A Mendelian Trait for Olfactory Sensitivity Affects Odor Experience and Food Selection

SummaryHumans vary in acuity to many odors [1–4], with variation within olfactory receptor (OR) genes contributing to these differences [5–9]. How such variation also affects odor experience and food selection remains uncertain [10], given that such effects occur for taste [11–15]. Here we investigate β-ionone, which shows extreme sensitivity differences [4, 16, 17]. β-ionone is a key aroma in foods and beverages [18–21] and is added to products in order to give a pleasant floral note [22, 23]. Genome-wide and in vitro assays demonstrate rs6591536 as the causal variant for β-ionone odor sensitivity. rs6591536 encodes a N183D substitution in the second extracellular loop of OR5A1 and explains >96% of the observed phenotypic variation, resembling a monogenic Mendelian trait. Individuals carrying genotypes for β-ionone sensitivity can more easily differentiate between food and beverage stimuli with and without added β-ionone. Sensitive individuals typically describe β-ionone in foods and beverages as “fragrant” and “floral,” whereas less-sensitive individuals describe these stimuli differently. rs6591536 genotype also influences emotional associations and explains differences in food and product choices. These studies demonstrate that an OR variant that influences olfactory sensitivity can affect how people experience and respond to foods, beverages, and other products

Influence of evoked contexts on hedonic product discrimination and sensory characterizations using CATA questions

This research contributes new understanding of the role of consumption context. 12 studies involving 1727 consumers were conducted as central location tests (CLT). Using between-subjects experimental designs, the influence of evoked contexts relative to control condition for hedonic responses and sensory product characterization using check-all-that-apply (CATA) questions was evaluated. Contexts were evoked by asking consumers to think of the last time they ate/drank the focal product category or by imagining a specific consumption situation where product consumption would take place (e.g., breakfast on a weekend morning). In half of the studies, consumers were asked to provide a description of the consumption context they imagined. There was no consistent trend in the results regarding the influence of evoked context of hedonic responses. Effects were seen in a minority of studies, but not consistently showing differences in mean scores or changes in sample discrimination. The type of context that was evoked (last time ate/drank vs. specific situation) did not systematically influence the results, although the use of a description phase during context evocation was detrimental to hedonic sample discrimination. In all the studies where participants were asked to describe the context they imagined, hedonic discrimination was inferior to that achieved under no evoked context. Sensory responses to CATA questions were highly similar under evoked and no evoked context and suggested that product characterisations generated by consumers in a typical CLT provide a good proxy for sensory product experience in contextualised consumption situations.Financial support was obtained from The New Zealand Ministry for Business, Innovation & Employment and Plant & Food Research, Comisión Sectorial de Investigación Científica (Universidad de la República, Uruguay), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil), Spanish Ministry of the Economy and Competitiveness (AGL2012-36753-C01) and EU FEDER funds. Staff at The New Zealand Institute for Plant and Food Research Ltd. are thanked for help in planning and collection of data

Immunoglobulin-E-binding epitopes of wheat allergens in patients withfood allergy to wheat and in mice experimentally sensitized to wheat proteins

International audienceAt present, B cell epitopes involved in food allergy to wheat are known only for a few allergens and a few categories of patients. To characterize the epitopes of different wheat kernel allergens: α-, γ, ω2, and ω5-gliadin, a low-molecular-weight (LMW) glutenin subunit, and a lipid transfer protein (LTP1) recognized by allergic patients and by sensitized mice and provide further understanding of the role of structure in determining allergic response. Sera were obtained from 39 patients suffering from food allergy to wheat. BALB/c mice were sensitized to gliadins or LTP1 by intraperitoneal immunizations. Continuous epitopes bound by IgE were delineated by the Pepscan technique. The response to reduced, alkylated LTP1 was compared with that of the native form to evaluate the importance of protein folding on IgE reactivity. Few continuous epitopes of LTP1 reacted with IgE from allergic patients and mice, but one of them was common to several patients and sensitized mice. The unfolded protein was not recognized by either patient or mouse IgE, emphasizing the major role of LTP1 folding and discontinuous epitopes in IgE-binding. In contrast, many continuous epitopes were detected by patient and mouse IgE especially for an ω5-gliadin, which is an unstructured protein, and to a lesser extent, for the other gliadins and a LMW-glutenin subunit.The conformation of LTP1 appeared to have a strong impact on the type of IgE-binding epitopes elicited by this protein in both man and mouse. The responses in mice sensitized to gliadins or LTP1 were sufficiently comparable with the human response in terms of IgE-binding epitopes to provide support for the use of the mouse model in further investigations

Comparison of IgE-binding epitopes on wheat gliadins for patients with food allergy and experimentally sensitized mice

International audienceMice models of allergy to wheat proteins have been recently developed but have not been characterized for epitope pattern. In our laboratory, mice were sensitized with total gliadins and produced IgE antibodies that recognize the different gliadin classes :α,β,γ, *1,2 and *5. The relevance of this mouse model has to be evaluated regarding IgE-binding epitopes. The aim of the study is to compare B-cell epitopes in wheat allergic patients and sensitized mice in order to find out whether IgE antibodies elicited in mice are representative of human ones