系对呋喃生成量的影响较大,而相态的影响效果较小。本研究旨在为食品中呋喃的防控提供一定的理论基础,同时也为食品中其它危害物的研究提供方法借鉴。     

焦糖色素的增香功能

<正> 20世纪生产的焦糖色素中,大部分被用作着色,仅有极少部分被作为增强香味之用。D.D.Williamson公司研究焦糖色素在速溶咖啡中的应用发现,焦糖色素非但改善了产品的色泽,还增强了其香味。在进一步的定性分析下,从焦糖色素中鉴定出两个咖啡香味的主要成分:糠醛(2-氧基-2甲基呋喃)和糠醇(2-羟甲基呋喃)。研究数据还证实,在咖啡中加入少量(5％)焦糖色素,将大大增加最终产品中这两种成分的含量。     

多次顶空萃取-选择离子流动管-质谱法测定食用油中呋喃的气液分配系数

呋喃属于食品热加工过程中产生的潜在致癌物。为准确测定呋喃在食用油中的气液分配系数,采用多次顶空萃取-选择离子流管-质谱法测定封闭体系顶空中的呋喃含量,并根据分配系数定义和多次顶空萃取过程,建立了测定油中呋喃分配系数的数学关系式。结果表明,澳洲坚果油、大豆油、花生油、橄榄油中呋喃的分配系数为338.5、336.4、357.6、365.6(60℃时)。该方法具有良好的精密度(RSD6.1%)和准确度,且简单、实用、不需要呋喃标样,所获得的数学关系式可作为其他挥发性成分分配系数测定的参考。     

葡萄糖氧化酶对模拟热加工食品中呋喃生成量的抑制作用研究

呋喃是食品热加工的产物之一,会损伤肝肾,并且已经被列为Ⅱ类致癌物,因此探究呋喃在食品热加工过程中的生成规律并且研究调控其生成量具有重要意义。以葡萄糖与丙氨酸、甘氨酸模拟体系研究食品热加工过程中发生的美拉德反应,通过向模拟体系中添加葡萄糖氧化酶,研究不同反应条件对呋喃生成的影响。结果表明:在酶解温度为50℃,时间为40 min,葡萄糖-丙氨酸模拟体系和葡萄糖-甘氨酸模拟体系中酶的添加量分别为3000、4000 U/mg时,对呋喃的抑制率分别为80.79%和78.68%。通过响应面优化,在葡萄糖-丙氨酸模拟体系中,酶解温度为57.8℃,时间为45.6 min,酶添加量为3254 U/mg时,对呋喃的抑制可达83.63%。而在葡萄糖-甘氨酸模拟体系中,酶解温度为57.9℃,时间为45.7 min,酶添加量为4252 U/mg时,对呋喃的抑制率可达81.02%。研究为日后调控呋喃在食品热加工过程中的生成量提供基础。     

Furan in coffee: pilot studies on formation during roasting and losses during production steps and consumer handling

The occurrence of furan in some food products has already been known for a few decades, and it has been reconfirmed in more recent investigations that furan is present in a variety of foodstuffs. This list of products includes roasted coffee, which has been shown to generate furan as a result of the heat treatment at roasting which is applied to achieve the desired aroma and flavour profile of a roasted coffee. The objective of this study is to provide data to allow a better understanding of the available data of furan in coffee, the kinetics of furan generated during roasting, and to estimate the reduction of furan levels afterwards due to subsequent processing steps and consumer handling. Finally, the study is meant as a contribution to establish exposure data on the basis of scientific data at the stage of coffee consumption. This paper shows that the formation of furan during roasting is dependent on roasting conditions and is, therefore, directly linked to achieving targeted flavour profiles. Furthermore, it is demonstrated that modifications in process conditions potentially to reduce furan levels may have the opposite effect on other undesired reaction products of the roasting chemistry such as, for example, acrylamide. Due to the high volatility of furan, any subsequent processing step or consumer handling has an impact on the level of furan. As a guidance from this study and in consideration of the identified losses of each process and handling step on the basis of the trial conditions, it is estimated that only approximately 10% of the initially generated furan during roasting gets into the cup of coffee for consumption.     

Tea Polyphenols as Inhibitors of Furan Formed in the Maillard Model System and Canned Coffee Model

In this article, the effects of sugars and amino acids on furan formation via the Maillard reaction in low‐moisture model systems were investigated. Glucose and alanine are important furan precursors, and the effects of the heating temperature, heating time, and molar ratio of glucose to alanine on furan formation were studied in glucose/alanine model system by response surface methodology. The heating temperature greatly affected furan formation. The maximum furan concentration was obtained with a glucose‐to‐alanine molar ratio of 0.83:1.00, by heating at 151 °C for 41 min. Tea polyphenols effectively inhibited furan formation in the glucose/alanine model and a canned coffee model. A high inhibition rate of 42.4% ± 1.5% was obtained in the canned coffee model during sterilization procedure with addition of 84 mg (the mass fraction is 12.1%) of tea polyphenols (99%). However, the content of aromatic components in the canned coffee model was significantly reduced at the same time. This study provides evidence for a good furan inhibitor that can be used in food processing.     

Survey of furan in foods and coffees from five European Union countries

Canned and jarred baby foods (74), canned and jarred adult foods (63) and 70 coffees sold in Belgium, Italy, Portugal, Spain and The Netherlands were analysed for their furan content using a validated automated headspace GC–MS procedure. Seven balsamic vinegars from Italy and Spain were also analysed. All 74 baby food samples contained detectable furan, with an average level of 37 ng/g. A total of 54 of 63 canned and jarred foods contained detectable furan with an average level of 24 ng/g. Levels of furan in coffee as consumed were very variable and reflected different preparation methods and coffee strengths. Over 50% of Italian samples contained more than 200 ng/g, whereas over 20% of Belgian coffees contained less than 21 ng/g furan. Some brews made from fine grained coffee contained much more furan than did brews made from normal or coarse grained coffee. Although furan was low in most instant coffees, two Italian products “instant espresso” and “instant mocha” contained about 150 ng/g furan. Balsamic vinegars from Spain contained 159–662 ng/g of furan; however, other samples from Spain and Italy contained only 6–25 ng/g.     

Analysis of furan in foods. Is headspace sampling a fit-for-purpose technique?

Headspace GC-MS has been opitimized for the determination of furan in foods. The conditions of sample preparation, headspace sampling and GC separation were optimized to enhance sensitivity during GC-MS analysis. Green coffee was used to prepare a matrix matched calibration curve for furan. However, it was unexpectedly found that a green coffee sample was not blank. GC-MS analysis performed after equilibration for 30 min at 40°C showed the presence of 4.2 ng/g furan in green coffee. In order to understand whether furan was naturally present or formed during headspace sampling, green coffee was investigated in time-dependent manner at headspace equilibration temperatures of 40 and 70°C. It was observed that furan response continued to increase in a way similar to first order formation kinetics. The same behavior was found for freshly squeezed tomato and orange juices leading to the suspicion of furan formation during headspace equilibration. It is concluded that a matrix matched calibration for each particular food matrix is necessary to compensate for furan formation during headspace sampling, and thus, to quantify furan more accurately.     

A comprehensive review of furan in foods: From dietary exposures and in vivo metabolism to mitigation measures

Furan is a thermal food processing contaminant that is ubiquitous in various food products such as coffee, canned and jarred foods, and cereals. A comprehensive summary of research progress on furan is presented in this review, including discussion of (i) formation pathways, (ii) occurrence and dietary exposures, (iii) analytical techniques, (iv) toxicities, (v) metabolism and metabolites, (vi) risk assessment, (vii) potential biomarkers, and (viii) mitigation measures. Dietary exposure to furan varies among different countries and age groups. Furan acts through various toxicological pathways mediated by its primary metabolite, cis-2-butene-1,4-dial (BDA). BDA can readily react with glutathione, amino acids, biogenic amines, or nucleotides to form corresponding metabolites, some of which have been proposed as potential biomarkers of exposure to furan. Present risk assessment of furan mainly employed the margin of exposure approach. Given the widespread occurrence of furan in foods and its harmful health effects, mitigating furan levels in foods or exploring potential dietary supplements to protect against furan toxicity is necessary for the benefit of food safety and public health.     

Furan in heat‐treated foods: Formation,exposure, toxicity,and aspects of risk assessment

Furan is formed in a variety of heat‐treated foods through thermal degradation of natural food constituents. Relatively high levels of furan contamination are found in ground roasted coffee, instant coffee, and processed baby foods. European exposure estimates suggest that mean dietary exposure to furan may be as high as 1.23 and 1.01 μg/kg bw/day for adults and 3‐ to 12‐month‐old infants, respectively. Furan is a potent hepatotoxin and hepatocarcinogen in rodents, causing hepatocellular adenomas and carcinomas in rats and mice, and high incidences of cholangiocarcinomas in rats at doses ≥2 mg/kg bw. There is therefore a relatively low margin of exposure between estimated human exposure and doses that cause a high tumor incidence in rodents. Since a genotoxic mode of action cannot be excluded for furan‐induced tumor formation, the present exposures may indicate a risk to human health and need for mitigation. This review summarizes the current knowledge on mechanisms of furan formation in food, human dietary exposure to furan, and furan toxicity, and highlights the need to establish the risk resulting from the genotoxic and carcinogenic properties of furan at doses lower than 2 mg/kg bw.     

Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting

In this work, we evaluated the occurrence of furan in brews obtained from regular, decaffeinated, and instant coffee and commercial packed capsules. For this purpose, a previously developed automated headspace solid-phase microextraction method coupled to gas chromatography–mass spectrometry (HS-SPME-GC–MS) was used. Initially, the influence of HS-SPME conditions on furan formation was evaluated. In addition, the effect of roasting conditions (temperature and time) used for coffee beans on furan formation was also studied. We found that low temperature and long roasting time (140 °C and 20 min) decreases the final furan content. Furan concentrations in regular ground coffee brews from an espresso coffee machine were higher (43–146 ng/ml) than those obtained from a home drip coffee maker (20 and 78 ng/ml), while decaffeinated coffee brews from a home drip coffee maker (14–65 ng/ml) showed a furan concentration similar to that obtained from regular coffee. Relatively low concentrations of this compound (12–35 ng/ml) were found in instant coffee brews, while commercial packed coffee capsules showed the highest concentrations (117–244 ng/ml). Finally, the daily intake of furan through coffee consumption in Barcelona (Spain) (0.03–0.38 μg/kg of body weight) was estimated.     

Estimation of furan contamination across the Belgian food chain

This paper provides an estimate of the furan content of Belgian foods. The objective of the study was to achieve the best food chain coverage with a restricted number of samples (n = 496). The geographic distribution, different market chains and labels, and consumption frequencies were taken into account in the construction of the sampling plan. Weighting factors such as contamination levels, consumption frequency and the diversity of food items were applied to set up the model. The very low detection capabilities (CC(β)) of the analytical methods used (sub-ppb) allowed reporting of 78.2% of the overall dataset above CC(β) and, in particular, 96.7% for the baby food category. The highest furan levels were found in powdered roasted bean coffee (1912 μg kg(-1)) with a mean of 756 μg kg(-1) for this category. Prepared meat, pasta and rice, breakfast cereals, soups, and baby food also showed high mean furan contents ranging from 16 to 43 μg kg(-1). Comparisons with contamination surveys carried out in other countries pointed out differences for the same food group and therefore contamination levels are related to the geographical origin of food items.     

Are Chileans exposed to dietary furan?

Chilean consumer preferences include foods that may contain considerable amounts of furan, a potential human carcinogen. However, there is no information regarding dietary exposure to furan in Chile. Thus, the objective of this work was to determine the Chilean exposure to dietary furan. To accomplish this objective, the furan concentration of 14 types of commercial foods processed at high temperature were analysed based on a modified headspace-GC/MS (HS-GC/MS) method in which the limits of detection for different food matrices ranged from 0.01 to 0.6 ng g^?1. In addition, a risk assessment was made with exposure estimates based on dietary data from national studies on different age groups (9-month-old babies, school children, adults and elderly people). Of the food items surveyed “American”-type coffee (espresso coffee plus hot water) obtained from automatic coffee machine (936 ng g^?1) and low moisture starchy products like crisps and “soda”-type crackers showed the highest furan concentrations (259 and 91 ng g^?1, respectively). Furthermore, furan was also found in samples of breakfast cereals (approximately 20 ng g^?1), jarred fruit baby foods (8.5 ng g^?1) and orange juice (7.0 ng g^?1). School children (aged 9–13 years) represented the highest intake of furan (about 500 ng kg^?1_bw day^?1), with margins of exposure of 2479 and 2411, respectively, which points to a possible public health risk.     

Furan and Methylfurans in Foods: An Update on Occurrence,Mitigation, and Risk Assessment

The acceptance of many foods is related to traditional cooking practices, which create taste and texture and are important to digestibility, preservation, and the reduction of foodborne illnesses. A wide range of compounds are formed during the cooking of foods, a number of these have been shown to lead to adverse effects in classical toxicological models and are known as food processing contaminants (FPC). It is essential that the presence and effects of such compounds alone and in combination within the diet are understood such that proportionate risk management measures can be developed, while taking a holistic view across the whole value chain. Furan and alkylfurans (principally 2‐ and 3‐methylfuran) are highly volatile FPC, which are formed in a wide range of foods at low amounts. The focus of research to‐date has been on those foods, which have been identified to be most consequential in terms of being sources of exposure, namely jarred and canned foods for infants and young children (meals and drinks) and coffee (roast and ground, soluble). This report presents (i) new industry data on the occurrence of furan and methylfurans in selected food categories following previous coffee studies, (ii) the most salient parameters that impact furan formation, and (iii) aspects of importance for the risk assessment.