When it comes to eating and drinking, multiple factors from diverse sensory modalities have been shown to influence multisensory flavour perception and liking. These factors have heretofore been strictly divided into either those that are intrinsic to the food itself (e.g., food colour, aroma, texture), or those that are extrinsic to it (e.g., related to the packaging, receptacle or external environment). Given the obvious public health need for sugar reduction, the present review aims to compare the relative influences of product-intrinsic and product-extrinsic factors on the perception of sweetness. Evidence of intrinsic and extrinsic sensory influences on sweetness are reviewed. Thereafter, we take a cognitive neuroscience perspective and evaluate how differences may occur in the way that food-intrinsic and extrinsic information become integrated with sweetness perception. Based on recent neuroscientific evidence, we propose a new framework of multisensory flavour integration focusing not on the food-intrinsic/extrinsic divide, but rather on whether the sensory information is perceived to originate from within or outside the body. This framework leads to a discussion on the combinability of intrinsic and extrinsic influences, where we refer to some existing examples and address potential theoretical limitations. To conclude, we provide recommendations to those in the food industry and propose directions for future research relating to the need for long-term studies and understanding of individual differences.

Tastes interact in almost every consumed food or beverage, yet many aspects of interactions, such as sweet-sour interactions, are not well understood. This study investigated the interaction between sweetness from sucrose and sourness from citric and tartaric acid, respectively. A cross-cultural consumer study was conducted in China (n = 120) and Denmark (n = 139), respectively. Participants evaluated six aqueous samples with no addition (control), sucrose, citric acid, tartaric acid, or a mixture of sucrose and citric acid or sucrose and tartaric acid. No significant difference was found between citric acid and tartaric acid in the suppression of sweetness intensity ratings of sucrose. Further, sucrose suppressed sourness intensity ratings of citric acid and tartaric acid similarly. Culture did not impact the suppression of sweetness intensity ratings of citric or tartaric acid, whereas it did influence sourness intensity ratings. While the Danish consumers showed similar suppression of sourness by both acids, the Chinese consumers were more susceptible towards the sourness suppression caused by sucrose in the tartaric acid-sucrose mixture compared to the citric acid-sucrose mixture. Agglomerative hierarchical cluster analysis revealed clusters of consumers with significant differences in sweetness intensity ratings and sourness intensity ratings. These results indicate that individual differences in taste perception might affect perception of sweet-sour taste interactions, at least in aqueous solutions.

This study investigated sweet–sour taste interactions in novel sweeteners using a 3 × 2 factorial design consisting of Sweetening System (three levels: sucrose; d‐allulose; and a blend of d‐allulose and Monk fruit extract) and Acidity (two levels: with or without citric acid). 110 untrained Chinese subjects participated using the temporal check‐all‐that‐apply (TCATA) method. Mixed‐model ANOVA was conducted to investigate the effect of Sweetening System, Acidity, and their interactions on the fractional Area Under the Curve within three 20 s time intervals (attack, evolution, finish). Treatments were compared using Dunnett's test with sucrose as control. Citric acid suppressed the sweet taste of both sucrose and d‐allulose more than the blend of d‐allulose and Monk fruit extract throughout attack and evolution time intervals. This finding was confirmed by a significant interaction between Sweetening System and Acidity for sweet taste. Sour taste was not affected differently by different Sweetening Systems or the difference in sweetener concentration.Practical Applications: This study showed that the sweet taste of a blend of sweeteners could be altered by citric acid to have a similar temporal profile as sucrose in most of the evaluation time. This emphasizes the importance of not only conducting evaluations of novel sweeteners in aqueous solutions but also considering studies in more complex matrices and the choice of the methodology used to measure the sensory profile.

The underlying mechanisms of taste interactions in humans are not well understood, and three mechanisms have been proposed, namely a chemical interaction, a peripheral physiological, and a central mechanism. In the present study, it was investigated which of these mechanisms causes the suppression of sweetness by citric acid. This was investigated using a split-tongue gustometer that can stimulate the two sides of the tongue with different stimuli simultaneously, enabling a comparison of sucrose and citric acid presented either separately on each side of the tongue simultaneously or in a mixture on one side. Two studies were conducted using low (Study 1; n = 50) and high (Study 2: n = 59) concentrations of sucrose (2.5% (w/w) and 10% (w/w), respectively), and citric acid (0.14% (w/w) and 0.18% (w/w), respectively). In neither of the studies was there a significant difference in sweetness intensity ratings between the two conditions where sucrose and citric acid were presented either separately or in a mixture form. However, both showed significantly lower sweetness ratings than without citric acid indicating suppression of the sweetness of sucrose from citric acid. This provides strong evidence for a central mechanism for the suppression of the sweetness of sucrose by citric acid. This mechanism seems to be equal in high and low concentrations of both sucrose and citric acid.

Most beverages are complex matrices. Different taste compounds within these matrices interact, and thus affect the perception of the tastes. Sweetness and sourness have generally been known to suppress each other, but often such investigations have focused on aqueous solutions. Investigations into what happens when these known interactions are transferred to more complex solutions are scarce. In this study, we investigated the differences in taste interactions between an aqueous matrix and a cold-brewed coffee matrix. Two sub-studies were conducted. In one, six aqueous samples were evaluated by 152 naïve consumers; in the other six cold-brewed coffee samples were evaluated by 115 naïve consumers. In both studies participants tasted samples with no addition or with addition of either sucrose, citric acid, tartaric acid, or a mix of sucrose and either of the acids. Results showed that the sweetness of sucrose was suppressed by both citric acid and tartaric acid in both matrices. The sourness of both citric acid and tartaric acid was suppressed in the aqueous matrix, but only the sourness of tartaric was suppressed in the coffee matrix. Generally, the suppression was lower in the coffee matrix compared to the aqueous matrix. In conclusion, results from taste interaction studies conducted on aqueous matrices can to some extent, with caution, be interpolated to more complex matrices. Importantly, suppression effects might diminish with an increase in matrix complexity.

The transition to plant-based diets is advocated as a consumption measure to mitigate the environmental impacts of animal-based food production. Understanding the drivers and barriers to consumption can guide the formulation of tailored strategies for advancing plant-based alternatives in markets. This study investigated the principal drivers and barriers influencing the adoption of plant-based cheese alternatives among Danish consumers (n = 550) through an online survey. Participants were clustered based on the sensory (flavor and texture) cues using Agglomerative Hierarchical Clustering, resulting in four consumer groups: (C1) consumers who prefer plant-based cheese alternatives to closely mimic both the flavor and texture of dairy cheese (n = 172); (C2) Consumers who prefer dairy-like flavor but are open to plant-based textures (n = 141); (C3) Consumers who prefer dairy-like texture but are open to novel flavor (n = 146); and (C4) Consumers who seek variety and novelty in both flavor and texture (n = 91). The results showed that consumer preferences for flavor and texture cues are important factors in shaping their motivations and barriers toward plant-based cheese. Specifically, product availability emerged as a significant barrier for those preferring dairy-like alternatives, while sensory perception and convenience were less influential for consumers who favor novelty. Notably, the consumer clusters did not show significant statistical differences in dietary pattern types, such as omnivores, flexitarians, vegetarians, or vegans. Understanding these dynamics is essential for developing effective strategies to promote plant-based cheese alternatives and cater to varying consumer needs.