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L17: Astringency, a new insight into salivary PRP - tannin interaction

Abstract : Astringency is one of the main organoleptic properties involved in plant-based food choice and. acceptance by the consumer. Astringency is defined as ‘the complex of sensations due to shrinking,. drawing or puckering of the epithelium as a result of exposure to substances such as alums or tannins’. (ASTM, 1989). This sensation is particularly important in plant-based food, as tannins are ubiquitous in. plants. The physicochemical bases of astringency are still obscure, but it is generally accepted that its. perception results from tannin interaction and/or aggregation with salivary proteins and glycoproteins,. causing loss in the lubricating power of saliva. Among salivary proteins, proline-rich proteins (PRPs), which represent almost 70 % of the proteins in stimulated saliva, have demonstrated a stronger affinity for. tannins than other proteins 1. Regardless of the exact mechanism of astringency, it is clear that. interactions between tannins and salivary PRPs occur in the mouth. In the same time, it is interestingly to. note that herbivores synthesize PRP while carnivores do not. Moreover, tannins are involved in plant. defense mechanisms as they are able to inhibit gastrointestinal enzymes and therefore to reduce the. digestibility of plant foods. As the only function described for basic PRP (bPRP) is to bind and scavenge. tannins 2,3, the secretion of PRPs appears to be a defense mechanism developed by mammals against. dietary exposure to tannins, in order to protect other proteins like enzymes. Herein, we investigate the interaction of a human bPRP, IB5, with a model tannin, epigallocatechin. gallate, using mass spectrometry (MS), dynamic light scattering (DLS) and small angle X-ray scattering. (SAXS). In the present work, we address the following questions:. - How strongly do EgCG molecules bind to IB5, how many binding sites are there on each protein,. what are the sites of interaction, and what is the distribution of EgCG on these sites? - How many tannins are needed to cause aggregation of the proteins, what is the average number of. proteins per aggregate, and what is the structure of these aggregates ?. - Are these aggregation and precipitation processes relevant for phenomena that take place in the. mouth? The results obtained by the three techniques have allowed us to answer the above questions. The. information collected gives a new insight into the comprehension of PRP – tannins interactions, which. probably impact astringency perception. Astringency, proline-rich proteins, tannins, noncovalent interaction, intrinsically disordered proteins.
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  • HAL Id : hal-02805029, version 1
  • PRODINRA : 272848

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Francis Canon. L17: Astringency, a new insight into salivary PRP - tannin interaction. 2. International Conference on Food Oral Processing - Physics, Physiology and Psychology of Eating, Jul 2012, Beaune, France. 1 p. ⟨hal-02805029⟩

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