Impact of apple procyanidins on sensory perception in model cider (part 2): Degree of polymerization and interactions with the matrix components

The impact of the degree of polymerization (DP) of procyanidins and its interactions with fructose, acidity and alcohol in a model solution of cider was investigated. Four sensory characteristics (bitterness, astringency, sweetness and sourness) were studied. At 750 mg/L of procyanidins, the DP impacted astringency and bitterness but not sweetness or sourness. The medium DP (tetramer) of apple procyanidins was the most bitter and astringency increased with the DP. The impact of ethanol, fructose and acidity on the four sensory attributes was also examined. These results provide insights into how the components interact to produce the taste of cider.     

Thermodynamics of the interaction of sweeteners and lactisole with fullerenols as an artificial sweet taste receptor model

The thermodynamics of the mimetic interaction of lactisole and sweeteners with fullerenols as a synthetic sweet receptor model was elucidated by Isothermal Titration Calorimetry (ITC) technique. The presence of lactisole resulted in great differences in thermodynamics of the sweeteners binding with fullerenols in which lactisole led to much more entropy contribution to the free energy compared with the interaction of sweeteners with fullerenols. Two interaction equilibrium states were found in ITC titration profiles and competitive binding of lactisole and sweeteners with fullerenols was disclosed. Our results indicated that the larger value of the ratio of two equilibrium constant K₁/K₂, the more effectively lactisole inhibited the sweetness of the sweetener. The combined results of sensory evaluation and ITC thermodynamics revealed that introducing a synthetic receptor model to interact with the sweeteners and inhibitors helps to understand the inhibition mechanism and the thermodynamic basis for the initiation of sweetness inhibition.     

The effect of modifying the distribution of sucralose and quinine on bitterness suppression in model gels

This study investigated the effect of simultaneously manipulating the spatial distribution of a sweet masking agent and bitter tastant within gelatine–agar gels on bitterness suppression, using sucralose and quinine. Sixty subjects participated in a series of paired comparison tests comparing different gel designs containing both sucralose and quinine, against a homogeneous control gel of identical overall sucralose (0.3 mM) and quinine content (0.3 mM). Twenty subjects also determined the bitterness reduction achieved in the homogeneous control gel by the addition of 0.3 mM sucralose to 0.3 mM quinine. Separating quinine and sucralose into different portions of the gel had no influence on bitterness suppression. Inhomogeneously distributing the quinine and sucralose into the same parts of the gel reduced the effectiveness of bitterness suppression. Inhomogeneously distributing the sucralose, while maintaining a homogeneous distribution of quinine, had no influence on bitterness suppression. Although an inhomogeneous distribution of sucralose increased sweetness perception and the addition of sucralose (0.3 mM) was found to substantially reduce bitterness in the homogeneous control, bitterness suppression was not enhanced when distributing the masking agent (sucralose) inhomogeneously.     

Understanding extraverts' enjoyment of social situations: The importance of pleasantness.

Extraversion is a broad, multifaceted trait, yet researchers are still unsure of its defining characteristics. One possibility is that the essential feature of extraversion is the tendency to enjoy social situations. An alternative possibility is that extraversion represents sensitivity to rewards and the tendency to experience pleasant affect. In three studies, participants rated situations that varied on two dimensions: (a) whether they were social or nonsocial and (b) whether they were very pleasant, moderately pleasant, moderately unpleasant, or very unpleasant. Extraverts only rated social situations more positively than introverts did when the situations were pleasant, and extraverts also rated nonsocial situations more positively than introverts did if the situations were pleasant. Thus, the pleasantness of situations was more important than whether they were social or nonsocial in determining extraverts' and introverts' enjoyment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Research on color harmony of building façades

In this study, the 28 primary colors and 11 complementary colors suggested by Chang et al in their investigation on building colors in Wanhua District of Taipei City were taken as color samples. The two-color combination mode was adopted to obtain 308 simulation photos, and two-color harmony was discussed from the perspective of visual evaluation using psychophysical tests. This study explored building façade color harmony in the CIELAB color space, and the relationship between the color attributes (hue, lightness, and chroma) and the color harmony, and between the differences of the color attributes and color harmony. It found that a high lightness of a building's primary color is associated with a high level of building color harmony, while the color harmony is reduced when the color falls in the green or blue sector in the CIELAB color space; a greater lightness difference between building façade colors is associated with a higher level of building color harmony, while the colors are disharmonized when they tend to the blue sector in the CIELAB color space. The contribution of this study is to summarize the principles for the application of building color harmony in urban renewal, and proposed suggestions on building color harmony in the urban renewal process.     

Relationships between musical structure and psychophysiological measures of emotion.

Psychophysiological studies with music have not examined what exactly in the music might be responsible for the observed physiological phenomena. The authors explored the relationships between 11 structural features of 16 musical excerpts and both self-reports of felt pleasantness and arousal and different physiological measures (respiration, skin conductance, heart rate). Overall, the relationships between musical features and experienced emotions corresponded well with those known between musical structure and perceived emotions. This suggests that the internal structure of the music played a primary role in the induction of the emotions in comparison to extramusical factors. Mode, harmonic complexity, and rhythmic articulation best differentiated between negative and positive valence, whereas tempo, accentuation, and rhythmic articulation best discriminated high arousal from low arousal. Tempo, accentuation, and rhythmic articulation were the features that most strongly correlated with physiological measures. Music that induced faster breathing and higher minute ventilation, skin conductance, and heart rate was fast, accentuated, and staccato. This finding corroborates the contention that rhythmic aspects are the major determinants of physiological responses to music. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Residue mutations in the sweetness loops for the sweet-tasting protein brazzein

To identify critical residues, important for sweetness, of the sweet protein brazzein, 11 mutants of the residues in three loops of brazzein were constructed by site-directed mutagenesis. We found that mutations of Glu41 to Ala, Lys, or Arg at position 41 in loop 40–43 made the molecules significantly sweeter than brazzein, while mutations at two distant residues (changing Arg43 to Lys or Glu) decreased sweetness. A similar pattern occurred at loop 30–33, where mutation of the His31 to Arg significantly increased sweetness, while mutations at positions 30 or 33 in the immediate vicinity of this region significantly decreased sweetness. In addition, a Gln17 residue in the loop 9–19 was necessary for structural integrity. From these results, we suggest that the loops containing His31 and Glu41 are critical regions of the molecule for eliciting sweetness, and the charge and/or structure of the side chain of these residues play an important role in the multi-point interactions between brazzein and the sweet-taste receptor.