Fermented foods (FF) are produced by the transformation of the raw material by microorganisms, giving organoleptic and/or conservation properties to the food. Consequently, they are sources of living microorganisms and there is a body of clue that their regular consumption, in particular the ones containing Lactic Acid Bacteria (LAB), is a promoting factor of human health. Moreover, considering the regularity of the consumption, LAB could modulate the oral microbiota (OM) and the oral functions of the host. The composition of the OM has been shown to be related to taste sensitivity (TS) in human. Therefore, a modulation of the OM could modify TS. Despite a certain disparity between studies, some LAB can persist in the oral cavity from several hours to several days with an important inter-individual variability. The factors at the origin of this variability are not fully known but they could include the oral environment properties such as the oral biology and the interactions with the host OM. Our group has recently shown that oral LAB persistence was lower in rats presenting markers of response to oxidative stress in their saliva. This last finding leads to the hypothesis that a pro-oxidative diet could be an antagonistic factor to the persistence of LAB in the oral cavity. The vegetarian diet has been reported to be less oxidative than the omnivorous diet in many studies. Therefore, subjects who adopted a vegetarian diet appear to be appropriate candidates to study LAB oral persistence and activity. The overall objective of the present project is to elucidate the contribution of oral factors and FF consumption habits on oral LAB persistence and activity and on TS in vegetarian versus omnivorous subjects. The PERSIST project involves 3 research units with expertise in sensory sciences, salivary biochemistry, microbiology and metagenomics.

Although chemical signals are crucial for a diversity of biological functions and have been extensively studied in terrestrial mammals, olfactory and gustatory abilities have been poorly investigated in cetaceans. Our project aims to give an exhaustive insight into the chemical communication and to investigate the evolutionary adaptations of these sensory systems in a unique assemblage of mammals that re-entered the marine realm and exhibit a fully aquatic existence. Our approach is both original and multidisciplinary. It involves specialists with complementary backgrounds to integrate 3 levels of exploration: BEHAVIOURAL LEVEL to investigate the involvement and adaptive function of chemical communication in the feeding behaviour and the social life. NEURO-ANATOMICAL LEVEL to explore the nervous structures involved in the perception and the processing of chemical cues and CHEMICAL LEVEL to identify the molecules emitted by individuals and potentially involved in communication.

According to the nutritional and health recommendations of the French National Program for Nutrition and Health (Programme National Nutrition Santé, PNNS), the development of food products combining nutritional and organoleptic qualities for the benefit of the consumers' health and well-being is of paramount importance. The reduction of salt, sugar and fat represents one of the means for the development of food with good nutritional quality. This reduction can however be associated with a loss of organoleptic quality of reformulated food. Meanwhile, hedonic properties of food represent a key factor for its palatability. Since consumers’ preferences lean towards a high liking for sweet and fat food, new means to avoid rejection of healthier food are required. Food can be regarded as a complex multimodal perceptual stimuli, involving several dimensions. The holistic perception of taste, odor and aroma constitutes the flavor, which gives its identity and typicality to a food product. It is difficult to distinguish between the taste and the aroma: what is often believed to be the "taste" of food is in reality its odor. Interestingly, due to the association of aroma and taste into a single object named flavor, when a taste–odor association exists, the odor alone may be sufficient to produce the flavor perception. For example, the taste of a sucrose solution is perceived sweeter after addition of a caramel aroma. Likewise, an odor associated to a salty taste can enhance the salty perception. In this way, flavorings can be used to counterbalance salt, sugar or fat reduction in foods. Aromas are often perceived in mixtures, which can lead to a homogeneous percept when a single odor is perceived from the mixture. The homogeneous percept is the subject of important applications in food flavoring, either to give or restore flavor typicality through the use of blending aroma mixtures, or to mask off-flavors. Nevertheless, the processes involved in the homogeneous perception of odor mixtures are still poorly understood. In this context, a fundamental study of homogeneous percept can bring essential knowledge to manage the aroma formulation, which, in turn, will result in food that meets both consumer expectations and criteria of healthy food. The objective of the MULTIMIX project is to identify the biological and molecular characteristics of odorants that induce a homogeneous percept. In this perspective, MULTIMIX proposes a strong combination of in silico, in vitro, ex-vivo and in vivo approaches. Together, these approaches will be used to improve the understanding of homogeneous perception of odor mixtures and to provide, in fine, an assemblage of models for decision-support in formulation of aroma blending. Peripheral mechanisms occurring in the nose have been proposed to play a decisive role in the processing of mixture information. The understanding of mechanisms involved in the perception of odor mixtures at the peripheral level of olfactory process is a challenging subject. In the MULTIMIX project, we will capitalize on previous studies done by several partners of the MULTIMIX consortium to explore the properties of several mixtures of odorants eliciting blending and masking. For instance, we will investigate the mixture of two odorants having strawberry and caramel odors respectively, which gives rise to the configural odor of pineapple. MULTIMIX is an ambitious project that will have a significant impact in several domains of food chemistry and olfactory perception (food science, psychophysics, computational chemistry, neurophysiology, cognitive neurosciences).

FLAMME addresses a new and emerging question, the role of the oral microbiota in the flavour perception of aroma precursors. During food consumption, oral microbes are able to generate fragrant molecules in-mouth, but evidences concerning the entailed molecular mechanisms remain scarce. FLAMME aims to identify the involved microbial enzymes and characterize their activities as a function of salivary parameters related to the host physiology, by integrating results from -omics, molecular and sensory approaches. The results will help to understand the impact of the oral microbiota metabolism on flavour perception and additionally, it will pave the way for the modulation of this metabolism for an improved control of flavour generation in-mouth.