小麦品质简单检测方法研究

介绍了四种简单的小麦品质检测方法，谷蛋白溶涨指数法能反应谷蛋白含量，面粉溶涨体积能反应小麦的淀粉品质，研磨体积法能反应小麦硬度的差异，发芽率法与食品加工特性密切相关。以上四种方法简单易行，投资小，可信度高，与食品加工特性相关性高，可以替代相应的国标方法进行企业产品和原料的质量控制。     

常规PCR法同时检测食品中的小麦、大麦和黑麦致敏原

目的建立一种常规PCR法同时检测食品中的小麦、大麦和黑麦致敏原(WBR155bp)。方法采用ClustalW软件分析小麦ω-醇溶谷蛋白、大麦醇溶谷蛋白和黑麦ω-黑麦碱的核苷酸编码序列的同源性,进而确定同源区域,用Primer Premier5.0基于同源区域设计引物。选取不同种属的植物考查所建立PCR方法的特异性。将小麦粉,大麦粉、黑麦粉与米粉混合制备谷物含量梯度为100%、10%、1.0%、0.1%、0.01%的样品,考查WBR155 bp的检出限。结果扩增产物片段200 bp,可以检测到高度降解的DNA片段。引物WBR155bp对小麦、大麦和黑麦的检出限分别为1.0%, 0.01%和0.1%。结论该方法具有良好特异性,可用于食品中的小麦、大麦和黑麦致敏原的日常检测。     

蛋白质组分分析方法比较研究

采用蛋白质连续累进提取法与组分快速提取法测定了21个小麦面粉样品的蛋白质组分，以比较两种蛋白质组分分析方法的特点。连续累进提取法将小麦蛋白质分离成清蛋白、球蛋白、醇溶蛋白和谷蛋白；快速提取法将小麦蛋白质分离成单体蛋白、可溶性谷蛋白和不溶性谷蛋白。结果表明：单体蛋白与清蛋白、球蛋白、醇溶蛋白含量及清蛋白、球蛋白、谷蛋白之和均无关系；可溶性谷蛋白含量与清蛋白、弱化度呈负相关，与醇溶蛋白、谷蛋白、沉淀值呈极显著或显著正相关；不溶性谷蛋白与醇溶蛋白、谷蛋白、沉淀值、稳定时间、评价值、弱化度呈极显著或显著相关。连续累进提取法适合于小麦品质常规检测，快速提取法适用于小麦早代材料品质检测。两种方法对于预测小麦的加工品质有着相同的重要作用，应根据样品量及检测精度进行选择。     

酶联免疫吸附法(ELISA)检测婴幼儿配方食品中谷蛋白

介绍了利用ELISA法的醇溶谷蛋白试剂盒测定婴幼儿配方食品中的谷蛋白含量。样品经处理后,用提取液提取样品中谷蛋白,提取液经离心,稀释后,用酶联免疫吸附法直接测定。检测的线性范围是5～80μg/kg,相关系数是0.9988,回收率在115.6%～120.6%之间,证明可以用酶联免疫法测定婴幼儿配方食品中的谷蛋白含量。     

实时荧光PCR法测定婴幼儿谷类辅助食品中麸质过敏原成分

目的建立实时荧光PCR法检测婴幼儿谷类辅助食品中麸质过敏原成分的含量。方法样品加入淀粉酶液化后,采用试剂盒方法提取样品DNA,考察大麦Hordein基因、小麦Gliadin基因、黑麦Secl基因和燕麦Avenin基因检测方法的特异性、灵敏度和检出限,幵应用于检测实际样品。结果确定了实时荧光PCR反应体系条件,各个基因的检测方法具有特异性强且灵敏度高,检出限为0.1%。结论该方法操作简便,准确率高,适用于婴幼儿谷类辅助食品中麸质成分的检测。     

谷蛋白大聚体在小麦加工中的作用

谷蛋白大聚体(GMP)是小麦籽粒中最重要的蛋白质聚合体,不溶于1.5%SDS溶液,且分子质量较大,以颗粒形式存在,粒径范围为1~300μm;其含量和分子结构与食品加工品质密切相关,在面制食品加工中的作用远大于可溶性谷蛋白聚合体和单体蛋白。谷蛋白大聚体含量高的小麦品种,其面筋、面团的强度和弹性较大,面包烘烤品质较好,面条拉伸特性较好。谷蛋白大聚体在面团和面过程中会发生解聚,其含量、粒径和分子质量均降低;而在面团醒发过程中又会发生重聚。面条面坯形成过程中,谷蛋白大聚体含量的降低程度远低于传统面团,而凝胶强度的变化趋势则与传统面团相反。     

一种适用于大规模转基因作物PCR检测的简易DNA提取方法

近年来,转基因农作物的数量和种类大幅度增加,其安全性一直受到各国政府的重视和关注,转基因食品的检测也是各国贸易壁垒的一个重要方面.PCR技术作为—种快速、准确的核酸检验方法,广泛地应用于转基因农作物和食品的检测中.DNA样品的制备谜度和质量是PCR检测方法的限速步骤之一,本文改进了碱裂法提取植物DNA,并与SDS快速提取法及CTAB法作比较,用于不同长度片段的PCR扩增.结果显示:利用改进后的碱裂解法提取的DNA为模板可以稳定扩增出1000bp以内的片段,这是一种简易的适合于大规模转基因作物和食品PCR检测的DNA提取方法.     

转基因食品检测方法的现况与进展

为给转基因食品检测提供参考 ,介绍包括除草剂生物分析法 (herbicidebioassays)、western印迹法 (Westernblot)、酶联免疫吸附试验法 (enzyme linkedimmunosorbentassay ,ELISA)、southern印迹法(Southernblot)、聚合酶链反应法 (PolymeraseChainReaction ,PCR)在内的蛋白质检测和DNA检测方法。一些新的方法如近红外光谱法 (near infraredspectroscopy)、DNA微阵列技术法 (Microarray)等略做介绍。对这些方法的基本原理、优缺点和应用范围以及存在的问题进行了分析 ,可供转基因食品检测研究选择分析方法时借鉴。     

植物源性食品DNA提取方法的建立及几种方法比较

以大豆和马铃薯植物源性食品为研究对象,比较了研究所建立的基于磁珠的DNA提取方法、3种商品试剂盒法和传统CTAB法共5种方法提取各种食品基因组DNA的效果;通过琼脂糖凝胶电泳、紫外分析法、定性PCR和实时荧光定量PCR法对所提取的DNA进行检测,比较所得DNA的浓度和纯度,以及对下游检测的适用性。结果表明,与其他几种提取方法相比,研究所建立的方法提取到的DNA浓度稍低,但纯度较高,而且对于豆油和淀粉样品,可很好地提取到基因组片段,满足后续PCR检测要求。     

小麦致敏蛋白的研究进展

小麦是世界最主要的粮食作物之一,但也是8种主要的致敏食品之一,其所含过敏原可能危及人体健康。文中重点介绍了小麦致敏蛋白即醇溶蛋白、谷蛋白和可溶性蛋白的理化加工特性、结构特点、免疫学特征以及小麦脱敏等方面的研究情况。     

Impact of irradiation and thermal processing on the immunochemical detection of milk and egg allergens in foods

There is little information available on the antigenicity of allergens in foods subjected to gamma irradiation and thermal processes. The objective of the study was to evaluate the effects of gamma irradiation and thermal processing on the recovery of milk and egg allergens in foods prepared using irradiated wheat flour incurred with these allergens. Bread, boiled pasta and extruded cereal were selected as food matrices for the study.Allergen detection was performed using Surface Plasmon Resonance (SPR) and commercially available enzyme linked immunosorbent assay (ELISA) kits. Protein structure was characterized using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and circular dichroism (CD) spectroscopy. The ELISA kits performed well in detecting allergens in the unprocessed flours with recoveries ranging from 63–120%. The results for dough and uncooked pasta were similar to those of unprocessed flours. Recoveries for boiled pasta were significantly (p ≤ 0.05) reduced. The lowest allergen recoveries were obtained in bread samples. Allergen recoveries in gamma irradiated samples depended on the irradiation dose, the type of ELISA kit used, the tested matrix, and the processing method. FTIR and CD results showed that among the allergens casein was the most thermostable followed by ovomucoid. β-Lg and ovalbumin showed thermal sensitivity. In conclusion, gamma irradiation may affect the antigenicity of allergenic food residues at low levels depending on the food matrices and the processing methods.     

Structural, biological, and evolutionary relationships of plant food allergens sensitizing via the gastrointestinal tract

The recently completed genome sequence of the model plant species Arabidopsis has been estimated to encode over 25,000 proteins, which, on the basis of their function, can be classified into structural and metabolic (the vast majority of plant proteins), protective proteins, which defend a plant against invasion by pathogens or feeding by pests, and storage proteins, which proved a nutrient store to support germination in seeds. It is now clear that almost all plant food allergens are either protective or storage proteins. It is also becoming evident that those proteins that trigger the development of an allergic response through the gastrointestinal tract belong primarily to two large protein superfamilies: (1) The cereal prolamin superfamily, comprising three major groups of plant food allergens, the 2S albumins, lipid transfer proteins, and cereal alpha-amylase/trypsin inhibitors, which have related structures, and are stable to thermal processing and proteolysis. They include major allergens from Brazil nut, peanuts, fruits, such as peaches, and cereals, such as rice and wheat; (2) The cupin superfamily, comprising the major globulin storage proteins from a number of plant species. The globulins have been found to be allergens in plant foods, such as peanuts, soya bean, and walnut; (3) The cyteine protease C1 family, comprising the papain-like proteases from microbes, plants, and animals. This family contains two notable allergens that sensitize via the GI tract, namely actinidin from kiwi fruit and the soybean allergen, Gly m Bd 30k/P34. This study describes the properties, structures, and evolutionary relationships of these protein families, the allergens that belong to them, and discusses them in relation to the role protein structure may play in determining protein allergenicity.     

饼干模型对小麦及花生过敏原消化稳定性和免疫活性的影响

食品加工或食物基质可以不同程度地影响过敏原消化稳定性和免疫原性。然而,对食品加工和食物基质对 食物模型中过敏原的影响却知之甚少。本实验通过体外模拟胃肠消化的方式,包括模拟口腔咀嚼、胃部消化和十二 指肠消化,采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和免疫印迹的方法,分析焙烤模型饼干中小麦过敏原和花生 过敏原的消化特性和免疫原性。结果显示：小麦和花生蛋白均可被胃蛋白酶迅速水解,醇溶蛋白、谷蛋白等致敏原 被降解成低分子质量多肽;可溶性蛋白中花生过敏原Ara h 1和Ara h 3基本消失,Ara h 2/6耐受胃肠消化;酶联免疫 吸附测定结果显示,消化后饼干中过敏原的致敏性降低。综合以上结果表明,饼干模型的消化性质基本不受焙烤加 工和其他基质的影响,免疫原性因致敏原被消化而降低。     

Is the calculation of the gluten content by multiplying the prolamin content by a factor of 2 valid?

Presently, the only essential therapy of celiac disease (CD) is the permanent strict withdrawal of gluten from the diet. With respect to gluten containing foods from wheat, rye, barley, and oats, CD patients have to consume surrogates that must be gluten-free according to the “Codex Alimentarius Standard for Gluten-Free Foods”. The recent “Draft Revised Standard” proposes a gluten threshold of 20 mg per kg gluten-free product. For gluten quantitation, the alcohol-soluble prolamins should be extracted and analyzed by an immunochemical method; the amount of gluten is calculated by multiplying the prolamin content by the factor of 2. To investigate, whether this calculation is valid in any case of contamination of gluten-free products by wheat, rye, barley, and oats, wholemeal or white flours from common wheat, spelt, durum wheat, kamut, emmer, einkorn, rye, barley and oats were analyzed for the ratio of prolamins to glutenins (PROL/GLUT) by a combination of extraction and reversed-phase HPLC procedures. Additionally, different industrial wheat starches were analyzed for their prolamin and total gluten content using different extraction and concentration steps followed by gel permeation HPLC. The results for the cereal flours revealed that the ratio PROL/GLUT was generally higher than 1.0 as proposed by the “Draft Revised Standard” and strongly influenced by cereal species and variety. Common wheat showed the lowest ratio (1.5–3.1), followed by oats and spelt (1.7–3.3), barley (1.4–5.0), durum wheat and kamut (3.1–3.4), emmer (3.5–7.6), rye (6.3–8.2), and einkorn (4.0–13.9). In any case, the gluten content of gluten-free products contaminated with CD activating cereals was generally overestimated, when the prolamin content was multiplied by the factor of 2. In extreme cases, e.g., contamination with rye, the overestimation amounted to 72–79%. Completely different PROL/GLUT ratios were found in ten commercial wheat starches ranging from 0.2 to 4.9. Obviously, the quality of wheat cultivars used for starch production and/or different process parameters, e.g., washing steps, influenced the composition of gluten proteins adherent to starch granules. For wheat starch, the calculation of the gluten content by 2 × PROL may either lead to underestimation (−71% at most) or overestimation (+66% at most). In conclusion, this calculation is invalid; therefore, a future task will be the development of immunoassays with antibodies against all types of storage proteins from wheat, rye, barley, and oats.     

Producer to retailer price transmission in cereal markets of Ethiopia

This paper investigates price transmission between producer and retail prices of teff, wheat, and maize in Amhara and Oromia, the two major cereal markets in Ethiopia. Market and cereal specific asymmetric error correction models were estimated to analyze producer-retail price transmission using monthly data from 2001 to 2011. For seven out of eight crop-market combinations, with the exception of the Amhara wheat market, we found no evidence of asymmetric price transmission from producer to retail prices in the long run. Neither contemporaneous nor long-run price transmission asymmetry was found in either the Amhara or Oromia teff markets. This was also the case for the maize market except that there existed a short-run asymmetric price transmission that disappeared in the long run in Oromia. We therefore conclude that there is no strong empirical evidence to support the purported ‘market power’ or ‘inventory holding’ behaviour in the Ethiopian cereal markets to explain asymmetric vertical price transmission in the long run. The evidence of asymmetric price transmission for the Amhara wheat market, unlike the wheat market in Oromia, may indicate some differential in the quality of infrastructure and the length and complexity of wheat value chains between these two markets. Symmetric price adjustments in these cereal markets suggest that input price changes may have positive long run implications for food security and welfare of the poor in Ethiopia.     

Contents of volume 10

Intolerance reactions to cereal proteins have been frequently reported in patients with allergic and gastrointestinal disease, although not all the reactions may be mediated by an immunological mechanism (e.g. coeliac disease). The isolation and chemical identification of allergens and ‘toxic fractions’ from cereal proteins is reviewed along with the current views on the mechanism of coeliac disease.     

Identification of Bioactive Peptides from Cereal Storage Proteins and Their Potential Role in Prevention of Chronic Diseases

Cereal grains, such as wheat, barley, rice, rye, oat, millet, sorghum, and corn, have been staples in human diets since ancient times. At present, there is a significant body of scientific evidence showing the health benefits of consuming whole grains in chronic disease prevention, particularly in regards to diabetes, cardiovascular disease, and cancer. The objective was to determine bioactive peptides in cereal grains that may prevent cardiovascular disease, cancer, inflammation, and diabetes. Bioactive peptides that may be obtained from cereal grains, particularly wheat, oat, barley, and rice, were identified. Bioactive peptides that play a role in chronic disease prevention have been found primarily in legumes and dairy products; although research connecting cereal grains with potential bioactive peptide activity is limited. In this review, 4 cereal grains, wheat, oat, barley, and rice, were evaluated for bioactive peptide potential using the BIOPEP database. In addition, research information was compiled for each grain regarding evidence about the effect of their proteins in prevention of chronic diseases. All 4 grains showed high occurrence frequencies of angiotensin‐converting enzyme‐inhibitor peptides (A = 0.239 to 0.511), as well as of dipeptidyl peptidase‐inhibitor and antithrombotic, antioxidant, hypotensive, and opioid activity. Wheat and rice proteins had anticancer sequences present. Wheat and barley showed the greatest diversity and abundance of potential biological activity among the cereal proteins. Further research needs to be conducted to learn how these biologically active peptide sequences are released from cereal grains. This study supports the notion that cereal grains are a nutritious part of a healthy diet by preventing chronic diseases.     

市售国产酱油中大豆、小麦过敏原分析

为明确大豆和小麦发酵酱油中的残留过敏原,采用Tricine-十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）凝胶电泳,免疫印迹和间接性酶联免疫吸附测定（ELISA）等方法对从当地市场购得的14种酱油进行了分析,用来检测的四种血清包括实验室准备的大豆和小麦的兔血清免疫球蛋白G（immunoglobulin,IgG）以及从医院获得的大豆、小麦过敏病人血清免疫球蛋白E（IgE）。Tricine-SDS-PAGE结果表明,所有酱油样品都没有出现大豆和小麦蛋白的条带;免疫印迹结果表明,所有酱油样品中残留的大豆过敏原是β-伴大豆球蛋白的β亚基和大豆球蛋白的碱性亚基中的一种或两种,但小麦过敏原没有条带出现;酶联免疫结果表明,大豆过敏原含量与酱油酿造工艺与酱油等级有关,低盐固态酱油中检测到的大豆过敏原含量高于高盐稀态酱油,酱油的等级越高,所含过敏原含量相对越低。在所有酱油样品中,小麦过敏原含量极低甚至未检出。