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Food processing can have many beneficial effects. However, processing may also alter the allergenic properties of food proteins. A wide variety of processing methods is available and their use depends largely on the food to be processed. In this review the impact of processing (heat and non-heat treatment) on the allergenic potential of proteins, and on the antigenic (IgG-binding) and allergenic (IgE-binding) properties of proteins has been considered. A variety of allergenic foods (peanuts, tree nuts, cows' milk, hens' eggs, soy, wheat and mustard) have been reviewed. The overall conclusion drawn is that processing does not completely abolish the allergenic potential of allergens. Currently, only fermentation and hydrolysis may have potential to reduce allergenicity to such an extent that symptoms will not be elicited, while other methods might be promising but need more data. Literature on the effect of processing on allergenic potential and the ability to induce sensitisation is scarce. This is an important issue since processing may impact on the ability of proteins to cause the acquisition of allergic sensitisation, and the subject should be a focus of future research. Also, there remains a need to develop robust and integrated methods for the risk assessment of food allergenicity. © 2015 The Authors. Chemicals/CAS: immunoglobulin E, 37341-29-0; immunoglobulin G, 97794-27-9

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Allergic diseases such as allergic rhinitis, allergic asthma, atopic eczema and food allergy have become an increasing health problem world-wide, affecting between 20-30% of the total population. Peanut allergy (prevalence ~1%) is a common and persistent food allergy accounting for severe allergic reactions. Peanuts are often consumed after thermal processing (e.g. boiling, roasting) which can alter the protein structure and change its immunoreactivity and allergenicity. In vitro diagnostic testing, however, is generally performed using the native, unprocessed protein and more knowledge on the effect of processing on allergens is necessary to improve these diagnostic procedures. In addition, rationally designed processing could also lead to reduction of the allergen content in certain products and therefore be an effective food technological approach in allergy management. Another approach in allergy management is the use of immunomodulating foods, such as probiotics. There are indications that probiotics, e.g. specific lactic acid bacteria, could be beneficial for many conditions, including different clinical expressions of allergy. Chapter 1 gives an overview of several aspects of allergy with a focus on food allergy. Firstly the basic mechanism and the involved immune cells are discussed, after which the prevalence of food allergy in the context of the EuroPrevall project is described. Different food allergens are discussed with an emphasis on the allergens from peanut and different methods are described to assess the potential allergenicity of proteins under widely used processing conditions, including heating and the Maillard reaction. Lastly, different methods to prevent or treat allergies are discussed with a special emphasis on immunomodulation by lactic acid bacteria. This introduction chapter is concluded with the research aim and thesis outline. Section 1: Influence of processing on allergenicity of proteins In our first study, described in Chapter 2, Ara

Background Peanut allergy is one of the most common and severe food allergies, and processing is known to influence the allergenicity of peanut proteins. We aimed to establish the effect of heating and glycation on the IgE-binding properties and biological activity of 2S albumins (Ara h 2/6) from peanut. Methodology/Principal Findings Native Ara h 2/6 was purified from raw peanuts and heated in solution (15 min, 110°C) in the presence or absence of glucose. Ara h 2 and 6 were also purified from roasted peanut. Using PBMC and sera from peanut-allergic patients, the cellular proliferative potency and IgE reactivity (reverse EAST inhibition) and functionality (basophil degranulation capacity) of allergens were assessed. Heating Ara h 2/6 at 110°C resulted in extensive denaturation, hydrolysis and aggregation of the protein, whilst Ara h 2 and 6 isolated from roasted peanut retained its native conformation. Allergen stimulation of PBMC induced proliferation and Th2 cytokine secretion which was unaffected by thermal processing. Conversely, IgE reactivity and functionality of Ara h 2/6 was decreased by heating. Whilst heating-glycation further reduced the IgE binding capacity of the proteins, it moderated their loss of histamine releasing capacity. Ara h 2 and 6 purified from roasted peanut demonstrated the same IgE reactivity as unheated, native Ara h 2/6. Conclusions/Significance Although no effect of processing on T-cell reactivity was observed, heat induced denaturation reduced the IgE reactivity and subsequent functionality of Ara h 2/6. Conversely, Ara h 2 and 6 purified from roasted peanut retained the structure and IgE reactivity/functionality of the native protein which may explain the allergenic potency of this protein. Through detailed molecular study and allergenicity assessment approaches, this work then gives new insights into the effect of thermal processing on structure/allergenicity of peanut proteins.