Gluten contamination of cereal foods in Canada

Persons suffering from celiac disease (CD) must avoid foods containing gluten or those contaminated with wheat, barley, or rye. This study was designed to estimate gluten contamination of cereal-based foods available in Canada, whether labelled gluten-free or not. About half of the 148 foods sampled were labelled as gluten-free. According to R5-enzyme-linked immunosorbent assay (ELISA), twenty-three cereal-based foods (or 15%) contained more than 20 mg of gluten per kg, including sixteen regular and seven gluten-free foods, the latter being the least contaminated. When used in combination with R5-ELISA, AOAC-ELISA (not detecting barley) was a simple and efficient tool to roughly estimate the nature of the gluten contamination, which was later confirmed by real-time polymerase chain reaction for barley, and wheat/barley/rice. Rice-, corn- or quinoa-based foods were the safest for celiac patients. In addition to misleading food labelling for both gluten-rich and gluten-free foods, critical issues for persons with CD included foods made with oats or buckwheat (contaminated with wheat and barley gluten) in addition to those, such as breakfast cereals, specifically enriched with barley malt ingredients.     

常见6种杂粮与2种主粮的抗氧化活性比较研究

目的：比较常见6种杂粮：荞麦(甜荞、苦荞)、小米、糜米(粳性、糯性)、玉米、薏米、燕麦与2种主粮：大米、小麦食用部分的总酚、黄酮含量及其存在形式和抗氧化活性差异,并分析总酚、黄酮含量与抗氧化活性之间的相关性。方法：采用Folin-Ciocalteu法测定总酚含量,NaNO2-Al(NO)3测定黄酮含量;DPPH自由基法、ABTS+ ·法、β-胡萝卜素-亚油酸乳化液法和还原力法评价样品的抗氧化能力。结果：总酚含量由高至低为：苦荞、甜荞、燕麦、薏米、玉米、小米、粳性糜米、小麦、糯性糜米、大米,并且除小米、糯性糜米外其他样品提取物的多酚主要以自由态存在,占总酚的64.18%～98.70%;黄酮含量最高的为薏米、燕麦次之,且均多以自由态存在;杂粮的抗氧化活性高于主粮,其中苦荞清除DPPH自由基能力、ABTS+ ·能力和总还原力最强,甜荞次之,而小米抑制β-胡萝卜素褪色能力最强;同时,抗氧化活性与总酚含量之间具有良好的线性关系,与黄酮含量的相关性不明显。结论：杂粮的总酚含量及总抗氧化活性高于主粮,其中苦荞最为突出,因此,推荐增加日常杂粮食用量以弥补主粮膳食中多酚物质含量过低的不足。     

Gluten contamination in manufactured gluten-free foods in Turkey

ABSTRACT

Gluten contamination in manufactured gluten-free foods (mGFFs) is a major health, well-being and economic issue worldwide for both mandatory and voluntary GFF-consumers. Although scarce, a number of surveys have shown that up to 21.5 % of mGFFs in circulation in the market are contaminated with gluten. However, at the present time there is no published work reporting gluten contamination in mGFFs produced in Turkey. In this paper miscellaneous mGFFs produced in Turkey were analysed for gluten concentration (G) to fill this knowledge gap, and to compare the situation in Turkey with worldwide efforts on this issue. A total of 200 mGFFs from 8 product categories (snack, pasta, bread, cookie, cracker, farina, traditional and others), and manufactured using 7 main ingredients (cereal mixture, buckwheat, corn, rice, locust bean, potato, and others) were analysed. A significant portion of mGFFs (17.5 %) were contaminated with gluten and therefore unacceptable as being GFF. The results point to buckwheat as the main cause of this contamination. If buckwheat is excluded, the ratio of unacceptable mGFFs dramatically decreases to 6.3 % and probably to 1.8 %, which are comparable figures to those reported for other countries. Almost all countries are subjected to the same regulations on GFFs, and the problem of gluten contamination could readily be solved to a great extent if pre-market measures are mandated. Enforcing mGFF-producers to screen their raw materials and final products to detect the presence of gluten, and preventing the release of contaminated mGFFs into the market would be a practical measure in favour of all stakeholders involved in GFF-consumption.     

Gluten contamination in the Canadian commercial oat supply

A growing body of evidence suggests that a majority of people with celiac disease and on a gluten-free diet can safely consume pure oats in moderate amounts; however, previous studies have indicated that the commercial oat supply in other countries, and in Canada to some extent, is contaminated with other grains. This study has confirmed that the commercial oat supply in Canada is heavily contaminated with gluten from other grains. Approximately 88% of the oat samples (n = 133) were contaminated above 20 mg kg(-1) and there were no differences between the oat types tested. Only one gluten-free variety of oats was analysed and it consistently provided negative results in all analyses. It is difficult to determine where the contamination originates, but there are possibilities for cross-contamination in the field, in the transport of the grain, in the storage of the grain, and in the milling and packaging facilities. It is clear from this study that only those products that have been certified 'pure' oats would be appropriate for a gluten-free diet.     

Low folate content in gluten-free cereal products and their main ingredients

Folate content in some gluten-free cereal products and their main ingredients was determined using a validated method based on reversed-phase high performance liquid chromatography (HPLC) with fluorescence and diode array detection. The main folate forms found in gluten-free products were 5-methyl-tetrahydrofolate and tetrahydrofolate. Starches and low protein flours commonly used as main components in gluten-free products appeared to be poor folate sources with folate content ?6 μg/100 g fresh weight. Folate content in gluten-free breads was higher (15.1–35.9 μg folate/100 g fresh weight) due to use of bakery yeast which is a rich folate source. Overall, folate content in gluten-free products was lower than in their gluten-containing counterparts. Therefore, fortification of gluten-free products with folic acid or enrichment of these products with nutrient-dense fractions of cereals naturally free from gluten (such as buckwheat, quinoa, amaranth or millet) can be of interest.     

Gluten contamination of naturally gluten-free flours and starches used by Canadians with celiac disease

A large national investigation into the extent of gluten cross-contamination of naturally gluten-free ingredients (flours and starches) sold in Canada was performed. Samples (n = 640) were purchased from eight Canadian cities and via the internet during the period 2010–2012 and analysed for gluten contamination. The results showed that 61 of the 640 (9.5%) samples were contaminated above the Codex-recommended maximum level for gluten-free products (20 mg kg^–1) with a range of 5–7995 mg kg^–1. For the ingredients that were labelled gluten-free the contamination range (5–141 mg kg^–1) and number of samples were lower (3 of 268). This picture was consistent over time, with approximately the same percentage of samples above 20 mg kg^–1 in both the initial set and the subsequent lot. Looking at the total mean (composite) contamination for specific ingredients the largest and most consistent contaminations come from higher fibre ingredients such as soy (902 mg kg^–1), millet (272 mg kg^–1) and buckwheat (153 mg kg^–1). Of the naturally gluten-free flours and starches tested that do not contain a gluten-free label, the higher fibre ingredients would constitute the greatest probability of being contaminated with gluten above 20 mg kg^–1.     

A survey of the occurrence of the mycotoxin moniliformin in cereal samples from sources worldwide.

A method is reported for the determination of the Fusarium mycotoxin moniliformin in cereals. The samples after extraction with acetonitrile/water are cleaned-up on a combination of reverse-phase and strong-anion exchange disposable cartridge columns. The extract is then analysed by ion-pair HPLC with UV detection. The method gave recoveries from 81 to 96% and a limit of detection of 0.05 mg/kg. A UK survey of 36 samples of maize products (principally meal and flour) generally showed detectable but low levels of contamination ranging from 0.05 to 0.25 mg/kg (with the exception of three samples where moniliformin levels were less than 0.05 mg/kg). Sixty-four samples of maize from ten different countries showed generally higher levels of moniliformin contamination, with samples from Gambia and South Africa containing 3.16 and 2.73 mg/kg respectively. Field samples of maize, oats, wheat, rye and tricticale that were hand-selected as showing signs of visible fungal damage were obtained from Poland. Moniliformin was consistently present at high levels with amounts ranging from 0.5 to 38.3 mg/kg being associated with F. avenaceum contamination and amounts ranging from 4.2 to 399.3 mg/kg being associated with the presence of F. subglutinans.     

Coeliacs cannot live by gluten‐free bread alone – every once in awhile they need antioxidants

This comprehensive review, covering scientific papers published from 2013 until now, deals with the bioactivity of available gluten‐free matrices. For this purpose, cereals (rice, maize, sorghum, teff and millets), pseudocereals (buckwheat, quinoa and amaranth) and noncereals (pulses as lentils, fruits as bananas, vegetables as potatoes and nuts as chestnuts, among others) sources are studied. The current trends in enhancing the antioxidant activity of gluten‐free baked products by incorporating natural bioactive compounds are presented. This review covers a wide range of natural bioactive sources such as starchy materials or its by‐products; spices, herbs or green plant materials and vegetable and seeds or fruits. Special emphasis was put on describing the changes in antioxidant activity that can occur, between raw matrices and enriched final products, during baking process. Possible future trends in the improvement of antioxidant properties of gluten‐free baked products, based on bioactive sources which have already been applied in the gluten bread industry, were also discussed.     

三种杂粮及其复合低温火腿肠营养成分分析及评价

分别检测了燕麦、苦荞麦、小米3种杂粮原料,以及所对应的杂粮复合低温火腿肠的营养成分,并对其进行了营养价值评价。结果表明:燕麦片、苦荞麦粉、小米3种杂粮原料的脂肪含量都较低,均在10%以下。燕麦片的蛋白质含量最高,达到13.4%,且所含钙、铁、锌均较高,分别为683、48.1、25.3mg/kg。苦荞麦粉硒元素的含量最高,达到0.12mg/kg。对杂粮原料进行了氨基酸营养评价,小米的E/N值为55.03%,最接近FAO/WHO标准模式。杂粮复合低温火腿肠中,蛋白质含量均高于GB/T 20712—2006《火腿肠》国家标准指标,淀粉含量均在10%以下。小米复合低温火腿肠中VB1、VB2含量相对较高,分别达到156.6μg/100g和12.8μg/100g。其他的功能性营养成分检测结果表明:苦荞麦复合低温火腿肠中特有的生物活性物质黄酮含量达到了2mg/kg,膳食纤维含量最高,达到了3.4%。对杂粮低温复合火腿肠进行了INQ值评价,3种复合低温火腿肠的钙、铁、锌、VB1的INQ值均高于1,其中小米复合低温火腿肠的INQ值总体最高。杂粮复合低温火腿肠理化及卫生指标结果表明,3种低温火腿肠的理化及卫生指标均符合GB/T 20712—2006《火腿肠》的相关规定,表明产品卫生安全指标合格。     

应用Illumina NovaSeq测序技术比较3 种杂粮对大鼠肠道菌群的影响

为探究燕麦、荞麦和小米对健康大鼠肠道结构、肠道菌群及肠道中短链脂肪酸（short-chain fatty acids,SCFAs）含量的影响,本实验将48 只SPF级雄性SD大鼠随机分为4 组（空白对照组（饲喂标准维持饲料）、燕麦组（饲喂含22%（质量分数,下同）燕麦的饲料）、荞麦组（饲喂含22%荞麦的饲料）和小米组（饲喂含22%小米的饲料））,每周测定大鼠体质量,12 周后处死大鼠,取肝脏、结肠组织及结肠内容物,对大鼠肝脏和结肠组织进行病理学检测;应用Illumina NovaSeq高通量测序技术检测大鼠肠道菌群变化;利用液相色谱-质谱联用仪检测大鼠结肠内容物SCFAs含量。结果表明,燕麦可增加大鼠肠道菌群多样性,提高大鼠结肠乳杆菌属（Lactobacillus）和阿克曼氏菌属（Akkermansia）丰度;荞麦和小米可增加厚壁菌门（Firmicutes）相对丰度,降低疣微菌门（Verrucomicrobia）和拟杆菌门（Bacteroidetes）相对丰度;燕麦、荞麦和小米均可降低拟杆菌属（Bacteroides）丰度;燕麦和小米可显著提高大鼠结肠内乙酸和总SCFAs含量（P＜0.05）,小米可显著提高丙酸和异丁酸含量（P＜0.05）。综上,燕麦对大鼠肠道菌群具有一定的改善作用,荞麦和小米对肠道菌群的影响相似度较高,相关研究结果可为谷物功能食品的开发提供科学依据。     

Occurrence of type A trichothecenes in conventionally and organically produced oats and oat products

Among cereals, oats are known to be very frequently contaminated with type A trichothecenes and so they can play a major role in the exposition of the consumer to these mycotoxins. Seventy representative oat samples of both conventional and organic production were drawn at mills and at wholesale stage according to Commissions Regulation (EC) No 401/2006 and analyzed for nine type A trichothecenes by LC-MS/MS. High contamination rates were found for most of the toxins in conventional as well as in organic products (e. g. 100% for T-2 toxin or 99% for HT-2 toxin). The mean concentration of T-2/HT-2 (sum of the toxins) was 17 +/- 18 microg/kg (mean +/- SD) in all samples, 27 +/- 21 microg/kg in conventional, and 7.6 +/- 4.6 microg/kg in organic products, respectively. The highest T-2/HT-2 level has been determined in conventionally produced oat flakes (85 microg/kg). The mean level of T-2 tetraol (9.5 +/- 7.7 microg/kg) in all samples was found to be even higher than that of T-2 (5.1 +/- 6.0 microg/kg), whereas levels of T-2 triol, 4,15-diacetoxyscirpenol, 15-monoacetoxyscirpenol, and neosolaniol were considerably lower. For oats and oat products from organic farming contamination levels of T-2, HT-2, T-2 triol, T-2 tetraol, and neosolaniol were significantly lower. The results are discussed with respect to possible health risks for the consumer.     

Occurrence and fate of Fusarium mycotoxins during commercial processing of oats in the UK

The commercial processing of oats is different from that of other cereals, such as wheat and maize. In northwest Europe, oats also appear to be more susceptible to contamination with HT-2 and T-2 toxins than other cereals. Mycotoxins, such as deoxynivanol and zearalenone, in cereals are already controlled by EU legislation. With regard to additional, impending legislation, this study examined HT-2 and T-2 toxins together with zearalenone, deoxynivalenol and other related toxins in a commercial oat mill and how the concentrations varied from raw oats to the final prepared oat flakes. Concentrations of each Fusarium mycotoxin fell by 90-95% during the process, with the major loss being a physical distribution occurring at the de-hulling stage. Initial studies of losses occurring at other stages, such as kilning or de-branning of prepared oat groats, suggest these to be small. The use of colour sorting after kilning showed higher concentrations of each mycotoxin in the discoloured groats. The feasibility of developing a predictive tool for the oat industry is examined.     

The content of proteic and nonproteic (free and protein-bound) tryptophan in quinoa and cereal flours

The content of proteic and nonproteic (free and protein-bound) tryptophan and of proteins in quinoa, wheat, rice, maize, barley, oat, rye, spelt, sorghum and millet flours was determined. Protein content and proteic tryptophan of quinoa were similar to that of wheat and spelt, but higher than in other cereals. Free tryptophan in quinoa flour showed values similar to those of wheat, oat and sorghum Kalblank, lower than those of barley, spelt and pearl millet, but higher than in rice, maize, rye, sorghum DK 34 – Alabama hybrid. In addition, nonproteic tryptophan appears bound both to water soluble proteins and to proteins soluble at pH 8.9. The results are discussed regarding the importance of the nonprotein tryptophan fraction, the only one able to enter the brain, that is more easily absorbed, so guarantees a greater amount available for uptake by the central nervous system.     

Optimization and Validation of a Fluorescence Polarization Immunoassay for Rapid Detection of T-2 and HT-2 Toxins in Cereals and Cereal-Based Products

A fluorescence polarization (FP) immunoassay has been optimized and validated for rapid quantification of T-2 and HT-2 toxins in both unprocessed cereals, including oats, barley and rye, and cereal-based products for direct human consumption, such as oat flakes, oats crispbread and pasta. Samples were extracted with 90 % methanol, and the extract was filtered and diluted with water or sodium chloride solution prior to the FP immunoassay. Overall mean recoveries from spiked oats, rye, barley, oat flakes, oats crispbread and pasta ranged from 101 to 107 %, with relative standard deviations lower than 7 %. Limits of detection (LODs) of the FP immunoassay were 70 μg/kg for oats, 40 μg/kg for oat flakes and barley, 25 μg/kg for pasta and 20 μg/kg for rye and oats crispbread. The trueness of the immunoassay was assessed by using two oat and oat flake reference materials for T-2 and HT-2 toxins, showing good accuracy and precision. Good correlations (r?>?0.953) were observed between T-2 and HT-2 toxin contents in naturally and artificially contaminated samples determined by both FP immunoassay and ultra-high-performance liquid chromatography (UHPLC) with immunoaffinity column cleanup used as reference method. These results, combined with rapidity and simplicity of the assay, show that the optimized assay is suitable for high-throughput screening, as well as for reliable quantitative determination of T-2 and HT-2 toxins in cereals and cereal-based products.     

Investigation of product quality, sensory profile and ultrastructure of breads made from a range of commercial gluten-free flours compared to their wheat counterparts

Bread is a major staple food consumed daily in all parts of the world. A significant part of the human population cannot tolerate gluten, a storage protein found in wheat, rye and barley, and therefore, products made from alternative cereals are required. During this study, the bread-making potential of seven gluten-free flours, wheat and wholemeal wheat flour was compared. Fermentation potential of the different flours was determined, showing that dough development height of gluten-free and wholemeal wheat samples was lower than for wheat and oat flour. Apart from standard bread quality parameters such as loaf-specific volume and physical crumb texture, also water activity and shelf life have been determined. The shelf life of gluten-free breads was reduced compared to wheat bread. Aroma profiles were evaluated by a trained panel. Wheat, oat and wholemeal wheat breads were liked moderately, while the remaining samples had lower liking scores. Crumb grain characteristics were investigated using image analysis, and microstructure was observed by scanning electron microscopy. Overall, only breads produced from oat flour were of similar quality to wheat bread, and the utilization of buckwheat, rice, maize, quinoa, sorghum and teff flours resulted in breads of inferior quality.     

Adaptability of lactic acid bacteria and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava and use of competitive strains as starters

The adaptability of lactic acid bacteria (LAB) and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava was investigated using PCR-DGGE and bacteriological culture combined with rRNA gene sequence analysis. Sourdoughs were prepared either from flours of the cereals wheat, rye, oat, barley, rice, maize, and millet, or from the pseudocereals amaranth, quinoa, and buckwheat, or from cassava, using a starter consisting of various species of LAB and yeasts. Doughs were propagated until a stable microbiota was established. The dominant LAB and yeast species were Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus paralimentarius, Lactobacillus plantarum, Lactobacillus pontis, Lactobacillus spicheri, Issatchenkia orientalis and Saccharomyces cerevisiae. The proportion of the species within the microbiota varied. L. paralimentarius dominated in the pseudocereal sourdoughs, L. fermentum, L. plantarum and L. spicheri in the cassava sourdough, and L. fermentum, L. helveticus and L. pontis in the cereal sourdoughs. S. cerevisiae constituted the dominating yeast, except for quinoa sourdough, where I. orientalis also reached similar counts, and buckwheat and oat sourdoughs, where no yeasts could be detected. To assess the usefulness of competitive LAB and yeasts as starters, the fermentations were repeated using flours from rice, maize, millet and the pseudocereals, and by starting the dough fermentation with selected dominant strains. At the end of fermentation, most of starter strains belonged to the dominating microbiota. For the rice, millet and quinoa sourdoughs the species composition was similar to that of the prior fermentation, whereas in the other sourdoughs, the composition differed.     

燕麦、荞麦面条品质提升研究进展

燕麦、荞麦等杂粮营养价值高但缺乏面条制作中需要的面筋蛋白。因此,为兼顾营养与口感的需求,燕麦、荞麦面条制作时通常需要与小麦粉复配,并从原料预处理、加工工艺等方面改良品质。本文从原料预处理（预糊化、灭酶、脱脂、发酵）和加工工艺改进（配方、和面方式、成型方式等）两个方面对燕麦、荞麦面条品质改良的研究现状进行了综述。 在此基础上,深入讨论了当前燕麦、荞麦面条研究中存在的问题,并对其未来的研究前景进行了展望。     

A comparison of contents of group A and B trichothecenes and microbial counts in different cereal species

Concentrations of trichothecenes and the amounts of microbial biomass were compared in grain of bread wheat, durum wheat, triticale, rye, oat and barley. Grain samples came from lines regionalised in Poland grown under identical climatic and agricultural conditions in 2007. Among the six analysed cereals, the highest mean concentration of toxic metabolites of 151.89?µg/kg was found for grain of Triticum durum, whereas the lowest was for barley grain (25.56?µg/kg). The highest contamination with microscopic fungi was recorded in case of barley and rice grain (mean concentrations of ergosterol were 12.53?mg/kg and 11.24?mg/kg, respectively). In case of the analysed cereals, the total microbial biomass expressed in the amount of ATP turned out to be the highest (4.7?×?10⁵ relative light units [RLU]) for rye and oat (3.2?×?10⁵ RLU). The results of the applied classical discrimination analysis indicate a significant diversification of species in terms of all the 11 analysed metabolites.     

无麸质饼干原料及功能性添加成分的研究进展

乳糜泻是患者对面筋不耐受而引起的慢性小肠吸收不良综合征,患者需终身严格遵守无麸质饮食。无麸质食品不含面筋,口感与品质相对较差,研究者通过改进配方、技术等以达到改善的目的。本文介绍了乳糜泻、无麸质饼干的概况及其缺陷,主要对无麸质饼干所用的原料(大米粉、小米粉、藜麦粉、燕麦粉、苋菜粉及其他面粉)、功能性添加成分(亲水胶体、菊粉、酶制剂)进行综述,阐述了国内外关于无麸质饼干的一些研究进展,以期为无麸质饼干的进一步研究与应用提供参考。     

4 种杂粮对大鼠肠道菌群组成及短链脂肪酸的影响

目的：研究我国常见的4 种杂粮（甜荞、燕麦、糜米、谷米）对大鼠肠道菌群组成及短链脂肪酸的影响。方法：将50 只7 周龄SD雄性大鼠（体质量（302.10±9.58）g）随机分为对照组、燕麦组、甜荞组、糜米组和谷米组。对照组饲喂100%的基础日粮,其余各组大鼠分别饲喂50%的基础日粮＋50%实验谷物,连续饲喂6 周。实验期间,每周测定大鼠采食量、体质量。实验期结束,测定大鼠粪便含水率、盲肠和结肠质量、盲肠和结肠内容物pH值及短链脂肪酸含量;此外,测定回肠、盲肠、结肠内容物的菌群组成及分布。结果：饲喂甜荞、燕麦和谷米组大鼠的粪便含水率（分别为25.76%、24.64%和22.45%）显著高于对照组（12.06%）;饲喂谷物杂粮大鼠的盲肠内容物pH值（6.21～6.91）和结肠内容物pH值（6.01～6.15）均显著低于对照组（分别为7.28和6.93）;盲肠内容物短链脂肪酸总量（23.78～37.89 μmol/g）和结肠内容物短链脂肪酸总量（80.82～153.46 μmol/g）均显著高于对照组（分别为14.99 μmol/g和46.15 μmol/g）,且甜荞组最高（分别为37.89 μmol/g和153.46 μmol/g）。大鼠回肠、盲肠和结肠内容物中以厚壁菌门为主;盲肠和结肠内容物厚壁菌门与拟杆菌门的比值低于回肠;盲肠内容物中,4 种杂粮组厚壁菌门和拟杆菌门的比值均低于对照组;甜荞组大鼠回肠、盲肠和结肠内容物厚壁菌门和拟杆菌门的比值分别比对照组低39.2%、38.8%和24.5%。结论：谷物杂粮对大鼠肠道内容物的pH值、短链脂肪酸含量和菌群组成都有重要的调节作用,且甜荞的调节作用尤其显著,在日常膳食中应保证适量杂粮的摄入。