Common bitter stimuli show differences in their temporal profiles before and after swallowing

An overview of bitter compounds in foodstuffs: Classifications, evaluation methods for sensory contribution, separation and identification techniques, and mechanism of bitter taste transduction

The bitter taste is generally considered an undesirable sensory attribute. However, bitter-tasting compounds can significantly affect the overall flavor of many foods and beverages and endow them with various beneficial effects on human health. To better understand the relationship between chemical structure and bitterness, this paper has summarized the bitter compounds in foodstuffs and classified them based on the basic skeletons. Only those bitter compounds that are confirmed by human sensory evaluation have been included in this paper. To develop food products that satisfy consumer preferences, correctly ranking the key bitter compounds in foodstuffs according to their contributions to the overall bitterness intensity is the precondition. Generally, three methods were applied to screen out the key bitter compounds in foods and beverages and evaluate their sensory contributions, including dose-over-threshold factors, taste dilution analysis, and spectrum descriptive analysis method. This paper has discussed in detail the mechanisms and applications of these three methods. Typical procedures for separating and identifying the main bitter compounds in foodstuffs have also been summarized. Additionally, the activation of human bitter taste receptors (TAS2Rs) and the mechanisms of bitter taste transduction are outlined. Ultimately, a conclusion has been drawn to highlight the current problems and propose potential directions for further research.

Dynamic characteristics of sweetness and bitterness and their correlation with chemical structures for six steviol glycosides

Time-intensity (TI) dynamic sensory characterization was used to evaluate the temporal sweet and bitter perception of six commonly available steviol glycosides (Rubusoside, Stevioside, Rebaudioside C, Rebaudioside A, Rebaudioside D and Rebaudioside M). All parameters extracted from TI curves significantly varied among the six samples for both sweetness and bitterness. Compared to other compounds, Rebaudioside M and Rebaudioside D had faster onset of sweetness, quicker decay of aftertaste, and were nearly devoid of bitterness. Conversely, Rubusoside and Stevioside demonstrated an immediate distinct bitter taste and lingering aftertaste. Based on these results, a further investigation into the relationship between temporal properties and chemical structures was conducted. It was found that fewer glucosyl groups on C-19 would result in shorter time for initial stimulation and longer perception of bitterness, whereas more glucosyl groups on C-13 could trigger a faster increase and stronger intensity of sweetness. A shorter time to the peak for sweetness was obtained when the ratio of the number of glucosyl groups on C-13 to that on C-19 was lower, although there was no such effect on bitter taste. These relationships were explained by the adsorption and desorption of these compounds on the taste receptors. Higher numbers and larger sizes of substitutions at the C-19 position of steviol glycosides can increase their desorption percentages and lead to a quicker decay of sweetness. Meanwhile, compounds with fewer glucosyl groups, such as Rubusoside and Stevioside, presented lower desorption and thus longer bitter aftertaste. Overall, the addition of glucosyl groups would generate stronger sweetness and less bitterness if the substituent number on C-13 was closer to that on C-19. These findings conveyed insights into how to modify steviol glycosides to enhance their quality as sweeteners.

Commercializing Sonic Seasoning in Multisensory Offline Experiential Events and Online Tasting Experiences

The term "sonic seasoning" refers to the deliberate pairing of sound/music with taste/flavour in order to enhance, or modify, the multisensory tasting experience. Although the recognition that people experience a multitude of crossmodal correspondences between stimuli in the auditory and chemical senses originally emerged from the psychophysics laboratory, the last decade has seen an explosion of interest in the use and application of sonic seasoning research findings, in a range of multisensory experiential events and online offerings. These marketing-led activations have included a variety of different approaches, from curating pre-composed music selections that have the appropriate sonic qualities (such as pitch or timbre), to the composition of bespoke music/soundscapes that match the specific taste/flavour of particular food or beverage products. Moreover, given that our experience of flavour often changes over time and frequently contains multiple distinct elements, there is also scope to more closely match the sonic seasoning to the temporal evolution of the various components (or notes) of the flavour experience. We review a number of case studies of the use of sonic seasoning, highlighting some of the challenges and opportunities associated with the various approaches, and consider the intriguing interplay between physical and digital (online) experiences. Taken together, the various examples reviewed here help to illustrate the growing commercial relevance of sonic seasoning research.