Does interindividual variability of saliva affect the release and metabolization of aroma compounds ex vivo? The particular case of elderly suffering or not from hyposalivation

Abstract

The aim of this work was to study the effects of interindividual variability of human elderly saliva on aroma release and metabolization by ex vivo approaches. Thirty individuals suffering or not from hyposalivation were selected from a panel formed by 110 elderly people (aged >65 years old) that were matched by age and sex. Then, their stimulated saliva samples were independently incubated in presence of three aroma compounds (ethyl hexanoate, octanal, 2‐nonanone) to perform headspace‐gas chromatography and liquid/liquid extraction‐gas chromatography mass spectrometry analyses. These assays revealed that the extent of saliva effect on the release and metabolization of aroma compounds was highly dependent on the chemical family of the compounds (octanal>ethyl hexanoate>2‐nonanone). Moreover, salivas from the hyposalivator (HPS) group exerted a significant lower release and/or higher metabolization than those of the control group for the three assayed compounds. Regarding the biochemical characterization of the saliva samples, no significant differences were found in the total protein content between the two groups. This does not preclude the involvement of specific proteins on the observed results that need to be clarified in further experiments. Saliva from the HPS group presented a significantly higher total antioxidant capacity than that of the control group, which suggests that this parameter could be related to the metabolization of aroma compounds by saliva. Such effects might alter aroma perception in individuals suffering from hyposalivation. Practical applications The world population is getting older so fast that most countries are not prepared to handle this demographic challenge, characterized by an increasing prevalence of noncommunicable chronic diseases (e.g., diabetes, gastrointestinal disorders) associated to inadequate eating patterns. Thus, supporting a balanced diet is one of the most cost‐effective strategies to maintain a good quality of life. A suitable diet needs to take into account both, specific sensory and nutritional individual needs. However, aging is often accompanied by deterioration in oral health (e.g., low salivary secretions), which could alter the capacities to taste and smell. Results from this work contribute to a better understanding of the role of human saliva in aroma release and metabolization, a first step to comprehend retronasal aroma release and perception. This knowledge will help to propose innovative solutions for the reformulation of food products better adapted to the elderly's needs, thus allowing delayed onset of dependency.

Understanding human salivary esterase activity and its variation under wine consumption conditions

“…36,37 In a recent work 26 using static headspace analysis, authors showed a decrease in the release of esters when they were incubated with human saliva (120 min 37 C), which did not occur in the case of inactive saliva (without enzymatic capacity). These results are in agreement with previous works, 17,28,38,39 conrming the capacity of esterase activity from human saliva to hydrolyse odorant carboxylic esters. Furthermore, in the above mentioned work, 26 the corresponding products of ester hydrolysis (carboxylic acids) were also found in the systems with human saliva, which have been associated with very different odour nuances and threshold values.…”

“…17,18 The composition of saliva varies among individuals and depends not only on genetics, but also on diet, age, gender, oral hygiene, functional status, pathologies, etc. [18][19][20] Saliva plays a signicant role in wine aroma perception, which cannot be explained by a single effect. Numerous studies have demonstrated different mechanisms of saliva inuencing volatile compounds such as, dilution, retention by salivary proteins, salting-out effects or enzymatic conversion.…”

“…[21][22][23][24][25][26][27] In this way, the capacity of salivary enzymes to metabolize certain groups of aroma compounds such as thiols, ketones, aldehydes and esters have been previously reported. 17,20,21,26,28 In the specic case of esters, synthesis or hydrolysis processes catalysed by enzymes could be particularly likely, since it is well known that human saliva presents esterase activity. 26,[29][30][31] There are different human saliva enzymes that might contribute to the total salivary esterase activity (TSEA) such as carboxylesterase, 29 carbonic anhydrase isozyme IV, 32,33 cholesterol esterase, 34 choline esterase, 31,35 lipase, 35 or even albumin.…”

Interactions among Odorants, Phenolic Compounds, and Oral Components and Their Effects on Wine Aroma Volatility

“…The scarce studies trying to elucidate the nature of these interactions have been focused on the impact of saliva on wine aroma release by using different methodological approaches (static vs. dynamic headspace), wine matrix compositions (synthetic vs. real wines), tested odorants (mixtures of aroma compounds vs. original wine volatile profile), and salivary composition/treatment (e.g., saliva centrifuged/not centrifuged) [17][18][19]. This makes it difficult to extract conclusions on the nature and significance of aroma-saliva-wine matrix interactions Additionally, recent research using aromatized solutions showed that besides the well-known dilution or salting out effects [20], saliva can act on aroma compounds at very different levels, binding different types of odorants (hydrogen, hydrophobic interactions) [21,22] and/or metabolizing them [23][24][25][26][27][28], which also might give rise to new odorant metabolites [25,27,28]. Whether these effects can be relevant in wine, and if wine matrix components might also modulate the effect exerted by saliva on aroma compounds, are some questions that need to be addressed.…”

Saliva and Food Oral Processing

“…The characteristics of saliva are greatly influenced by age (Xu, Laguna, & Sarkar, ). Age‐related salivary disorders such as hyposalivation can alter the way saliva interacts with foods and perception (Muñoz‐González, Brulé, Feron, & Canon, ). Biomarkers present in saliva can be used to differentiate individuals (Lucas, Barbosa, Castelo, & Gavião, ).…”