Impact of Dry Hopping on Beer Flavor Stability.

To investigate the chemical and sensorial impact of dry hopping time on typical pale ale, a standardized beer was produced and separated into ten vessels. Nine vessels were dry hopped, and one vessel remained un-hopped as a control. Impact of dry hopping contact time was investigated over 96 h. Polyphenols and iso-α-acid t/c ratio were analyzed in both Young and Aged beer samples. Total polyphenol content generally increased in both young and aged treatments compared to controls. Analysis of the t/c ratio suggests that both Young and Aged beers were chemically preserved to some degree after approximately 12 h at the given dry hopping rate regardless of age. Within the Aged beer trials, 96 h of dry hop contact yielded a significant increase in t/c ratio compared to all other Aged trials. This suggests that a 4-day dry hop regime may yield additional oxidative protection of iso-α-acids in beers stored unrefrigerated for 30 days. Descriptive analysis was also performed with an 8-person, trained panel; however, beers were sensorially distinguished by their aging time as opposed to their dry hopping time.

Understanding the Relationship between Red Wine Matrix, Tannin Activity, and Sensory Properties.

One major red wine mouthfeel characteristic, astringency, is derived from grape-extracted tannins and is considered to be a result of interaction with salivary proteins and the oral mucosa. To improve our understanding of the role that the enthalpy of interaction of tannin with a hydrophobic surface (tannin activity) has in astringency perception, a chromatographic method was used to determine the tannin concentration and activity of 34 Cabernet Sauvignon wines, as well as sensory analysis done on 13 of those wines. In addition, astringency-relevant matrix parameters (pH, titratable acidity, ethanol, glucose, and fructose) were measured across all wines. Tannin activity was not significantly correlated with any matrix variables, and the perception of drying and grippy was not correlated with tannin concentration and activity. However, ethanol content was well related to mouthfeel attributes and appeared to drive perceived drying. Although fructose and glucose content were well correlated, they did not drive the perception of sweetness, which is explained by the well-known mixture suppression effect.

Behavioral measures of risk tasking, sensation seeking and sensitivity to reward may reflect different motivations for spicy food liking and consumption.

Based on work a quarter century ago, it is widely accepted personality traits like sensation seeking are related to the enjoyment and intake of spicy foods; however, data supporting this belief is actually quite limited. Recently, we reported strong to moderate correlations between remembered spicy food liking and two personality traits measured with validated questionnaires. Here, participants consumed capsaicin-containing strawberry jelly to generate acute estimates of spicy food liking. Additionally, we used a laboratory-based behavioral measure of risk taking (the mobile Balloon Analogue Risk Task; mBART) to complement a range of validated self-report measures of risk-related personality traits. Present data confirm Sensation Seeking correlates with overall spicy meal liking and liking of the burn of a spicy meal, and extends prior findings by showing novel correlations with the liking of sampled stimuli. Other personality measures, including Sensitivity to Punishment (SP), Sensitivity to Reward (SR), and the Impulsivity and Risk Taking subscales of the DSM5 Personality Inventory (PID-5) did not show significant relationships with liking of spicy foods, either sampled or remembered. Our behavioral risk taking measure, the mBART, also failed to show a relationship with remembered or sampled liking. However, significant relationships were observed between reported intake of spicy foods and Sensitivity to Reward, and the Risk Taking subscale of the PID-5 (PID5-RT). Based on the observed patterns among various personality measures, and spicy food liking and intake, we propose that personality measures may exert their influence on intake of spicy food via different mechanisms. We also speculate that Sensation Seeking may reflect motivations for consuming spicy foods that are more intrinsic, while the motivations for eating spicy foods measured by SR and PID5-RT may be more extrinsic.

Gender differences in the influence of personality traits on spicy food liking and intake.

It has been proposed, and only minimally explored, that personality factors may play a role in determining an individual's sensitivity to and preference for capsaicin containing foods. We explored these relationships further here. Participants rated a number of foods and sensations on a generalized liking scale in a laboratory setting; after leaving the laboratory, they filled out an online personality survey, which included Arnett's Inventory of Sensation Seeking (AISS) and the Sensitivity to Punishment-Sensitivity to Reward Questionnaire (SPSRQ). Recently, we reported strong and moderate correlations between the liking of a spicy meal and the personality constructs of Sensation Seeking (AISS) and Sensitivity to Reward (SPSRQ), respectively. Here, we use moderation models to explore the relationships between personality traits, perceived intensity of the burn of capsaicin, and the liking and consumption of spicy foods. Limited evidence of moderation was observed; however differential effects of the personality traits were seen in men versus women. In men, Sensitivity to Reward associated more strongly with liking and consumption of spicy foods, while in women, Sensation Seeking associated more strongly with liking and intake of spicy foods. These differences suggest that in men and women, there may be divergent mechanisms leading to the intake of spicy foods; specifically, men may respond more to extrinsic factors, while women may respond more to intrinsic factors.

Personality factors predict spicy food liking and intake.

A number of factors likely affect the liking of capsaicin-containing foods such as social influences, repeated exposure to capsaicin, physiological differences in chemosensation, and personality. For example, it is well known that repeated exposure to capsaicin and chilies can result in chronic desensitization. Here, we explore the relationship between multiple personality variables - body awareness/consciousness, sensation seeking, and sensitivity to punishment, and sensitivity to reward - and the liking and consumption of capsaicin-containing foods. As expected, a strong relationship was found between liking of spicy foods and frequency of chili consumption. However, no association was observed between frequency of chili consumption and the perceived burn/sting of sampled capsaicin. Nor was there any association between perceived burn/sting of capsaicin and any of the personality measures. Private Body Consciousness did not relate to any of the measures used in the current study. Sensation Seeking showed positive correlations with the liking of spicy foods, but not non-spicy control foods. Sensitivity to Punishment showed no relation with frequency of chili consumption, and nonsignificant negative trends with liking of spicy foods. Conversely, Sensitivity to Reward was weakly though significantly correlated with the liking of a spicy meal, and similar nonsignificant trends were seen for other spicy foods. Frequency of chili consumption was positively associated with Sensation Seeking and Sensitivity to Reward. Present data indicate individuals who enjoy spicy foods exhibit higher Sensation Seeking and Sensitivity to Reward traits. Rather than merely showing reduced response to the irritating qualities of capsaicin as might be expected under the chronic desensitization hypothesis, these findings support the hypothesis that personality differences may drive differences in spicy food liking and intake.

Role of amino acid hydrophobicity, aromaticity, and molecular volume on IAPP(20-29) amyloid self-assembly.

Aromatic amino acids strongly promote cross-ß amyloid formation; whether the amyloidogenicity of aromatic residues is due to high hydrophobicity and ß-sheet propensity or formation of stabilizing π-π interactions has been debated. To clarify the role of aromatic residues on amyloid formation, the islet amyloid polypeptide 20-29 fragment [IAPP(20-29)], which contains a single aromatic residue (Phe 23), was adopted as a model. The side chain of residue 23 does not self-associate in cross-ß fibrils of IAPP(20-29) (Nielsen et al., Angew Chem Int Ed 2009;48:2118-2121), allowing investigation of the amyloidogenicity of aromatic amino acids in a context where direct π-π interactions do not occur. We prepared variants of IAPP(20-29) in which Tyr, Leu, Phe, pentafluorophenylalanine (F5-Phe), Trp, cyclohexylalanine (Cha), α-naphthylalanine (1-Nap), or ß-naphthylalanine (2-Nap) (in order of increasing peptide hydrophobicity) were incorporated at position 23 (SNNXGAILSS-NH2), and the kinetic and thermodynamic effects of these mutations on cross-ß self-assembly were assessed. The Tyr, Leu, and Trp 23 variants failed to readily self-assemble at concentrations up to 1.5 mM, while the Cha 23 mutant fibrillized with attenuated kinetics and similar thermodynamic stability relative to the wild-type Phe 23 peptide. Conversely, the F5-Phe, 1-Nap, and 2-Nap 23 variants self-assembled at enhanced rates, forming fibrils with greater thermodynamic stability than the wild-type peptide. These results indicate that the high amyloidogenicity of aromatic amino acids is a function of hydrophobicity, ß-sheet propensity, and planar geometry and not the ability to form stabilizing or directing π-π bonds.