辐照降低食物致敏性的研究进展

食物过敏是当前食品安全领域较为突出的问题,辐照技术作为解决食物脱敏的方法之一,引起了广泛的重视。本文综述了辐照降低食物过敏原致敏性的机理,并介绍了辐照脱敏研究的发展现状。     

电子束辐照对鲈鱼小清蛋白生化性质及抗原性的影响

为研究辐照对鲈鱼过敏原生化性质、抗原性及二级结构的影响，本试验采用0、3、5、7、9 kGy剂量电子束辐照鲈鱼小清蛋白溶液及冻干粉，测定其浓度、浊度、疏水性、分子量和抗原性的变化，以及二级结构的含量。结果表明，随着辐照剂量增大，小清蛋白冻干粉及溶液的浓度降低，疏水性提高，浊度增加，过敏条带变浅，免疫印迹条带变浅，小清蛋白与抗体的结合能力减弱，抗原性降低；α-螺旋及无规则卷曲比例升高，β-折叠及β-转角变化不明显，二级结构被破坏。综上，电子束辐照使小清蛋白生化性质及结构发生了变化，有效降低了小清蛋白的抗原性，同时发现液态小清蛋白较固态对辐照更敏感。本研究结果为鲈鱼及其制品辐照消敏研究提供了理论依据。     

食物蛋白致敏成分检测技术研究进展

食物过敏是指所摄入的食物中某种组成成分(主要为蛋白质)作为抗原诱导机体产生免疫应答而发生的一种变态反应疾病。食物致敏蛋白的快速高效检出已成为目前食品行业关注的重点。本文介绍了食物致敏原致敏机制,体内、体内检测技术的最新研究进展,并对各种检测技术的优缺点进行了深入分析。在此基础上,对食物蛋白致敏成分检测技术的发展趋势进行了展望,以期为致敏蛋白的深入研究提供参考。     

电子束辐照对花生过敏原免疫原性及生化性质影响的研究

研究了电子束辐照降低花生过敏原免疫原性的效果及辐照对花生生化性质的影响。选择2、4、6、8、10、15和20kGy剂量的电子束对花生过敏原液、脱脂花生粉进行辐照处理,辐照后花生主要过敏原(Ara h 1, Ara h 2, Ara h 3)蛋白分子质量的变化通过SDS-聚丙烯酰胺凝胶电泳测定,免疫原性的变化通过免疫印迹和间接竞争ELISA法测定;辐照后花生过敏原溶液的浓度、浊度及疏水性的变化通过紫外分光光度计和荧光光度计分别进行测定。结果表明,花生过敏原在溶液状态比固体状态对辐照更为敏感。当辐照剂量低于10kGy时处理的过敏原液的免疫原性稍有增强,剂量大于10kGy时免疫原性降低,剂量为20kGy时过敏原液的IC₅₀值是未处理的11倍。辐照使过敏液的浓度和浊度随着剂量的加大而增加,疏水性与对照组相比增强,但当剂量大于15kGy时降低。电子束辐照改变了过敏原的生化性质,降低了其免疫原性,比较而言,辐照对液体状态下过敏原的影响更显著。     

辐照对虾过敏原生化性质的影响

研究了以0、3、57、1、0kGy的辐照处理对虾过敏原的生化性质的影响。结果表明虾过敏原(Pen a1)提取液经辐照处理后,过敏原蛋白质的结构发生了变化,浊度和疏水性增加。并发现Pen a 1的溶液状态要比固体状态及活体状态对辐照处理更敏感。     

~(60)Co-γ辐照对花生过敏原Ara h 2蛋白构象及致敏活性的影响

为探讨辐照处理对花生Ara h 2蛋白结构与致敏活性的影响,采用不同剂量~(60)Co-γ辐照处理分离纯化所得到的花生过敏原Ara h 2蛋白,结合紫外扫描光谱、圆二色谱(CD)和聚丙烯酰胺凝胶电泳(SDS-PAGE)评估辐照处理后Ara h 2蛋白的结构变化,并用免疫印迹法和间接酶联免疫吸附法检测辐照处理后Ara h 2的抗原性变化。结果表明,~(60)Co-γ辐照处理可以显著改变花生Ara h 2蛋白的构象,使其降解、发生交联。随着辐照剂量的增大,Ara h 2蛋白与抗体的结合能力呈逐渐下降趋势,且与蛋白紫外吸光度的增强和α-螺旋含量的降低呈现良好的相关性。当辐照剂量为10 kGy时,可基本破坏Ara h 2蛋白的结构和免疫活性。~(60)Co-γ辐照处理可以有效降低花生过敏原Ara h 2蛋白的致敏性,这为花生脱敏技术的研究提供了新思路。     

60Co-γ辐照对花生过敏原Ara h 2蛋白构象及致敏活性的影响

为探讨辐照处理对花生Ara h 2蛋白结构与致敏活性的影响,采用不同剂量⁶⁰Co-γ辐照处理分离纯化所得到的花生过敏原Ara h 2蛋白,结合紫外扫描光谱、圆二色谱(CD)和聚丙烯酰胺凝胶电泳(SDS-PAGE)评估辐照处理后Ara h 2蛋白的结构变化,并用免疫印迹法和间接酶联免疫吸附法检测辐照处理后Ara h 2的抗原性变化。结果表明,⁶⁰Co-γ辐照处理可以显著改变花生Ara h 2蛋白的构象,使其降解、发生交联。随着辐照剂量的增大,Ara h 2蛋白与抗体的结合能力呈逐渐下降趋势,且与蛋白紫外吸光度的增强和α-螺旋含量的降低呈现良好的相关性。当辐照剂量为10 kGy时,可基本破坏 Ara h 2 蛋白的结构和免疫活性。⁶⁰Co-γ辐照处理可以有效降低花生过敏原 Ara h 2 蛋白的致敏性,这为花生脱敏技术的研究提供了新思路。     

辐照降解技术应用及影响因素分析

辐照降解技术作为辐照技术的一个分支,近年来获得了较快的发展。本文概述了辐照降解技术在减少动物源性食品中兽药残留、植物源性产品辐照降解加工、环境污染治理方面的应用现状。并就辐照降解技术的影响因素、机制和辐解产物的分析方法等内容加以综述。     

电子束辐照技术在生命科学中的应用

目前,辐照加工技术已在生命科学的各领域得到了广泛应用。本文简要概述了电子束辐照技术在食品加工与贮藏、医药卫生、诱变育种、植物检疫、化学残留物及过敏原降解等领域中的应用,旨在促进电子束辐照技术在生命科学中的应用,加快辐照加工行业发展,提高经济和社会效益。     

加工方式对非发酵面团小麦醇溶蛋白致敏性的影响

该研究探究了热加工(水煮、烘烤、微波、高温高压)、冷处理(液氮、速冻机速冻)和非热加工(超高静压、辐照、脉冲强光、臭氧和超声波)处理对非发酵面团小麦醇溶蛋白致敏性的影响。利用SDS-PAGE和双抗体夹心ELISA法研究各种加工处理后非发酵面团小麦醇溶蛋白的分子量和致敏性变化。结果表明:200和300 MPa的超高静压处理后,非发酵面团小麦醇溶蛋白的致敏性显著增加(P0.05),均增至125%左右;水煮、微波、高温高压、烘烤、液氮、速冻机处理、超高静压250MPa、辐照(7、13kGy)、臭氧熏蒸、脉冲强光和超声波处理均能显著降低非发酵面团小麦醇溶蛋白的致敏性(P0.05),其中以水煮、高温高压、液氮、臭氧和脉冲强光(PL-1)处理的脱敏效果最显著(P0.01),均降至60%左右。由此可知,加工方式能够显著影响非发酵面团小麦醇溶蛋白的致敏性,可作为食品中过敏原安全控制的有效手段,为脱敏食品的生产提供有效参考。进一步研究需要结合其他体内试验的评估,特别是小麦易敏人群的临床试验。     

Digestibility of food allergens and nonallergenic proteins in simulated gastric fluid and simulated intestinal fluid-a comparative study

Information on the comparative digestibility of food allergens and nonallergenic proteins is crucial when stability to digestion is to be used as a criterion to assess the allergenic potential of novel proteins. In this work, we compared the digestive stability of a number of food allergens and proteins of unproven allergenicity and examined whether allergens possess a higher stability than nonallergenic proteins of similar cellular functions, and whether there is a correlation between protein digestibility and allergenicity. The stability of groups of storage proteins, plant lectins, contractile proteins, and enzymes, both allergens and proteins with unproven allergenicity, in a standard simulated gastric fluid and a standard simulated intestinal fluid was measured. Food allergens were not necessarily more resistant to digestion than nonallergenic proteins. There was not a clear relationship between digestibility measured in vitro and protein allergenicity.     

Detecting potential IgE-reactive sites on food proteins using a sequence and structure database, SDAP-food

The high incidence of food allergies, including oral allergy syndrome, represent major considerations when introducing new crops and foods. A new structural database of allergenic proteins, SDAP-Food, http://fermi.utmb.edu/SDAP/, has been developed to aid in predicting the IgE-binding potential of novel food proteins and cross-reactivities among known allergens. The site is designed to facilitate the first steps of a decision tree approach to determine the allergenicity of a given protein, based on the sequence and structural similarity to known allergens and their IgE binding sites. Immunological tests can then be used to confirm the predictions. A hierarchical procedure for identifying potential allergens, using a physical property-based sequence similarity index, has been designed to identify regions that resemble known IgE binding sites. As an example, SDAP tools were used to find food allergen sequences similar to an IgE binding site of the Jun a 3 allergen from mountain cedar pollen. The SDAP sequence similarity search matched the Jun a 3 epitope to regions in several food allergens, including cherry (Pru av 2), apple (Mal d 2) and pepper (Cap a 1), which are, like Jun a 3, members of the plant pathogenesis-related (PR-5) protein family. Homology modeling, using our EXDIS/DIAMOD/FANTOM program suite, indicated a similar surface location and structure for the potential epitope region on all of these allergens. The quantitative approach presented here can be used as part of a screening process for potential allergenicity of recombinant food products.     

试论广西农产品、食品辐照加工业的发展前景

介绍了国内外辐照食品加工业发展概貌 ,展望了广西农产品、食品辐照加工业的发展前景。     

Development of a real-time PCR and a sandwich ELISA for detection of potentially allergenic trace amounts of peanut (Arachis hypogaea) in processed foods

Hidden allergens in food products are, especially for peanut-allergic consumers, a serious problem because even low amounts (approximately 200 microg) of peanut can elicit allergic reactions. Undeclared peanut traces can be found in processed food products, because contaminations with peanut during production processes are frequent. To minimize the risk of such cross-contaminations, it is necessary to develop sensitive analytical methods for the detection of hidden allergens in foods. For this approach we developed two peanut-specific assays based on the detection of peanut protein by specific antibodies (sandwich ELISA) and by the detection of peanut-specific DNA (part of the coding region of Ara h 2) by a real-time PCR. Both tests did not show any cross-reactivity with 22 common food ingredients (cereals, nuts, legumes), and the limit of detection is <10 ppm peanut in processed foods. Thirty-three random samples of food products were tested for the presence of peanut to compare both assay types with each other and to evaluate the percentage of foods on the German market that are contaminated with peanut traces. We found that four products (13.3%) without peanut in the list of ingredients contained peanut protein in a range from 1 to 74 ppm peanut protein and that the results of both tests correlated well. The real-time PCR was able to detect one more positive sample than the sandwich ELISA. In conclusion, both assays are sensitive and specific tools for the detection of hidden allergens in processed foods.     

Disulfide Proteome Analysis of Buckwheat Seeds to Screen Putative Allergens

Accumulating evidence suggests a correlation between disulfide bonding and the allergenicity of proteins. Also, a significant characteristic of most food allergens is that they are stable to proteases. We sought to identify putative allergens of buckwheat seed comprehensively by combining a disulfide proteome technique with an in vitro digestibility test. First, a dilute acetic acid fraction of buckwheat seed was found to be rich in disulfide proteins. Internal amino acid sequence analyses of these proteins showed that most of them were known allergens or putative allergens sharing high amino acid sequence similarities to known allergens. Next, the fraction was subjected to in vitro protease digestion, which revealed relatively large fragments that were resistant to prolonged enzymatic digestion. These protease‐resistant fragments contained disulfide bonds that should have protected the potential enzyme cleavage sites by forming compact structures. These results confirm and extend our knowledge of the correlations among the disulfide bonding of proteins, their protease stability, and their allergenicity. Also, these observations suggest a new strategy to identify putative allergens by proteomic approaches as well as to mitigate them.     

同位素指纹分析技术在食品产地溯源中的应用进展

食品的产地溯源有利于保护原产地，保护地区名牌，保护特色产品，确保公平竞争，增强消费者对食品安全的信心，并能有效防止食源性病源菌的扩散。同位素分析是用于食品产地溯源的有效技术之一，而且对食品原料如酒、饮料、乳品、肉品、谷物等普遍适用。本文重点介绍了同位素溯源技术的基本原理，几种常用同位素在自然界中的变化机理，以及它们在不同食品溯源中的研究现状。推动同位素溯源技术在食品安全领域的研究与应用，促进食品追溯制度的建立与完善。     

Food Security in India: The Challenge of Food Production and Distribution

Food security in India is adversely affected by several abiotic, biotic, and sociopolitical situations. The current position may worsen in the future if timely and appropriate actions are not planned and executed. The pressure of human population and land for cultivation, climate change, government policies of public distribution and marketing of food grains, and lack of a participatory approach—all are contributing to slow down the availability of foods. Also, crop productivity seems to be very much unsustainable. The situation has to be remedied by all possible means and citizens must be assured of food security. This review summarizes several strategies for crop production and food distribution and emphasizes the need for a second Green Revolution.