Effects of daily food processing on allergenicity

Daily food processing has the potential to alter the allergenicity of foods due to modification of the physico-chemical properties of proteins. The degree of such modifications depends on factors such as processing conditions, type of food considered, allergenic content, etc. The impact of daily food processing like boiling, roasting, frying or baking on food allergenicity have been extensively studied. The influence of other thermal treatments such as microwave heating or pressure cooking on allergenicity has also been analyzed. Non-thermal treatment such as peeling impacts on the allergenic content of certain foods such as fruits. In this review, we give an updated overview of the effects of daily processing treatments on the allergenicity of a wide variety of foods. The different variables that contribute to the modification of food allergenicity due to processing are also reviewed and discussed.     

Allergenicity of peanut allergens and its dependence on the structure

Food allergies are a global food safety problem. Peanut allergies are common due, in part, to their popular utilization in the food industry. Peanut allergy is typically an immunoglobulin E-mediated reaction, and peanuts contain 17 allergens belonging to different families in peanut. In this review, we first introduce the mechanisms and management of peanut allergy, followed by the basic structures of associated allergens. Subsequently, we summarize methods of epitope localization for peanut allergens. These methods can be instrumental in speeding up the discovery of allergenicity-dependent structures. Many attempts have been made to decrease the allergenicity of peanuts. The structures of hypoallergens, which are manufactured during processing, were analyzed to strengthen the desensitization process and allergen immunotherapy. The identification of conformational epitopes is the bottleneck in both peanut and food allergies. Further, the identification and modification of such epitopes will lead to improved strategies for managing and preventing peanut allergy. Combining traditional wet chemistry research with structure simulation studies will help in the epitopes’ localization.     

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis,Diagnosis, Management,and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega‐3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life‐threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the “major allergens.” Act d 1 and Act d 2 are ripening‐related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.     

Potential Utility of High‐Pressure Processing to Address the Risk of Food Allergen Concerns

High‐pressure processing (HPP) technology is a novel, nonthermal processing technology for food. This special processing method can inactivate microorganisms and enzymes in food at room temperature using ultra‐high pressures of above 100 MPa, while the original flavor and nutritional value of the food are maintained, with an extended refrigerated shelf‐life of the food in distribution. In recent years, because of the rising prevalence of food allergies, many researchers have actively sought processing methods that reduce the allergenicity of food allergens. This study describes the effects of the current HPP technology on allergen activity. Our main goal was to provide an overview of the current research achievements of the application of HPP to eliminate the allergenicity of various foods, including legumes, grains, seafood, meat, dairy products, fruits, and vegetables. In addition, the processing parameters, principles, and mechanisms of HPP for allergen destruction are discussed, such as the induction of protein denaturation, the change in protein conformation, allergen removal using the high‐pressure extraction technology, and the promotion of enzymatic hydrolysis to alter the sensitization of the allergens. In the future, the application of HPP technology as a pretreatment step for raw food materials may contribute to the development of food products with low or no allergenic ingredients, which then can effectively reduce the concern for consumers with allergies, reduce the risk of mistaken ingestion, and reduce the overall incidence of allergic reactions from food.     

乳酸菌降低过敏食物致敏性的研究进展

食物过敏的患病率在近几十年内急剧上升,越来越多的证据表明机体内微生物的生态失调是引起食物过敏的主要原因,因此乳酸菌等益生菌对过敏症状的潜在预防和治疗效果引起了人们的广泛关注。大量研究表明乳酸菌不仅能够通过发酵降低食物过敏原的致敏性,而且有可能通过调节肠道菌群的平衡在宿主免疫系统的发育和调节中发挥作用,从而改变过敏性疾病的发病风险。本文综述了乳酸菌的分类和生物特性,乳酸菌发酵在降低牛奶、大豆、花生、小麦等主要食物过敏原中发挥的作用,乳酸菌发挥免疫调节作用的主要机制,包括改变抗原递呈细胞的表型、调节Th1/Th2平衡、诱导调节性T细胞、增强肠道屏障功能。以期通过乳酸菌及其发酵作用达到预防和/或治疗食物过敏的效果,为乳酸菌的研究及应用提供参考。     

辐射处理对水果品质影响的研究进展

为给水果辐射保鲜的研究与应用提供参考,本文综述了辐照技术对水果生理代谢、感官品质、营养成分及加工品质的影响。提出应加强电子束对水果保鲜机理及辐照工艺、辐射降解果品中农药残留的机理和工艺研究,探讨辐照技术降低水果致敏性的可行性。应根据不同种类水果的生理特点和贮藏特性,将辐射保鲜与其他保鲜技术有机结合起来,以降低辐照成本、提高保鲜效果。     

Why are some proteins allergenic? Implications for biotechnology

In recent years, a number of agricultural crops have been developed with recombinant DNA technology. Because the transferred genes code for proteins that are ordinarily not present in these particular foods, there is concern about the potential allergenicity of these new crop varieties. Foods contain many proteins; however, only a small fraction are allergens. Although the structural properties of proteins that cause allergic reactions have not been characterized completely, known food allergens in general have molecular weights between 10 and 70 kDa, stimulate the immune response (induce the production of allergen‐specific IgE), and are stable molecules that are resistant to processing, cooking, and digestion. Although any type of food is potentially allergenic, the majority of food allergies are caused by a small group of foods (cows’ milk, nuts, legumes, eggs, seafood). Cross‐reactivities occur within a given food group and between foods and seemingly unrelated proteins.

Even though most transgenic foods are considered safe, biotechnological manipulation can affect crop allergenicity. The safety evaluation of transgenic foods is relatively easy when the allergenicity of the gene sources are known. The recombinant food can be assayed using traditional in vitro inhibition assays. Recently, reduced allergen content of biotechnologically altered rice was shown. In contrast, increased allergenicity was demonstrated in transgenic soybeans after a methionine‐ and cystine‐rich protein from Brazil nuts, identified as a major Brazil nut allergen, was expressed in soybean to increase its content of sulfur‐rich amino acids. The most difficult issue regarding transgenic food allergenicity is the effect of transfer of proteins of unknown allergenicity. The challenge is to determine whether these proteins are allergenic as there is no generally accepted, established, definitive procedure to define or predict a protein's allergenicity. Comparing the structures of the transferred protein with known allergens and allergen epitopes could be one approach. Additionally, Th‐2 cell stimulation, the production of IL‐4, and IgE antibody induction in animal models may help to evaluate the potential allergenicity of a protein.

In conclusion, there is no evidence that recombinant proteins in newly developed foods are more allergenic than traditional proteins. The evidence suggests that the vast majority of these proteins will be completely safe for the consumer. The concern is that if a few transgenic foods cause serious allergic reactions, this could undermine the public's confidence in such products. It is essential that proper guidelines are established and tests are developed to assure that this will not occur.     

大豆主要过敏原及其脱敏方法的研究进展

大豆是引起食物过敏最常见的过敏原食物之一,如何降低大豆的致敏性,保证大豆食品的安全,已成为食品安全领域的一项重要课题。大豆中的过敏原蛋白很多,大致可分为种子储藏蛋白、结构蛋白和防御相关蛋白。其中7S球蛋白组分中的Gly m Bd 30 K和Gly m Bd 28 K,β-伴大豆球蛋白中的Gly m Bd 60K是3种主要的过敏原。近几年来,以热加工法、酶处理法、超高压法和基因工程法等为代表的大豆脱敏技术研究取得了很多新进展。其中,热加工法与酶处理法已经在食品工业中广泛应用。超高压法作为一种新的大豆脱敏技术,由于它对大豆的营养价值和风味影响较小,越来越受到食品工业的关注,具有潜在的应用前景。基因工程法则是食品脱敏的新技术,它可以消除食物原料过敏原性,但基因食品的安全性仍饱受争议,能否实际应用于脱敏仍待进一步研究。     

从过敏原危害评估食物过敏风险

随着全球食物过敏发生率的逐年升高,食物过敏性疾病已成为人们日益关注的食品安全和公共卫生问题。本文介绍了食物过敏原特性、致敏机制、临床表现、常见致敏食物及主要暴露来源等内容,概括了食物过敏原阈值及参考剂量的制定方法和最新调整情况,并总结了目前国际上公认的几种食物过敏原的风险评估方法,以期对下一步开展我国人群食物过敏风险评估提供理论依据。     

食用芒果过敏的研究进展

芒果是我国亚热带地区重要经济作物,含有多种功能性成分,然而大部分人群在接触或食用芒果后会出现不同程度的过敏临床反应。本文简单介绍食用芒果导致的过敏反应,包括接触性皮炎、口腔过敏症状、交叉过敏等,并详细阐述了芒果导致过敏现象的两种途径,以及不同过敏原物质、反应类型和发病人体的免疫途径。根据过敏原Allergome数据库(http://www.allergome.org/)分析得到芒果中所含有的9种主要的过敏原,并对其中2种过敏原蛋白,即抑制蛋白和几丁质酶进行了结构域的分析。通过对芒果过敏交叉反应的介绍,得到不同物种中的过敏蛋白氨基酸序列具有高度同源性,而这些同源性序列决定与免疫球蛋白E具有相同作用的表位。本文以期从分子水平上提供芒果低过敏品种培育的新途径和过敏防治的新思路。     

Impact of dietary factors and food processing on food allergy

Allergic reactions to food can significantly reduce the quality of life and even result in life‐threatening complications. In addition, the prevalence of food allergy has increased in the last decades in industrialized countries and the mechanisms underlying (increased) sensitization are still not fully understood. It is believed that the development and maintenance of oral tolerance to food antigens is a process actively mediated by the immune system and that this reaction is essential to inhibit sensitization. Ongoing research indicates that different dietary factors also may contribute to immune homeostasis and oral tolerance to food and that food processing modulates allergenicity. One of the major questions in food allergy research is therefore which impact nutrition and food processing may have on allergenicity of food and perhaps on sensitization. We summarize in this review the different dietary factors that are believed to contribute to induction of oral tolerance and discuss the underlying mechanisms. In addition, the functional consequences of allergen modification will be emphasized in the second part as severity of allergic reactions and perhaps sensitization to food is influenced by structural modifications of food allergens.     

Food Allergens: Is There a Correlation between Stability to Digestion and Allergenicity?

Food allergy is a major health problem in the Western countries, affecting 3–8% of the population. It has not yet been established what makes a dietary protein a food allergen. Several characteristics have been proposed to be shared by food allergens. One of these is resistance to digestion. This paper reviews data from digestibility studies on purified food allergens and evaluates the predictive value of digestibility tests on the allergenic potential. We point out that food allergens do not necessarily resist digestion. We discuss how the choice of in vitro digestibility assay condition and the method used for detection of residual intact protein as well as fragments hereof may greatly influence the outcome as well as the interpretation of results. The finding that digests from food allergens may retain allergenicity, stresses the importance of using immunological assays for evaluating the allergenic potential of food allergen digestion products. Studies assessing the allergenicity of digestion products, by either IgE-binding, elicitation or sensitizing capacity, shows that digestion may abolish, decrease, have no effect, or even increase the allergenicity of food allergens. Therefore, the predictive value of the pepsin resistance test for assessing the allergenic potential of novel proteins can be questioned.     

Influence of processing and storage on the antioxidant activity of apple derivatives

The antioxidant activity of seven apple varieties was determined on fresh fruits and processed products (dried fruits and purees) and during storage. The antioxidant activity of apples correlated with the total phenol concentration but not with ascorbic acid concentration. Apple derivatives showed a lower antioxidant activity than the counterparts of the fresh fruits and the occurrence of browning phenomena during processing resulted in lower antioxidant activity. Dried fruits showed higher antioxidant activity per gram of dried matter than fruit purees probably because of the lower total thermal effect of processing. The antioxidant activity of all products increased within the first month of storage, and then declined. The extent of early increase was related to the polyphenol content of the fruit. Packaging conditions further influenced the antioxidant activity increase during storage possibly by affecting the oxygen availability.     

Testing of a VIS-NIR System for the Monitoring of Long-Term Apple Storage

The development of diseases during long-term storage of apples is a well-known issue causing loss of product for warehouses. Non-destructive characterization of fruit can be helpful in order to reduce waste and maximize apple quality. The aim of this study was to evaluate the applicability of visible and near-infrared (VIS-NIR) spectroscopy to monitor and manage lots of apples during long-term storage in a cold room. A bench-top VIS-NIR apparatus (600–1200 nm) was used to classify apples from two different cultivars, Golden Delicious and Red Delicious, based on their total soluble solids content (TSS). The evolution of the originally created classes was analyzed during 7 months of storage by monitoring TSS and firmness (peak force and penetration energy), and the estimation ability of the VIS-NIR device was evaluated. The results indicate that the spectroscopic technique allows for an accurate estimation of chemical-physical parameters for non-destructive classification of apples in homogeneous lots. Regarding the estimation ability of the compact VIS-NIR spectrophotometer, the results show good prediction ability both for total soluble solids content and firmness indices. The use of the instrument for on-line selection and classification of fruits is therefore desirable. This can lead to better management of postharvest storage and the destination of lots, with a consequent reduction in fruit wastage. This approach is important to plan the opening sequence of storage rooms during the winter season, providing the market with the best available products all year round.     

The influence of organic/integrated production on the content of phenolic compounds in apple leaves and fruits in four different varieties over a 2‐year period

BACKGROUND: Phenolics in fruit may be influenced by the fruit type, cultivation conditions of a plant, climatic conditions, growing season, storage conditions, and industrial processing. The aim of this study was to compare single phenolic compounds, total phenolics and antioxidant capacity of four varieties of apple grown under organic and integrated conditions over a 2‐year period. RESULTS: Several different phenolic compounds belonging to the groups of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols and anthocyanins were quantified. The levels of all analysed groups of phenolics were higher (not always significantly) in the organically grown apple leaves and fruit than in the leaves or apples from integrated production. Leaves from organic trees had 10–20% higher content levels of total phenols than the leaves from trees in the integrated growing system. In both years, organic production affected the increase in the antioxidant activity of apple peel. Organic apples have higher total phenolic content than the integrated grown ones. CONCLUSION: Cultivation type had an important influence on the polyphenolic level and antioxidant capacity of the apple fruits and leaves. Apples from organic production showed a higher content of hydroxycinnamic acids, flavanols, dihydrochalcones, quercetins and total phenolics than apples from integrated cultivation. Copyright © 2010 Society of Chemical Industry     

Tomato allergy: impact of genotype and environmental factors on the biological response

BACKGROUND: Food allergies are increasing in the European population. At present the onset of symptoms can be avoided only by elimination of a particular fruit or vegetable from the diet. A new approach is to develop hypoallergenic food products. This study characterises the allergenic potential of tomatoes, considering cultivation conditions, developmental stages and genotypes, in order to identify hypoallergenic fruits. RESULTS: Patients with a history of tomato allergy were recruited for skin allergy tests. Tomatoes carrying distinct genotypes were grown under various cultivation conditions and harvested at different maturation stages. Cultivation conditions (nitrogen fertilisation, light exposure and plant nutrition) did not affect the skin reactivity in tomato‐allergic patients. However, skin reactivity was significantly lower when using green‐unripe compared with red‐ripe tomatoes and when using landrace cultivars compared with cultivars bred for use in organic horticulture. CONCLUSION: Depending on their genetic background and maturity level, some tomato cultivars elicit positive reactions in tomato‐allergic patients in the skin allergy test. This novel finding should pave the way for the development of tomatoes with reduced allergenicity to relieve sufferers of tomato allergy. Copyright © 2011 Society of Chemical Industry     

加工对鸡蛋过敏原的影响

卵类黏蛋白、卵白蛋白、卵转铁蛋白和溶菌酶是鸡蛋中的主要过敏原,适当的物理、化学和生物加工可以降低它们的致敏性。其中物理法生产的低致敏性蛋制品可供鸡蛋轻微过敏人群食用或作为免疫治疗药物;而化学和生物法制备的低过敏鸡蛋制品存在安全风险,它能否应用于生产,还有待进一步研究。另外,各种加工方法可以影响过敏原蛋白二硫键及高级结构甚至一级结构,从而导致该蛋白的致敏性发生变化。总之,加工对鸡蛋过敏原结构和致敏性的影响仍然是值得深入探索的科学问题,对指导生产和研发低致敏性或无致敏性蛋制品具有重要作用。     

Milk allergens, their characteristics and their detection in food: A review

Cow's milk allergy (CMA) is one of the most common food allergies in childhood. This allergy is normally outgrown in the first year of life, however 15% of allergic children remain allergic. Many studies have been carried out to define and characterise the allergens involved in CMA and described two major allergens: casein (αs1-CN) and β-lactoglobulin. In addition to this, many other milk proteins are antigenic and capable of inducing immune responses. Milk from sheep or goats differs from cow's milk (CM) in terms of composition and allergenic properties. Food processing such as heating affects the stability, structure and intermolecular interactions of CM proteins, thereby changing the allergenic capacity. Chemical and proteolytic treatments of milk to obtain milk hydrolysates have been developed to reduce allergic reactions. Prevention of CMA largely relies on avoidance of all food products containing cow's milk. To achieve this, interest has focused on the development of various technologies for detecting and measuring the presence of milk allergens in food products by immunoassays or proteomic approaches. This review describes the technologies implemented for the analysis of milk allergens (allergenicity, biochemistry) as well as their potential detection in food matrices.     

1-MCP对‘粉红女士’苹果果实采后生理及其品质的影响

为探讨1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对‘粉红女士’苹果采后生理特性及其品质的影响。用1.0 μL/L的1-MCP处理‘粉红女士’苹果24 h,以不处理为对照,20℃条件下贮藏,定期测定贮藏期间的主要品质及相关生理指标。结果表明:1-MCP处理可保持苹果贮藏过程中的硬度、可滴定酸含量,延缓果皮油腻化的发生,显著抑制果实的呼吸强度和乙烯释放速率,推迟果实过氧化氢酶、过氧化物酶两种酶活性峰值的出现,并在一定程度上提高了超氧化物歧化酶和过氧化氢酶的活性,有效抑制丙二醛含量的积累。因此,1-MCP处理可较好地调控‘粉红女士’苹果的相关生理代谢,改善果实的贮藏品质,从而有效延缓果实采后的成熟衰老进程。     

Examining the effect of High Pressure Processing on the allergenic potential of the major allergen in peach (Pru p 3)

The aim of this work is to study the effect of High Pressure Processing (HPP) on the allergenicity of the main protein involved in peach allergy (Pru p 3). Results obtained showed that most pressure/time combinations slightly enhanced in vitro IgE-binding to Pru p 3 and peach extract. Moreover, additional tests were carried out by means of skin prick tests on peach allergic patients. Different from in vitro results, in vivo effects evidenced that HPP (600 MPa/5 min) can either reduce or increase Pru p 3 allergenicity, depending on the particular sensitisation of each patient. Notwithstanding this variability, it is highly remarkable that the skin response to pressurized peach extract was stronger in more than half of individuals. These results would suggest a higher risk of HPP-treated peach products to elicit an allergenic reaction. However, it has been also proved that matrix plays an important role in peach allergenicity modification. Consequently, further investigations are needed before extrapolating results to more complex products.Industrial relevancePeach allergy is one of the most frequent allergies in Mediterranean countries among adult patients. However, up to date, there is no information about the effect of HPP on peach allergenicity. This study increases understanding about the impact of processing on an important fruit allergen in order to advance knowledge-based ways to managing allergens risks in industry, as well as it opens new opportunities of research in other technologies or strategies in the attempt to reduce peach allergenicity.