Sesame allergy in adults: Investigation and outcomes of oral food challenges

Recent advance in sesame allergens: Influence of food processing and their detection methods

Sesame (Sesamum indicum L.) is a valuable oilseed crop with numerous nutritional benefits containing a diverse range of bioactive compounds. However, sesame is also considered an allergenic food that triggers various mild to severe adverse reactions (e.g., anaphylaxis). Strict dietary avoidance of sesame components is the best option to protect the sensitized consumers. Sesame or sesame-derived foods are always consumed after certain food processing operations, which would cause a considerable impact on the structure of sesame proteins, changing their sensitization capacity and detectability. In the review, the molecular structure properties, and immunological characteristics of the sesame allergens were described. Meanwhile, the influence of food processing techniques on sesame proteins and the relevant detection techniques used for the sesame allergens quantification are also emphasized critically. Hopefully, this review could provide valuable insight into the development and management for the new "Big Eight" sesame allergen in food industry.

Fluorescence immunoassay based on magnetic separation and ZnCdSe/ZnS quantum dots as a signal marker for intelligent detection of sesame allergen in foods

To detect sesame allergens, a novel fluorescent immunoassay incorporating a magnetic separation step has been developed via two measurement devices: a fluorescence spectrophotometer and a smartphone equipped with a color reader. Sesame allergen monoclonal antibody (Ab) was covalently bonded with quantum dots (QDs) to act as a signal probe. The capture probes were synthesized as sesame allergen (SA) modified carboxyl-functional magnetic polystyrene microspheres (MPMs). Analytical variables such as the amount of modified SA, the reaction volume of the QDs-Ab, the ionic strength, the pH, and the incubation time of the reaction were optimized. The analytical range and the limit of detection (LOD) of the spectrophotometer-based assay were 80-640 μg/L and 12.75 μg/L, respectively. The analytical range and the LOD with smartphone read-out were 80-640 μg/L and 10.15 μg/L, respectively. Furthermore, the developed assay using the fluorescence spectrophotometer and the smartphone read-out was successfully applied to field testing of SA in solution extracts of biscuits, bread, almond beverage, and energy bars with acceptable results. The recovery rates were in the range 89-108%. It was concluded that the new assay may be used for rapid sesame allergen testing in the laboratory and in the field.

Assessment of the effect of glycation on the allergenicity of sesame proteins

Sesame allergy is a growing concern worldwide. In this study, sesame proteins was glycated with glucose, galactose, lactose and sucrose respectively, and the allergenicity of different glycated sesame proteins were assessed by a comprehensive strategy, including simulated gastrointestinal digestion in vitro, a BALB/c mice model, a rat basophilic leukemia (RBL)-2H3 cell degranulation model and a serological experiment. Firstly, simulated gastrointestinal digestion in vitro showed that glycated sesame proteins were more easily to digest than raw sesame. Subsequently, the allergenicity of sesame proteins was assessed in vivo by detecting the allergic indexes of mice, and results showed that the levels of total immunoglobulin E (IgE) and histamine were reduced in glycated sesame proteins treated mice. Meanwhile, the Th2 cytokines (IL-4, IL-5, and IL-13) were downregulated significantly, demonstrating that sesame allergy was relieved in glycated sesame treated mice. Thirdly, the RBL-2H3 cell degranulation model results showed that the release of β-hexosaminidase and histamine were decreased to different degrees in glycated sesame proteins treated groups. Notably, the monosaccharide glycated sesame proteins exhibited lower allergenicity both in vivo and in vitro. Furthermore, the study also analyzed the structure alteration of sesame proteins, and the results showed that the secondary structure of glycated sesame proteins were changed (the content of α-helix and β-sheet were reduced), and the tertiary structure of sesame proteins after glycation modification was also changed (microenvironment around aromatic amino acids was altered). Besides, the surface hydrophobicity of glycated sesame proteins was also reduced except sucrose glycated sesame proteins. In conclusion, this study demonstrated that glycation reduced the allergenicity of sesame proteins effectively, especially glycation with monosaccharides, and the allergenicity reduction might be related to structural changes. The results will provide a new reference for developing hypoallergenic sesame products.

Sesame allergy: mechanisms, prevalence, allergens, residue detection, effects of processing and cross-reactivity

Sesame allergy is a serious public health problem and is mainly induced by IgE-mediated reactions, whose prevalence is distributed all over the world. Sesame has been included on the priority allergic food list in many countries. This review summarizes the mechanism and prevalence of sesame allergy. The characteristics, structures and epitopes of sesame allergens (Ses i 1 to Ses i 7) are included. Moreover, the detection methods for sesame allergens are evaluated, including nucleic-acid, immunoassays, mass spectrometry, and biosensors. Various processing techniques for reducing sesame allergenicity are discussed. Additionally, the potential cross-reactivity of sesame with other plant foods is assessed. It is found that the allergenicity of sesame is related to the structures and epitopes of sesame allergens. Immunoassays and mass spectrometry are the major analytical tools for detecting and quantifying sesame allergens in food. Limited technologies have been successfully used to reduce the antigenicity of sesame, involving microwave heating, high hydrostatic pressure, salt and pH treatment. More technologies for reducing the allergenicity of sesame should be widely investigated in future studies. The reduction of allergenicity in processed sesames should be ultimately confirmed by clinical studies. What's more, sesame may exhibit cross-reactivity with peanut and tree nuts.

Maillard Reaction Induced Changes in Allergenicity of Food

Food allergy is increasing in prevalence, posing aheavier social and financial burden. At present, there is still no widely accepted treatment for it. Methods to reduce or eliminate the allergenicity of trigger foods are urgently needed. Technological processing contributes to producing some hypoallergenic foods. Among the processing methods, the Maillard reaction (MR) is popular because neither special chemical materials nor sophisticated equipment is needed. MR may affect the allergenicity of proteins by disrupting the conformational epitope, disclosing the hidden epitope, masking the linear epitope, and/or forming a new epitope. Changes in the allergenicity of foods after processing are affected by various factors, such as the characteristics of the allergen, the processing parameters, and the processing matrix, and they are therefore variable and difficult to predict. This paper reviews the effects of MR on the allergenicity of each allergen group from common allergenic foods.

Sesame as an allergen in Lebanese food products: Occurrence, consumption and quantitative risk assessment

Despite the intensive use of sesame in the Middle Eastern diet, studies on this allergen in this region are lacking. A survey on the occurrence of sesame in Lebanese food products that did not contain this allergen as an ingredient, a food consumption survey conducted in Beirut schools, and the most recent sesame eliciting dose estimates were used to build a probabilistic risk assessment model providing estimates of sesame-induced allergic reactions per eating occasion and per week in Lebanese children and adolescents. Of 1270 food samples analysed, 34% contained sesame proteins (0.44-3392 mg kg^-1). Sesame was detected in 47% of unlabeled bulk samples, 43% of samples with PAL, and 27% of samples without PAL. "Sfouf" had the highest concentration of sesame proteins (mean 549 mg kg^-1), highest mean exposure per eating occasion (78 mg sesame proteins for children and 103 mg sesame proteins for adolescents), and posed the highest predicted risk per eating occasion (>20%) and per week (>13% individuals predicted in simulation experience at least 1 reaction). Bakery products (notably "sfouf") may pose a serious risk to sesame-allergic children and adolescents in Lebanon. Enhanced guidance on the use of PAL is needed to better protect allergic consumers.

Food allergen labelling: "May contain" evidence from Malaysia

Food allergen labelling is mandatory and regulated whilst precautionary allergen labelling (PAL) remains voluntary in most countries. It is the aim of this study to identify the food allergens declared in food products sold in a developing country and to what extent food allergens and PAL are emphasised in the products. A total of 505 food and beverages (snacks, baked goods, confectionary, baby food, condiments & jams, beverages, powder & paste, instant food, chilled & frozen food and canned food) were evaluated in Malaysia. Soybean represents the largest group of food allergen declared in labels, followed by wheat and milk products. Thirteen variations of contains statement were found with "Contains [allergen(s)]" being the most common (55.02%). There were 22 different types of "may contain" statements with 'May contain traces of [allergen(s)]' being the most common advice labelling used (55.41%). Different font type or emphasis such as brackets (51.57%) and bold font (33.86%) were used to inform consumers about presence of allergens. The national regulations on food allergen labelling are then critically contrasted with other Asian countries and the EU Regulation No. 1169/2011, which represents one of the most stringent food regulations in the world. Improving current allergen labelling limitations and practices would be of great benefit to consumers to prevent risk of food hypersensitivity.