What impact does saliva have on the physical characteristics of the food bolus as it undergoes oral processing?

International audienceDeveloping novel foods tailored for specific groups requires further understanding of the intricacies involved in food oral processing, particularly the crucial role played by saliva. Saliva facilitates food oral processing, bolus formation, swallowing, and sensory perception, in addition to contributing to oral health and phonation. Ageing, health affections and polymedication are among many causes of altering salivary production, modifying the food impregnation ratio, and in turn altering the characteristics of the bolus, swallowing, and quite possibly digestion.In this in vitro work, using the AM2 masticator apparatus, we investigated the effect of salivary fluid characteristics, i.e., composition, quantity (from absence to hypersalivation), temperature, and enzymatic action, on the physical characteristics (i.e., particle size distribution (PSD), bolus mass, salivary fluid content) of in vitro boluses of Traditional French baguette.According to previous in vivo data, a ready-to-swallow bolus of French baguette displays on average a d50 value (sieve size through which 50% of the bolus weight can pass) of 4.1 ± 0.7 mm, with saliva constituting 33% of the final bolus weight. Our in vitro results, performed under normal mastication, suggest that the saliva quantity in mouth is a key factor in determining both PSD and hydration of bread boluses during oral processing. Indeed, the absence of saliva in mouth led to deficient oral processing, forming bread boluses constituted by extremely big particles (~80% particles >7.1 mm) that likely cannot be swallowed safely, while on the contrary, an excess of saliva favoured an excessive breaking down of bread, leading to boluses constituted by smaller particles than those formed under healthy salivary conditions (d50 = 3.1 mm), having a higher salivary fluid content (+10%). On the other hand, the salivary fluid temperature (37°C) did not affect PSD, d50, weight, or fluid content of bread boluses, however, the addition of human salivary α-amylase did, favouring particle size reduction (d50 decreased to 2.6 mm).Therefore, beyond the correlation between bolus hydration by saliva and food properties such as hardness and moisture content, our findings indicate that the quantity of salivary fluid present in the oral cavity and the enzymatic activity of salivary α-amylase during bread mastication significantly influence both the particle size distribution and the fluid content of bread boluses, ultimately determining the physical properties of the bolus

How does saliva affect bread oral processing?: From artificially-simulated dry mouth to hipersalivation

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TOWARDS A DIAGNOSIS OF NON-CELIAC GLUTEN SENSITIVITY: the contribution of metabolomics for monitoring metabolites produced by in vitro digestates of bread

International audienceBody fluid metabolomics is a large-scale approach allowing exploring the mechanisms that might underlie specific diseases or sensitivity to processed foods, and identifying associated biomarkers for diagnostics or stratification. Over the past decade, the non-celiac gluten sensitivity (NCGS) is more and more self-diagnosed, which makes the gluten-free diet more frequent, without objective clinical criteria. In fact, because of a lack of clinical indicators, NCGS is poorly understood and challenging to diagnose in contrast to celiac disease. Therefore, finding biomarkers associated with this phenotype is critical for an accurate diagnosis and innovative patient management.To understand the relationship between bread digestion mechanisms and the occurrence of NCGS, a recent approach with in vitro investigation was applied to study the overall digestive process of different breads, combining tools from the oral step thanks to the AM2 masticator apparatus, until the end of digestion thanks to a dynamic digester (DIDGI©) mimicking the physiology of the adult gastrointestinal tract "GIT". One objective in this study was to monitor metabolites produced by in vitro digestates using an untargeted metabolomics approach.In this study, we will outline the methodological strategy taken from preparation of the stomach and intestinal digestates, to acquisition, processing, and annotation of the LC-HRMS data.Interestingly, the first results show fluctuations in certain metabolites identified according to the type of bread digested. This reveals the impact of type of bread on the digestibility and allowed us to emphasize the contribution of metabolomic approach for monitoring the metabolites produced by in vitro digestates

The role of texture in the palatability and food oral processing

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