Sensorial properties of red wine polyphenols: Astringency and bitterness

Role of Flavonols and Proanthocyanidins in the Sensory Quality of Sea Buckthorn (Hippophaë rhamnoides L.) Berries

Sensory profile, flavonols, proanthocyanidins, sugars, and organic acids were investigated in purees of six sea buckthorn (Hippophaë rhamnoides) cultivars. The sensory profiles of the purees were dominated by intense sourness followed by astringency and bitterness due to the high content of malic acid. Malic acid and isorhamnetin glycosides, especially isorhamnetin-3-O-sophoroside-7-O-rhamnoside, had close association with the astringent attributes in the different purees, whereas some of the known astringent compounds such as proanthocyanidin dimers and trimers or quercetin glycosides, had less impact. Moreover, the ratios between contents of acids and phenolic compounds were more important predictors of bitterness than the individual variables alone. Astringency and bitterness are important sensory factors for the consumer acceptance of sea buckthorn products. The current study provides new knowledge on the correlations between sensory properties and composition and supports industrial utilization of the sea buckthorn berries.

Aroma release in the oral cavity after wine intake is influenced by wine matrix composition

The aim of this study has been to investigate if wine matrix composition might influence the interaction between odorants and oral mucosa in the oral cavity during a "wine intake-like" situation. Aroma released after exposing the oral cavity of three individuals to different wines (n=12) previously spiked with six target aromas was followed by an -in vivo intra-oral SPME approach. Results showed a significant effect of wine matrix composition on the intra-oral aroma release of certain odorants. Among the wine matrix parameters, phenolic compounds showed the largest impact. This effect was dependent on their chemical structure. Some phenolic acids (e.g. hippuric, caffeic) were associated to an increase in the intra-oral release of certain odorants (e.g. linalool, β-ionone), while flavonoids showed the opposite effect, decreasing the intra-oral release of aliphatic esters (ethyl hexanoate). This work shows for the first time, the impact of wine composition on oral-mucosa interactions under physiological conditions.

Co-fermentation of red grapes and white pomace: A natural and economical process to modulate hybrid wine composition

The impact of co-fermenting white grape pomace (WP) and red grape pomace (RP) on the composition of interspecific hybrid wine was studied using the Vitis sp. 'Frontenac' and 'Vidal'. The proanthocyanidin and anthocyanin content of the resulting wines were analysed by HPLC-fluorescence and UPLC-MS/MS, respectively. The CIELAB parameters and volatile compounds were analysed using spectrophotometry-UV and GC-MS-SPME, respectively. The WP addition increased the concentration of monomeric and oligomeric flavan-3-ols, and terpenes in the wines. The manipulation of the WP/RP ratio efficiently modulated the anthocyanin profile of the wines, resulting in faded red colour, a desirable achievement in hybrid red wine, which is usually perceived as too dark. An appropriate ratio (30% RP/6% WP) improved the colour stability of the wines without a significant impact on wine colour. Addition of WP proved to be a suitable tool to modulate the colour, the phenolic and volatile composition of interspecific hybrid wine.

Association between taste receptor (TAS) genes and the perception of wine characteristics

Several studies have suggested a possible relationship between polymorphic variants of the taste receptors genes and the acceptance, liking and intake of food and beverages. In the last decade investigators have attempted to link the individual ability to taste 6-n-propylthiouracil (PROP) and the sensations, such as astringency and bitterness, elicited by wine or its components, but with contradictory results. We have used the genotype instead of the phenotype (responsiveness to PROP or other tastants), to test the possible relation between genetic variability and the perception of wine characteristic in 528 subjects from Italy and the Czech Republic. We observed several interesting associations, among which the association between several TAS2R38 gene single nucleotide polymorphisms (P = 0.002) and the TAS2R16-rs6466849 polymorphism with wine sourness P = 0.0003). These associations were consistent in both populations, even though the country of origin was an important factor in the two models, thus indicating therefore that genetics alongside cultural factors also play a significant role in the individual liking of wine.

A specific dose of grape seed-derived proanthocyanidins to inhibit body weight gain limits food intake and increases energy expenditure in rats

PURPOSE

Several studies have suggested that flavanols may have antiobesity effects; however, those effects clearly depend on the experimental conditions. In a previous study, we found that a single acute dose of grape seed proanthocyanidin extract (GSPE) has satiating effects. We therefore hypothesise that satiating doses of GSPE could be used to reduce body weight gain, and our present objective was to define the most effective dose.

METHODS

We assayed two GSPE doses in aged male Wistar rats. First we performed a subchronic (8-day) treatment by intragastric administration, which was repeated after a washout period. We measured body weight, energy intake and faeces composition; we performed indirect calorimetry; and we analysed the mRNA expression of genes involved in lipid metabolism to determine the target tissue for the GSPE.

RESULTS

We observed that 0.5 g GSPE/kg BW significantly reduced food intake and thus the amount of energy absorbed. This dosage also increased lipid oxidation in subcutaneous adipose tissue, thus causing a higher total energy expenditure. These combined effects caused a decrease in body weight. Conversely, 1 g GSPE/kg BW, which also reduced energy absorption after the first treatment, had a rebound effect on body weight gain which resulted in a lower response to the proanthocyanidin extract. That is, after the second treatment, the GSPE did not reduce the energy absorbed or modify energy expenditure and body weight.

CONCLUSION

GSPE at a dose of 0.5 g/kg can reduce body weight by limiting food intake and activating energy expenditure in subcutaneous adipose tissue.