Development of a Biological Assay to Determine the Allergenic Potential of Foods

Food allergies represent a risk for many people in industrialized countries. Unrecognizable allergenic proteins of foodstuffs may be present as ingredients that are not labeled or as unknown cross-contamination. Such hidden allergens can cause severe reactions in allergics, even at minute quantities, sometimes with fatal outcome. For the verification of the presence of allergenic food constituents, analytical methods such as ELISA and PCR have been developed. However, these tests cannot measure allergenic potential. For this reason, a test system that measures the biological activity of allergens has been developed. It is based on the cellular mechanisms of the type I allergy. Rat basophilic leukemia cells (RBL-2H3) were transfected with the genes of the human high affinity receptor for IgE. The resulting cell line expressed the human receptor α-chain and could bind allergenspecific IgE from allergic subjects, in contrast to the parent cell line. After cross-linking of receptor-bound, allergen-specific human IgE by allergens, the cells released measurable inflammatory mediators. These cells were used for the analysis of a variety of allergen extracts, including extracts prepared from foods containing allergenic hazelnut and peanut. The comparative validation with existing ELISA and PCR for hazelnut and peanut demonstrated similar sensitivity and specificity. The established cell line will be a novel tool in the detection of allergens in complex mixtures, especially to address the issue of their allergenic potential, which cannot be accomplished by classical analytical methods. This will add valuable information about the allergenic potential of food constituents to the risk assessment of foods.

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Zusammenfassung. Allergene Lebensmittelbestandteile stellen für viele Nahrungsmittelallergiker in industrialisierten L?ndern ein reales Gesundheitsrisiko dar, wenn sie als nicht deklarierte Zutaten oder unerkannte Kontaminationen in Lebensmitteln enthalten sind. Diese so genannten versteckten Allergene k?nnen, teilweise in geringsten Mengen, schwere Reaktion bei sensibilisierten Personen auszul?sen, manchmal auch mit t?dlichem Ausgang. Zum Nachweis allergener Lebensmittelbestandteile wurden bereits verschiedene analytische Methoden, wie z. B. ELISA- und PCR-Verfahren, entwickelt. Allerdings sind diese Methoden nicht in der Lage, das allergene Potenzial solcher Bestandteile zu erfassen. Um jedoch die biologische Aktivit?t von Allergenen messen zu k?nnen wurde ein Testsystem entwickelt, das auf dem Mechanismus der Typ-I Allergie basiert. Dazu wurden basophile Leuk?miezellen der Ratte mit den Genen des humanen hochaffinen Rezeptors für IgE transfiziert. Die daraus resultierende Zelllinie exprimiert einen chim?ren Rezeptor (mit der IgE-bindenden humanen α-Kette) stabil auf ihrer Oberfl?che und ist somit in der Lage, auch allergenspezifisches IgE aus Allergikerseren zu binden, was mit der Ausgangszelllinie nicht m?glich ist. Die Vernetzung des rezeptorgebundenen IgEs durch das Allergen führt in der Folge zur Freisetzung entzündungsausl?sender Mediatoren, die im Zellkulturüberstand gemessen werden k?nnen. Diese transfizierte Zelllinie wurde zur Analyse einer Vielzahl von Allergenextrakten eingesetzt, darunter auch Extrakte von Lebensmitteln, die Haselnuss- oder Erdnussallergene enthielten. Der Vergleich des biologischen Testsystems mit den ELISA- und PCR-Verfahren für Hasel- und Erdnuss ergab eine ?hnliche Sensitivit?t und Spezifit?t. Die etablierte Zelllinie ist ein neues, wertvolles Hilfsmittel für den Nachweis von Allergenen in komplexen, zusammengesetzten Lebensmitteln und im Besonderen zur Erfassung des allergenen Potenzials solcher Nahrungsmittelbestandteile. Somit kann dieses neue Nachweisverfahren helfen, zus?tzliche wichtige Informationen für die Risikobewertung von Lebensmitteln zu gewinnen.

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A Method to Determine Initial Freezing Point of Foods

An accurate initial freezing point T_sh is required for reliable analysis of a food freezing or thawing process. Two previous formulae for accurately estimating enthalpies, one for temperatures above T_sh and another below T_sh, were used for this development. The estimation of T_sh was based on the mathematical formulation of continuity in food enthalpies estimated by both formulae at T_sh. The method was validated by estimating T_sh values of aqueous solutions of sucrose and NaCl at different solutions. There was fair agreement in the T_sh values of fresh fruit and vegetables, lean beef meat and lean fish meat estimated by the proposed and a previous method. One potential advantage of our new method was the direct estimation of T_sh through analysis of food enthalpies collected at different temperatures.     

食品中荧光假单胞菌聚合酶链式反应检测体系的建立和评价

建立用聚合酶链式反应(polymerase chain reaction,PCR)检测食品中荧光假单胞菌的方法。分别针对16～23S rRNA基因间隔区序列、gyrB基因以及通过生物信息学方法发掘到的4个种特异性基因设计6对检测引物,通过初步特异性实验,筛选出一对种特异性最佳的引物。最终建立以gyrB基因为检测靶点的PCR扩增体系,并对体系进行系统评价。结果表明:该方法可特异检测荧光假单胞菌的存在,纯DNA检测灵敏度为14.9fg/μL(2～3拷贝/μL),纯培养物检测灵敏度为2.8×102CFU/mL。豆奶样品经15h充分增菌可提高检测灵敏度至0.28CFU/25g。     

寿命可靠性计算在食品货架期分析中的初步应用

以市售灭菌乳为研究对象,应用Weibull模型通过对食品非感官指标的分析,预测食品的货架期。灭菌乳分别在25、30、35、40℃环境下恒温储藏45d,并定期随机抽样进行感官检验和测定酸度。应用Weibull hazard analysis(WHA)方法分析非感官试验数据来预测样品货架期,并进行了寿命可靠性分析。     

动物性食品中磺胺二甲嘧啶快速检测方法

根据竞争抑制免疫层析原理,应用胶体金免疫层析技术进行磺胺二甲嘧啶在鸡肉和鲫鱼中的残留检测研究。磺胺二甲嘧啶半抗原-OVA和羊抗兔二抗分别作为检测带(T线)和质控带(C线)包被在硝酸纤维素膜上,金标抗体喷涂在玻璃纤维垫上,制成免疫层析快速检测试纸条。所建立的检测体系对标准溶液的灵敏度达到1μg/L。成功检测了鸡肉和鲫鱼中的磺胺二甲嘧啶残留。该方法灵敏度高,所用试剂无毒、无污染,无需借助仪器,样品前处理简便,快速,检测过程可在10 min内完成,可以作为现场快速检测动物源性食品中磺胺二甲嘧啶残留的有效手段。     

金针菇多糖生物活性及功能性食品开发

概述了金针菇多糖（ Flammulina velutipes Polysaccharides, FVP）保湿美容、抗氧化、降血脂、增强免疫等生物活性,讨论了金针菇多糖功能性食品的开发,并对金针菇多糖的未来发展进行了展望。     

A Simple and Fast HPLC Method to Determine Lycopene in Foods

Carotenoids, among which lycopene—the principal pigment found in tomatoes—are lipophilic compounds which play a very important role in human health and nutrition. They are also recognised as strong antioxidants due to their ability to trap singlet oxygen and eliminate the peroxyl radical. The availability of reliable information on lycopene content of foods is essential both for the evaluation of diet and for epidemiological research relating the intake of lycopene. This paper describes a simple and fast HPLC/UV method for lycopene determination in a wide range of food products. All-E-lycopene together with its Z isomers were eluted isocratically using a carotenoid C30 reversed-phase column. The in-house validated HPLC method had a limit of quantification of 60 ng lycopene/g product and high precision and accuracy. The analytical method was successfully applied to several food products such as raw vegetables and fruits and also processed foods. Tomato and tomato-containing products contained the highest amounts of lycopene. While raw foods and minimally processed foods contained above 94% of all-E-lycopene, processed foods (such as soups, pasta sauces, pizza and cheese) contained from 76% to 87% of all-E-lycopene.     

海洋生物资源在军用功能性食品开发中的应用

海洋蕴藏着丰富的生物资源,利用海洋生物资源研究与开发军用功能性食品成为热点。本文详细介绍了海洋生物资源在抗辐射、改善脑功能以及抗疲劳军用功能性食品中的应用,为研究和开发提供参考。     

基于多重连接探针扩增技术的食品中六重过敏原成分检测

基于多重连接探针扩增（multiplex ligation-dependent probe amplification,MLPA）技术建立了一种六重过敏原成分检测方法,可实现食品中大豆、芝麻、花生、杏仁、榛子和核桃6种成分的同时检测。选取多拷贝ITS基因为靶标基因,设计并合成6组特异性杂交探针。探针经杂交、连接和聚合酶链式反应得到扩增片段,经毛细管电泳分析扩增片段大小可明确区分6种过敏原成分。该体系经20余种相关植物、动物及微生物DNA验证显示其特异性良好,经模拟参考样品验证其检出限为5 mg/kg。30份不同种类市售食品MLPA检测结果表明,该方法性能满足实际样品的过敏原的多重检测。因此,本研究建立的基于MLPA技术的六重过敏原检测方法特异性强、灵敏度高,能够为食品过敏原评估、标识管理和风险控制提供技术支撑。     

食品中单核细胞增生李斯特菌DNA环介导恒温扩增快速检测方法的建立

基于单核细胞增生李斯特菌胞壁质水解酶iap基因,设计两对特异性引物,利用DNA环介导恒温扩增(loop-mediated isothermal amplification,LAMP)技术,以扩增副产物焦磷酸镁实时浊度为判定标准,建立食品中单核细胞增生李斯特菌LAMP快速检测方法。结果显示,本LAMP方法特异性强,经过对29株细菌进行检测,所试单核细胞增生李斯特菌均为LAMP阳性,其他菌株为阴性;本LAMP方法对单核细胞增生李斯特菌纯培养菌的检测灵敏度为8CFU/管,对污染食品中单核细胞增生李斯特菌的检测灵敏度为12CFU/管。本研究建立的LAMP检测方法简便快速、结果判断直观。     

Development of a Highly Sensitive Competitive Indirect Enzyme-Linked Immunosorbent Assay for Detection of Acrylamide in Foods and Water

Acrylamide (AA) has been classified as a probable human carcinogen and forms in certain foods, particularly plant-based foods that are rich in carbohydrates and low in proteins, during processing or cooking at high temperatures. In this study, polyclonal antibodies were raised against a hapten derived from acrylamide and 3-mercaptobenzoic acid (3-MBA). An indirect competitive enzyme-linked immunosorbent assay was developed to rapidly quantify AA in complex food matrices and water. The assay was very specific to the AA-3-MBA derivative and showed no cross-reactivity to asparagine, the main precursor of AA formation in foods, aspartic acid, AA, or 3-MBA. The assay was very sensitive with a limit of detection of 5.0 ng/g in model for food matrices to 0.1 μg/L in water. Good recoveries for AA were observed in all matrices tested, and the results using this method were comparable to those obtained from mass spectrometry methods including Food Analysis Performance Assessment Scheme control samples and results for different food products.     

发展绿色食品、有机食品、丰富食物构成

绿色食品、有机食品是指经专门机构认定、许可使用绿色食品标志和有机食品标志的无污染的安全、优质、营养类食品。本文从绿色食品、有机食品的由来，绿色食品的定义、标准、标志，有机食品生产、加工的要求，绿色食品工程作了论述。并就绿色食品、有机食品的前景，市场潜力和开发深度符合现代农业和食品工业可持续发展的方向，符合世界进步潮流，得以维持自然、经济、社会的和谐、持续发展，逐步实现经济效益、社会效益、生态效益的良性循环作了阐述。     

黄曲霉毒素B1金标检测体系建立过程中的影响因素

详细研究了纳米金标记免疫检测体系建立过程中的影响因素，包括检测带的信号强度、封闭试剂，纳米金探针的浓度、包被试剂A和B的浓度、纳米金溶胶的颗粒尺寸，及检测过程中的化学体系等。通过参数优化，确立了建立快速、简易的金标试剂条检测方法的最佳条件。探针溶液中加入保护试剂K后，试剂条的稳定性有明显的提高，常温下试剂条保存期可达120d（信噪比保留70％以上）。     

蚕蛹蛋白的生物活性和过敏特性的研究进展

具有高营养价值的昆虫一直以来都是我国优质的食物来源之一。蚕蛹是家蚕业的重要副产物之一,其在东亚各国作为食物和饲料已有十分悠久的历史。蚕蛹含有丰富的蛋白质、脂质、矿物质和维生素,具有十分重要的营养价值和经济价值。蚕蛹的应用范围十分广泛,我国有许多保健品、药物还有食物添加剂中都有蚕蛹的成分。蚕蛹蛋白及其水解物具有多种生物活性,具备一定的开发潜力。然而,蚕蛹也能导致轻度甚至严重的过敏反应,这些不良反应极大的限制了蚕蛹在全国范围内的普及程度。因此该研究综述了蚕蛹蛋白的生物活性和过敏特性,以期为蚕蛹的开发与利用提供一定的参考。     

Development of a Mathematical Model for MAP Systems Applied to Nonrespiring Foods

ABSTRACT A mathematical model for gas diffusion processes in MAP systems was built. The model was applied to MAP systems containing CO₂, O₂, and N₂ with nonrespiring foods. The validation study was done with gelatin, and simulation trials were carried out utilizing Hake (Merluccius australis) fillets. Experimental results confirmed the proposed mathematical model and its numerical solution. The prediction errors obtained in the validation study were under 5%; the same was true with the simulation trials whose errors were always lower than 5%. Both the simulation trials and validation study demonstrated that MAP systems reach equilibrium after a short period of time if film permeability is low.     

胶体金免疫层析技术测定食品中黄原胶

目的:建立一种简便实用的胶体金免疫层析检测新方法,用于食品中黄原胶的快速筛查。方法:用黄原胶抗原标准品免疫新西兰大白兔,制备得到高效价的抗黄原胶多克隆抗体;采用柠檬酸三钠还原法制备胶体金,并将其与抗黄原胶多克隆抗体标记制得金标抗体;在硝酸纤维素膜检测线上,预包被黄原胶标准抗原,质控线上包被羊抗兔IgG,采用竞争法,制成黄原胶胶体金免疫层析检测试纸条,并对试纸条的特异性、敏感性和稳定性进行了试验。结果:该试纸条检测样品的敏感性为3g/kg。结论:研制出黄原胶胶体金免疫层析试纸条及其检测方法,该方法敏感性高、特异性强、操作简便,5min可出检测结果,可用于现场大量样品的快速检测。     

Evaluation of Enzyme-Linked lmmunosorbent Assay for Detection of Molds in Foods

Enzyme-linked immunosorbent assay (ELISA) was used to detect Al-ternaria alternata, Geotrichum candidum, and Rhizopus stolonifer in processed fruit and vegetable products, bread, and cottage cheese. ELISA readings correlated with the amount of added mold and generally low backgrounds were obtained from control food samples. For bread and cottage cheese, the dilution factor affected the efficiency of the assay. Both viable and nonviable molds could be detected. The ELISA method gave results that correlated with those of the Howard mold count. The assay was relatively specific, although cross reaction was observed among some molds. The major antigenic components were polysaccharide in nature.     

Detection of Walnut Residues in Foods Using an Enzyme-Linked Immunosorbent Assay

ABSTRACT:  Tree nuts, including walnuts, can be responsible for allergic reactions. Food manufacturers have the responsibility to declare the presence of walnuts on packaged foods even when trace residues may be present from the use of shared equipment or the adventitious contamination of ingredients. The aim of this study was to develop a rapid, sensitive, and specific enzyme-linked immunosorbent assay (ELISA) method for the detection of walnut protein residues. Mixtures of raw and roasted English walnuts of several varieties were defatted, powdered, and used as separate antigens in sheep and New Zealand white rabbits. An ELISA was developed using the sheep antiroasted walnut serum as the capture reagent and rabbit antiroasted walnut serum as the detector reagent followed by addition of commercial goat anti-rabbit IgG antibody labeled with alkaline phosphatase and subsequent substrate addition. The performance of the ELISA was validated by testing known amounts of walnut (0 to 100 ppm) either spiked into or manufactured into milk chocolate, cookies, muffins, or ice cream. Recoveries of 1 to 100 ppm walnut-in-chocolate ranged from 71.6% to 119%± 7% to 16.5%. The walnut ELISA has a detection limit of 1 ppm (1 μg/g) walnut in several food matrices. Substantial cross-reactivity was observed with pecan while minimal cross-reactivity was noted for hazelnut, mustard, mace, and poppy seed among almost 100 foods and food ingredients tested. This walnut ELISA can be used to detect undeclared walnut residues in foods and ingredients and as a tool to validate the effectiveness of allergen control programs for walnuts.