Heterogeneous distribution of salt and aroma in hot snacks: flavour perception, saltiness enhancement and liking

Le document qui a justifié la délivrance du diplôme est en cours de traitement par la bibliothèque de l'établissement de soutenance. Rapport confidentiel pendant 5 ans.Due to the negative effect of salt overconsumption on health, worldwide health authorities have requested food companies to reduce the salt content of their products. However, to reduce the salt content is problematic, as it induces many changes such as modification of texture, reduction of shelflife, and the decrease of palatability of food products. The first part of this work was devoted to investigate different strategies of salt reduction in hot served complex food products. Heterogeneity of salt distribution was investigated in savoury pies composed of a pastry and a cream filling layer, and in four-layer cream-based products. Then, the odour-induced saltiness enhancement strategy (OISE) and the heterogeneous distribution of flavour compounds were combined and assessed in four-layer cream-based snacks, and in savoury flans varying in the size of the ham pieces. Saltiness and acceptability were explored in these complex hot-served food products. The second part of this work was devoted to investigate the relationship between saltiness enhancement, temporal release and perception of flavour compounds in hot snacks with heterogeneous distribution of salt and aromas. Complementary technics were used: nose-space PTR-Tof-MS to assess aroma in vivo release, and Tl and TDS to investigate the perception as a function of time. Heterogeneity of salt distribution enhanced the salty perception in hot-served layered snack products, whereas a decrease in harm particle size led to an increased salty taste intensity in hot savoury flans. The strategy of concentrating salt in the outer layer of a multilayer product was found to be the optimal solution as far as taste intensity is concerned. The salty taste enhancement could be due to the initial strong dominance of the salty sensation at the very beginning of the eating process. This likely contributes to explaining why an initial aroma sensation was observed for products with homogeneous salt distribution.La surconsommation de sel peut avoir des effets négatifs sur la santé, aussi les autorités mondiales de la santé demandent aux industriels agro-alimentaires de réduire la teneur en sel dans les produits alimentaires. Cependant, le sel joue un rôle majeur dans la texture, la durée de vie et la palatabilité des aliments ce qui rend problématique sa réduction. La première partie de ce travail a été dédiée à L’étude de différentes stratégies de réduction du sel dans des modèles alimentaires complexes et servis chauds. L’hétérogénéité de répartition du sel a été étudiée dans des tartes salées composées d'une pâte et d'un appareil de type flan, ainsi que dans des flans à 4 couches. Ensuite, la stratégie de répartition hétérogene des composes de la flaveur a été combinée à celle de I'odeur induisant une augmentation de la perception salée (OISE) dans des modèles de flans à 4 couches, ainsi que dans des flans sales contenant des morceaux de jambon de tailles variables. La perception salée et I'acceptabilité ont été évaluées pour chaque des modèles alimentaires développés. La deuxième partie de ce travail a été dédiée à I'étude des liens entre augmentation de la perception salée, libération temporelle des arômes et perception temporelle de la flaveur dans des flans multicouches a répartition hétérogène en sel et en arômes. Des techniques complémentaires ont été utilisées: nose-space PTRTof-MS afin de quantifier la libération in vivo des arômes, et les méthodes de Tl et DTS afin de mesurer 1'evolution de la perception au cours du temps. Une distribution hétérogène en sel augmente la perception salée dans les snacks multicouches, tandis que la diminution de la taille des morceaux de jambon augmente la perception salée dans les aliments composites. La stratégie de concentration du sel dans la couche extérieure des aliments multicouches est la solution optimale en termes de perception salée. L'augmentation de la perception salée pourrait être due a une forte dominance initiale de la perception salée, qui apparaitrait au tout début de la consommation des produits. Ceci expliquerait aussi pourquoi la sensation d’arôme est dominante lors de la consommation de produits à répartition homogène en sel

Ham particle size influences saltiness perception in flans

One major issue of the food industry is reducing sodium content while maintaining food acceptability and liking. Despite extensive research in this field, little has been published on real complex food products. The aim of this study was to investigate whether the size of particles, a parameter easily adjusted in food processing, could influence the salty taste of low-salt food product. We thus evaluated the effect of ham particle sizes (4 levels, including a zero level) on salt perception and the consumer liking of flans varying in their overall salt concentrations (low- and high-salt content). Two consumer panels, composed of 107 and 77 subjects, rated, respectively, the saltiness of and liking for the developed flans (8 samples). The outcomes of this study indicated first, that the addition of ham to flans increased the salty taste perception and second, that a decrease in ham particle size (ground ham) increased the perceived saltiness. Moreover, low- and high-salt flans were equally liked, demonstrating that food manufacturers could reduce the salt contents (here, by over 15%) while maintaining consumer acceptability through the manipulation of the size of the salt-providing particles. Practical Application The results from this study can contribute to low-salt food design with a good acceptability by the consumers. Because salted ham particles are heterogeneously distributed in flans, the salty perception is increased compared to a homogeneous distribution of salt in flans. Moreover, a decrease in ham particle size increases the overall surface of particles, which efficiently increases the perceived saltiness. Salt content and particle size of some ingredients can be optimized to enhance saltiness of low-salt composite foods, without addition of any additive and without significant loss of sensory acceptability

La répartition hétérogène du NaCl influence la perception salée

Le régime alimentaire occidental conduit à une surconsommation de sodium deux fois supérieure au niveau recommandé. Le sodium est majoritairement apporté par le sel (NaCl) et sa consommation en excès est un des facteurs responsable de l’augmentation de l’hypertension artérielle. Ainsi, les pouvoirs publics recommandent-ils une réduction de 20% de la teneur en sel dans les principaux vecteurs alimentaires, tel que les plats préparés et les snacks. Cependant, il est difficile de réduire le taux de sel dans ces aliments tout en maintenant leur qualité gustative. En effet le sel confère aux aliments une saveur salée gage de leur palatabilité. Ce travail s’inscrit dans une recherche globale sur les moyens de réduire le taux de sel dans les aliments tout en maintenant leur appréciation. Il a pour objectif d’étudier l’influence de la distribution du sel dans la matrice alimentaire sur la perception salée. Cette étude est particulièrement originale dans la mesure où elle est basée sur un modèle alimentaire complexe comprenant deux phases, l’une riche (R) et l’autre pauvre (P) en eau. L’influence de la répartition du sel dans ces deux phases R et P a été étudiée selon un plan complet reposant sur 3 concentrations en sel. L’intensité de la perception salée a été déterminée par un panel de consommateurs naïfs (n= 87) pour les 9 produits alimentaires du plan expérimental. Les résultats montrent que la perception salée est différente selon que la concentration en sel varie dans la phase R ou dans la phase P (F=482.81, p<0.0001 et F=3.30, p< 0.05, respectivement). Cependant, une réduction du taux de sel dans la phase P lorsque la phase R contient du sel, ne modifie pas significativement l’intensité salée perçue dans le produit. Ces résultats démontrent qu’une répartition hétérogène du sel dans un aliment réel peut permettre une réduction significative de la concentration en sodium globale du produit, tout en maintenant l’intensité de la perception du goût salé

Heterogeneous salt distribution: A way to enhance saltiness without loss of acceptability

Health authorities recommend a drastic reduction of salt content in food products. However, such reduction leads to a decrease in both saltiness and acceptability. In a series of experiments, we investigated a new strategy to compensate for salt reduction in food. We assessed the effect of heterogeneous salt distribution on saltiness enhancement, and food acceptability. First, we examined whether salt distribution could affect sodium perception in a salty baked food. This model food is composed of two layers: a cream-based and a cereal-based layer. Three salt levels were tested within each layer, according to a full factorial design. A panel of consumers (n=87) evaluated saltiness of each food product. The results showed that salt perception depended on salt concentration as a function of layer composition: salt concentration induced much more difference in saltiness for the cream-based layer (p<0.0001) as compared to the pastry layer (p=0.01). As a consequence, reducing total salt concentration up to 40% had almost no effect on saltiness. Second, we investigated whether a heterogeneous distribution of salt in the creambased layer could affect sodium perception and product acceptability. We designed a multilayer cream-based model food, and varied salt concentration in each layer thus inducing a low, medium, or large contrast of salt concentration between layers, while maintaining the total salt level. Two consumer panels (n= 102 and n=80) rated respectively saltiness and liking. The results highlighted that the product with the largest contrast in salt concentration was perceived as the saltiest (p<0.0001). Furthermore, acceptability for this product was not different from a control product containing 20% more salt but homogeneously distributed. These findings demonstrated that heterogeneous salt distribution is a powerful strategy to compensate for salt reduction in food and to design healthier products while optimising taste

Heterogeneous distribution of aroma and salt in food enhances salt perception

In the worldwide context of healthy diet, taste enhancement is essential to maintain low salt food acceptability. Aroma-taste interactions and heterogeneous distribution of tastants were used as strategies for taste enhancement. However, the combination of these two strategies has never been studied. This study investigated the effect of heterogeneous aroma-salt distribution on salty taste enhancement and consumer acceptability of hot snacks. A four-layers cream-based model food was designed with the same total amount of sodium and ham aroma, but their distribution varied in each layer. Low, medium or large contrasts between layers of salt and aroma concentration were used, according to an optimized experimental design. Control products with no added ham aroma were included, which resulted in 10 products. A consumer panel (n=82) rated for each product: salty, sweet, bitter, sour and umami taste intensity, as well as ham and cheese aroma intensity. Additionally, they evaluated their acceptability for the products during another sensory session. Results showed first that ham aroma enhanced saltiness (p<0.07) in homogeneous product compared to the control containing salt only. Secondly, products with the largest contrast in salt concentration were perceived more salty (p<0.01), regardless of the distribution of the ham aroma. Thirdly, the product with the largest contrasts in salt and aroma concentration, i.e. distributed on extreme layers, was even perceived as saltier than the product containing 20% more salt homogeneously distributed. Interestingly, consumer acceptability did not differ significantly between all products. This set of results led us to conclude that a well-designed heterogeneous distribution of salt and aroma in hot snacks could compensate for at least 20% of salt reduction, while maintaining salt perception and food acceptability

Salt distribution in food influences salt perception

Salt (NaCl) consumption is recognized as an important factor in the rise of hypertension in industrialized countries. Therefore, health authorities recommend a reduction of 20% of salt content (generally salt is present about 0.5 to 2g per 100g of food) in several food products such as ready meals and snacks. However, salt reduction in processed foods induces numerous technical difficulties since salt has a number of functions: preservation, water and fat binding and flavour enhancement. Indeed, salt gives a salty taste that guarantees food palatability. The present study is in line with global research to reduce salt level in foods while maintaining saltiness. The aim is to evaluate the influence of salt distribution on salt perception, in a complex food matrix. The model food includes two distinct layers: the lower layer is a pastry and the upper layer is made of a semi-solid custard. The influence of salt distribution within the two layers has been studied through a full factorial design including two factors: concentration of salt added in the lower layer and the upper layer (without salt, 0.3 and 1g per 100g). Saltiness intensity of the 9 products was rated by a panel of 87 naive consumers. The total salt concentration in each product was checked by HPLC (High Performance Liquid Chromatography). Results showed that salt concentration impact saltiness but differently according to the layer. Salt concentration variation induces much more difference in salt perception in the upper layer (F(2, 672)=664, p<0.0001) as compared to the lower layer (F(2, 672)=4.7, p=0.01). As a consequence reducing salt level in the upper semi-solid custard layer led to a drastic decreased in saltiness while reducing salt in the pastry layer did not. In conclusion, these results demonstrate that a heterogeneous distribution of salt in real food products could be used to maintain organoleptic characteristics of reduced salt food

Dumping effects measured in cream cakes: influence of response alternatives

Sensory panellists are often asked to make intensity judgments for a sensory attribute of a stimulus. However, it is well known that a multidimensional stimulus entails this judgment, and could lead to a carryover effect of the intensity of sensations as a function of the number of available attributes. This phenomenon has been called the “dumping” effect and could especially appear as a methodological issue in cross-modal interactions studies. The aim of this study was to investigate the influence of the number of attributes on the rating of a target attribute (saltiness) of several variants of a food-product and to assess the extent to which dumping affect judgment between variants. Nine variants of cream cake were chosen in this study. They differed by the presence of ham (no, small pieces, large pieces) and by salt concentration (2 levels), and were evaluated in three conditions. In the first condition, 102 naive panellists rated the nine variant using a single scale: saltiness. Then, 98 panellists were recruited after a selection test based on their capacity to use rating scales and to perceive 3 different concentrations of tastes and aromas in quark. One half of this panel participated, to the second condition, in which 4 attributes were available (salty, sweet, aroma intensity and ham pieces size) whereas, in the third condition, the other half used 8 attributes (salty, sweet, sour, bitter, umami, ham and emmental aroma intensity, and ham pieces size). ANOVA results revealed a significant influence of rating condition on reported saltiness (F=25.1, p<0.0001) as well as a significant difference between products for this attribute (F=17.9, p<0.0001). However, no significant interaction was observed between these two factors indicating that, even if dumping occurs in the profiling of the multidimensional stimuli, it does not affect the discrimination between products

Heterogeneous salt distribution in hot snacks enhances saltiness without loss of acceptability

clef UT: 000318667000026International audienceAbstract Health issues have led worldwide organisations to encourage the food industry to reduce salt in processed foods. Therefore, different strategies for salt reduction have been investigated. Here, the effect of heterogeneous salt distribution on saltiness perception intensity was assessed to compensate for salt reduction in snack foods. Two models of hot-served baked foods were developed. One model is made of two layers that vary in composition (cream-based and cereal-based layers) and salt (NaCl) concentration; the other one is made of four cream-based layers that vary in salt concentrations. Consumer panels rated the saltiness intensity for each product and their liking for the four-layer products only. A significant enhancement of saltiness was observed in samples with a heterogeneous salt distribution for both types of snacks. In the bi-layer products, salt perception was more dependent on the salt concentration in the cream-based layer than in the cereal-based layer. Moreover, a large contrast in the salt concentrations was required to enhance salt perception for the four-layer products. Our results show that heterogeneous salt distribution is a powerful strategy to compensate for salt reduction in foods and to design healthier products while optimising taste

In-mouth salt release measurement during food chewing using sensors

This is a RoMEO ungraded journalIn most countries, health authorities recommend a 20% reduction of the salt content in manufactured food products. Understanding the release of taste compounds from food is essential to better known the mechanism of flavour perception, in order to develop low salt products that are acceptable to the consumers. In this aim, two sensors have been designed to allow the in‐mouth monitoring of conductivity from 0.34 to 340 mM NaCl and temperature during mastication of hot snacks as conductivity is highly dependant on the temperature

Food saltiness optimization using in-mouth sensors

Food saltiness optimization using in-mouth sensors. International symposium olfaction & electronic noses (ISOEN 2011