The effects of lactate on nitrosylmyoglobin formation from nitrite and metmyoglobin in a cured meat system

Two experiments were conducted to determine the effects of lactate on nitrite during meat curing. In the first experiment, using a model system, eight reaction components including nitrite and lactate, were used to assess the effect of each component on metmyoglobin reducing activity by excluding one component at a time. Excluding lactate, nicotinamide adenine dinucleotide (NAD), l-lactate dehydrogenase (LDH) or phenazine methosulfate (PMS) resulted in no reducing activity. A second experiment, utilising a meat mixture, investigated the effects of lactate (0%, 2%, 4% or 6%), nitrite (0 or 156 ppm), and packaging (oxygen-permeable or vacuum) on residual nitrite, meat colour and pH. Addition of lactate reduced residual nitrite in the meat mixtures. Both experiments support the hypothesis that lactate generates NADH which then reduces metmyoglobin to deoxymyoglobin. The resulting greater concentration of reduced myoglobin subsequently reacted with nitrite to produce more nitric oxide, reducing nitrite concentration and accelerating curing reactions.     

北京市蔬菜硝酸盐和亚硝酸盐污染状况评价

为了解北京市蔬菜中硝酸盐和亚硝酸盐的污染情况 ,于 2 0 0 3年 4月～ 8月从北京 15个菜市场采集应季蔬菜样品 ,共 4 0个品种 4 44份样品 ,用国标法 (GB T 5 0 0 9 33— 2 0 0 3)分析蔬菜中的硝酸盐和亚硝酸盐的含量。结果显示 :检测样品中 ,污染程度严重的占 33 1% ;中、重度污染的占2 3 6 % ;轻度的占 4 3 2 % ;硝酸盐的含量依次为绿叶菜类 >白菜类 >根茎类 >瓜茄类 >葱蒜类 >豆类 >果类 >水生植物类 ,但同一类蔬菜不同品种的硝酸盐的含量差别较大 ,从几倍到几十倍 ;同一品种的蔬菜中硝酸盐含量差别也很大 ,可能与产地、生长条件不同有关。蔬菜中亚硝酸盐含量相对较低 ,其含量与蔬菜的新鲜程度有关。研究结果提示需要制定限量标准 ,加强监督管理     

Relationship between nitrate/nitrite reductase activities in meat associated staphylococci and nitrosylmyoglobin formation in a cured meat model system

Quantitative determination of catalase, nitrate reductase, nitrite reductase and nitric oxide synthase activities (NOS) was performed on 11 different bacterial strains, mainly staphylococci, isolated from fermented sausages, bacon brine or cured meat products. All except one strain possessed catalase activity in the range from 1.0 to 6.1 μmol min^− 1 ml^− 1. Ten out of 11 bacteria strains showed nitrate reductase activity in the range between 50 and 796 nmol min^− 1 ml^− 1 and nine showed nitrite reductase activity in the range between 6 and 42 nmol min^− 1 ml^− 1. No evidence of NOS activity of the selected strains was detected. In a colour formation assay containing myoglobin all strains affected nitrosylmyoglobin (MbFe^IINO) formation in assays containing nitrite, whereas only strains having nitrate reductase activity generated MbFe^IINO in assays containing nitrate as the sole nitrosylating agent. The quantitative nitrate and nitrite reductase activity did not fully explain or correlate well with the observed rate of formation of MbFe^IINO, which seemed to be more affected by the growth rate of the different strains. The mechanism of the reduction of nitrite into NO of strains not having nitrite reductase activity remains to be fully elucidated, but could be due to a dual-mode action of nitrate reductase capable of acting on nitrate.     

国内外肉制品中食品添加剂硝酸盐和亚硝酸盐的标准管理探讨

目的 探讨肉制品中食品添加剂硝酸盐和亚硝酸盐的标准管理.方法 通过对国际食品法典以及美国、加拿大、欧盟、澳新、日本、韩国和中国肉制品中硝酸盐和亚硝酸盐食品添加剂标准规定的分析,结合风险评估、监测结果和食品中毒事件数据分析的情况,探讨相关标准未来的发展方向.结果 从生产加工过程控制、终产品检测可操作性或进出口口岸检测便利...     

Nitrate and nitrite in vegetables from north China: content and intake

The contents of nitrate and nitrite in potato, cabbage, Chinese cabbage, scallion (shallot), celery, cucumber, tomato, eggplant and wax gourd taken from the north China market from 1998 to 1999 were determined. These vegetables provide the major contribution to the nitrate intake from the diet. The highest content of nitrate was found in celery followed by Chinese cabbage, cabbage, scallion, wax gourd and eggplant. For all the products, a great variation in the content of nitrate was found. Generally, the nitrite content was low. The average intake of nitrate and nitrite from these vegetables was estimated as approximately 422.8 and 0.68 mg day -1 , respectively.     

Nitrate and nitrite in fresh vegetables from queensland

Vegetables were collected near peak harvest from the main production regions in Queensland and were analysed for residues of nitrate and nitrite. A small sample of hydroponic produce was also included in the survey. Nitrite-N from 1 to 4 mg kg^-1 was found only in dwarf beans and in lettuces. Levels of nitrate in potatoes, cabbages and beets were higher than those reported in other surveys and exceeded threshold limits set in one other country. The median nitrate-N concentration measured in hydroponic lettuce (465 mg kg^-1 nitrate-N) was more than twice the median concentration for field-grown lettuce. Poor correlation between total N and nitrate in vegetables raises doubts about the use of total N alone as an indicator of N status.     

Nitrate and nitrite in vegetables on the Danish market: content and intake

The contents of nitrate and nitrite in lettuce, leek, potato, beetroot, Chinese cabbage and white cabbage on the Danish market were determined for 3 years in the period 1993-1997 as part of the Danish food monitoring programme. These vegetables are supposed to provide the major contribution to the intake of nitrate from the diet. Results for nitrate and nitrite in fresh and frozen spinach are also shown. The highest content of nitrate was found in lettuce followed by beetroot, Chinese cabbage, fresh spinach, leek, frozen spinach, white cabbage and potatoes. For all the products a great variation in the content of nitrate was found. For lettuce a characteristic variation throughout the year is clearly seen with the highest content in the winter period the lowest content in the summer period. Generally, the content of nitrite was low but in spinach high contents were found, probably due to improper storage conditions during transportation. The intake of nitrate and nitrite from these vegetables is calculated on the basis of two different consumption surveys. For both surveys the average intake of nitrate from the vegetables included in the monitoring programme is estimated to be approximately 40mg day^-1, whereas for nitrite the average intake is approximately 0.09mg day^-1. The total intake of nitrate and nitrite is estimated to be respectively 61mg day^-1 and 0.5mg day^-1.     

Zn-porphyrin formation in cured meat products: Effect of added salt and nitrite

Zn-porphyrin (Zn-pp) was quantified by fluorescence spectroscopy in the cured and dry cured meat products: Parma ham, Iberian ham, dry-cured ham with added nitrite, cooked ham with added nitrite, raw ham meat, raw bacon and Karree-Speck. The highest amount of Zn-pp was found in dry-cured Parma ham and Iberian ham, while the use of nitrite as curing agent was found to inhibit completely the formation of Zn-pp in meat products. A positive correlation between both Zn content and Fe content and the logarithmic transformed Zn-pp content (measured as fluorescence intensity I_fl) was found for the different cured and dry cured meat products, with correlation coefficients of 0.79 (p < 0.001) and 0.71 (p < 0.01), respectively. Log I_fl correlates best with the Zn content, indicating that the formation of Zn-pp is proportional to the Zn content. A model system with vacuum packed pork in brine with different added levels of sodium chloride with or without nitrite and Zn acetate was investigated in order to further elucidate the mechanism of Zn-pp formation. Zn-pp increased with time (up to 42 days investigated) in non-cured meat and for meat cured solely with NaCl lower than 9%. Addition of nitrite or Zn(II) in the curing brine was found to inhibit formation of Zn-pp confirming the observations from the various cured meat products. It is suggested that a chloride anion assisted dissociation of iron from myoglobin could be rate-determining for Zn-pp formation in meat products.     

Estimated dietary intake of nitrite and nitrate in Swedish children

This study examines the intake of nitrate and nitrite in Swedish children. Daily intake estimates were based on a nationwide food consumption survey (4-day food diary) and nitrite/nitrate content in various foodstuffs. The mean intake of nitrite from cured meat among 2259 children studied was 0.013, 0.010 and 0.007?mg?kg^?1?body?weight?day^?1 in age groups 4, 8–9 and 11–12 years, respectively. Among these age groups, three individuals (0.1% of the studied children) exceeded the acceptable daily intake (ADI) of 0.07?mg?nitrite?kg^?1 body weight?day^?1. The mean intake of nitrate from vegetables, fruit, cured meat and water was 0.84, 0.68 and 0.45?mg?kg^?1 body weight?day^?1 for children aged 4, 8–9 and 11–12 years, respectively. No individual exceeded the ADI of 3.7?mg?nitrate?kg^?1 body weight?day^?1. However, when the total nitrite intake was estimated, including an estimated 5% endogenous conversion of nitrate to nitrite, approximately 12% of the 4-year-old children exceeded the nitrite ADI. Thus, the intake of nitrite in Swedish children may be a concern for young age groups when endogenous nitrite conversion is included in the intake estimates.     

Nitrite and nitrate content in meat products and estimated intake in Denmark from 1998 to 2006

The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg^?1 for most products up to 150 mg kg^?1 for special products) have not been exceeded, except for a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000–02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole period with levels varying between 6 and 20 mg sodium nitrite kg^?1 with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day^?1, which is very low compared with the total intake of 61 mg day^?1. The mean intake of sodium nitrite was 0.017 and 0.014, 0.009 and 0.008, and 0.007 and 0.003 mg kg^?1 body weight day^?1 for men and women in the age groups 4–5, 6–14 and 15–75 years, respectively, which was much lower than the acceptable daily intake (ADI) of 0.09 mg kg^?1 body weight day^?1. The 99th percentile for the group of 4-year-olds was 0.107 and 0.123 mg kg^?1 body weight day^?1 for boys and girls, respectively, and the 95th percentile was 0.057 and 0.073 mg kg^?1 body weight day^?1 for boys and girls, respectively, highest for the girls. With fewer than 100 boys and girls in the 4–5-year age group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite.     

Exposure estimates of nitrite and nitrate from consumption of cured meat products by the U.S. population

The dietary exposures of nitrite and nitrate from consumption of cured meat products were estimated for the U.S. population aged 2 years and older, and children aged 2 to 5 years, using both 2-day food consumption data from the publicly available combined 2009–2012 National Health and Nutrition Examination Survey (NHANES) and 10–14-day food consumption data from the 2009 and 2012 NPD Group, Inc. National Eating Trends-Nutrient Intake database (NPD NET-NID), and residual nitrite and nitrate levels in cured meat products available from the recent American Meat Institute Foundation/National Pork Board (AMIF/NPB) national market survey of the nitrite and nitrate levels in cured meat products in the U.S.A. The dietary exposure for consumers of cured meat products (eaters-only) was estimated at the mean and 90th percentile for three exposure scenarios: low exposure, average exposure, and high exposure, to account for the range in the amount of nitrite and nitrate in a given cured meat product category. In addition, a cumulative exposure that takes into account all cured meat product categories containing nitrite and nitrate was determined, and the relative percent contribution of each cured meat product category to the cumulative exposure was estimated. Cured, cooked sausages and whole-muscle brine-cured products were the two major contributing categories to dietary exposure of nitrite and nitrate for both U.S. population aged 2 years and older and children aged 2–5 years.     

Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products.     

Incidence of aflatoxin B1 in the Egyptain cured meat basterma and control by γ‐irradiation

In the present studies trials have been carried out to investigate the occurrence of aflatoxin B₁ in the Egyptian cured meat basterma and to control such contamination by γ‐rays. Basterma was prepared from fresh salted meat coated with spice paste and stored at room temperature. The total mould counts of basterma samples varied from 10³ to 10⁶ cfu/g in summer months and from 10² to 10⁵ cfu/g in winter months. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium and Cladosporium were the most common fungal genera isolated from basterma samples and its components. Basterma samples contained total aflatoxins at levels from 2.8 to 47 μg·kg^–1. Aflatoxins were determined in the spice paste at levels from 9.6 to 120 μg·kg^–1 and in pepper (285.6 μg·kg^–1), garlic (224.4 μg·kg^–1), fenugreek (194.2 μg·kg^–1), coriander (166.4 μg·kg^–1) and capsicum (42.4 μg·kg^–1). At an irradiation dose level of 3 kGy, only one sample each of pepper, fenugreek, and spice paste were contaminated with aflatoxins and all basterma samples and its components were free from aflatoxins at an irradiation dose level of 5 kGy.     

北京市海淀区市售肉制品和腌制蔬菜中亚硝酸盐含量及居民知信行调查

目的了解北京市海淀区市售肉制品和腌制蔬菜中亚硝酸盐含量,并调查该地区居民对亚硝酸盐的知识、态度以及对含有亚硝酸盐食物的摄入情况。方法采集市售肉制品和腌制蔬菜样品34份,经过预处理后采用分光光度法检测样品中亚硝酸盐含量。采用自拟调查表和偶遇抽样面访采集数据,使用Epidata 3.1对问卷进行平行双录入,使用SPSS 20.0进行统计分析。结果样品中亚硝酸盐含量均在食品安全国家标准允许范围内,平均亚硝酸盐含量从高到低依次为香肠、酱卤肉、腌腊肉、腌制蔬菜,差异具有统计学意义(P0.05)。受访者对亚硝酸盐的危害及亚硝酸盐含量高的食物认识不足,仅有54.5%的人表示会有意减少食用亚硝酸盐含量高的食物;受访者在上个月内食用肉制品及腌制蔬菜的量和频率不高。结论北京市海淀区居民通过肉制品及腌制蔬菜摄入过量亚硝酸盐的风险很低,可以安全食用。     

河南省居民肉及肉制品中铜摄入水平及其风险评估

目的以河南省肉及肉制品中铜为例,演示采用简单分布评估方法,评价河南省居民肉及肉制品饮食中铜摄入情况及其潜在的健康风险。方法 2014—2015年在河南省16个省辖市随机采集肉及肉制品309份,按照食品中铜测定的原子吸收光谱法标准操作程序进行检测,结合河南省2010—2012年开展的居民营养与健康状况监测中肉及肉制品的消费量数据,采用简单分布模型(确定性评估)方法,借鉴文献发表的肉及肉制品对膳食中铜的贡献率,计算河南省不同年龄组人群全膳食中铜摄入水平及其潜在的健康风险。结果肉及肉制品中铜的平均含量为0.556 mg/100 g,中位数为0.060 mg/100 g,不同肉及肉制品中铜平均含量最高为内脏(1.561 mg/100 g),铜平均含量最低的为猪肉(0.068 mg/100 g)。河南省居民每天通过进食肉及肉制品的铜平均摄入量为0.046 mg/d,高端(P95)摄入量为0.144 mg/d。利用文献报道的肉及肉制品贡献率外推全膳食中铜摄入量后发现,河南省居民全膳食中铜的平均和P95摄入量分别为0.638和1.977 mg/d。个体评估结果显示,全人群铜摄入量处于推荐摄入量(RNI)与可耐受最高摄入量(UL)之间的个体比例为21.12%(801/3 792),处于EAR和RNI之间的个体比例为8.10%(307/3 792),而低于平均需要量(EAR)、大于UL的人群比例分别为69.75%(2 645/3 792)和1.03%(39/3 792)。结论河南省全人群膳食中铜摄入量缺乏的风险较高,铜过量的风险较低。     

茶多酚和维生素C对腌制猪肉亚硝酸盐残留量和脂肪氧化的影响

以腌制猪肉模型为材料,研究不同含量的茶多酚和维生素C对色泽、残留亚硝酸盐含量以及脂肪氧化TBARS值的影响。结果表明,茶多酚和维生素C都在一定程度上降低了腌制模型中亚硝酸钠的残留量,维生素C的作用效果要显著强于茶多酚(p<0.05)。腌制过程中TBARS值呈逐渐增加的趋势,茶多酚和维生素C有降低TBARS值的作用,茶多酚的作用效果要强于维生素C。在腌制过程中,维生素C组的色泽显著高于茶多酚组(p<0.05),而蒸煮后各组之间色泽差异不显著(p>0.05)。      

不同溶解性膳食纤维的功能特性差异浅析 及其在肉制品中应用

膳食纤维是一种植物成分,在消化过程中胃中的酶不能将其分解,是人类所需的第七大营养素。膳食纤维按其溶解性可分为可溶性和不溶性膳食纤维两大类,而且不同溶解性膳食纤维功能特性方面有很大差异,一般可溶性膳食纤维形成溶胶或凝胶,有很强的吸附性和清除能力,一般研究水溶性膳食纤维的对胆酸、胆固醇及有害物质的吸附性能,以及清除自由基的能力。不溶性膳食纤维主要研究粒径、温度等因素,对膳食纤维的膨胀力、持水力、吸油力和结合水力的影响。可溶性与不溶性膳食纤维的制备工艺方法存在差异,得率因品种不同有较大差异,持水力、溶胀率等理化特性也差异很大。本文还介绍了国内外将多种不同类型和来源的膳食纤维添加在肉制品(香肠、火腿、重组肉制品、凝胶肉制品、汉堡等)中的应用研究进展。目前对于不同溶解性膳食纤维的性质还没有确切科学的结论。如果能将不同膳食纤维本身的性质研究透彻,确定什么理化特性或结构特征赋予了膳食纤维在不同功能食品中的各种功能特性,将使商业与研究如何选择和制备合适品种的膳食纤维提供科学依据。     

Polycyclic aromatic hydrocarbons (PAHs) in meat products and estimated PAH intake by children and the general population in Estonia

The concentrations of benzo[a]pyrene and 11 other polycyclic aromatic hydrocarbons (PAHs) were analysed from 322 commercial, cured meat products and 14 home-grilled meat samples as part of the Estonian food safety monitoring programme during 2001-2005. The maximum acceptable concentration of 5 µg kg^-1 for benzo[a]pyrene was exceeded in 3.4% of samples. The highest PAH concentrations were detected in home-grilled pork samples. Using of disposable grilling unit resulted in 1.6 times higher PAH concentrations compared to the traditional wood-burning grill. The average intake of benzo[a]pyrene and sum of 12 PAHs from meat products was estimated for children (age 1-16 years) on the basis of an individual food consumption questionnaire and, for the general population, based on national food consumption data. The highest total PAH concentrations detected were 16 µg kg^-1 in smoked meat and ham, 19 µg kg^-1 in smoked sausage and 6.5 µg kg^-1 in smoked chicken samples. Since smoking and grilling are prevalent meat-cooking methods in Estonia, the impact of meat products is assessed to be significant in overall PAH intake.     

Recent advances in heterocyclic aromatic amines: An update on food safety and hazardous control from food processing to dietary intake

Heterocyclic aromatic amines (HAAs) as probable carcinogenic substances are mainly generated in meat products during thermal processing. Numerous studies have contributed to the analysis, formation, and mitigation of HAAs during food processing. However, few articles have comprehensively reviewed food safety aspects from both food processing and dietary intake regarding the formation, mitigation, metabolism, biomarkers for exposure, hazard control, and risk assessment of HAAs, and related food safety researches. Several factors may influence the generation of HAAs, including processing temperature, processing time, and chemical composition of the meat. Nonetheless, these mutagenic compounds are attenuated to different levels by the addition of natural or synthetic flavorings and antioxidant‐rich marinades, as well as pretreatments using technique such as microwave heating. After dietary intake, different types of HAAs are metabolized in humans by several enzymes, including cytochrome P450s, peroxidases, N‐acetyltransferases, sulfotransferases, uridine diphosphate‐glucuronosyltransferases, and glutathione S‐transferases. Their primary metabolites are further conjugated with DNA or ultimately excreted in urine and feces. The 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine in hair as well as DNA, hemoglobin, and serum albumin adducts has been considered as biomarkers for exposure assessment. Dietary intake information obtained from questionnaires and the results of epidemiological investigations have shown a positive relationship between the intakes of red meat and processed meat and high risk of cancer incidence. As several cancers have been reported to be associated with HAAs, HAAs should be both effectively reduced during food processing and controlled from dietary intake to facilitate human health.     

Determination of selenium in selected food samples from Argentina and estimation of their contribution to the Se dietary intake

An optimised FI-HGAAS method was applied to determine the total selenium concentrations in selected high consumption food (fish, beef, chicken, milk, rice, wheat flour, egg) and to estimate their contribution to the Argentinean dietary intake, whose information is scarce nowadays. Through several optimisation steps a suitable method was achieved showing satisfactory figures of merit for all matrices. Average recovery was 96%, RSD < 5%, LODs ranged 2.0–7.0 μg kg⁻¹ and the accuracy was assessed using DOLT-3 NRC certified reference material. Meat and eggs showed the highest values (in μg kg⁻¹, beef: 42–153; chicken: 62–205; fish: 94–314; canned tuna: 272–282; eggs: 134–217), minor values were found for wheat flour (22–42), rice: (<22), pasta (47–64) and milk (<7–9). An estimated intake of 32 and 24 μg day⁻¹ for adult men and women, respectively, suggested a deficient Se intake, leading to further comprehensive surveys of Se occurrence in Argentina.