Sex Differences in the Bitterness Perception of an Aromatic Myrtle Bitter Liqueur and Bitter Compounds

Abstract

We evaluated sex differences in the perception of bitter compounds and an aromatic bitter herbal liqueur (Mirtamaro) obtained by the infusion of myrtle leaves/berries together with a mixture of Mediterranean herbs/plants as flavoring/bittering ingredients. In a healthy population (n = 231 participants), using bivariate correlations and multivariate linear regression analyses, significant sex differences emerged in quinine bitterness perception, with women showing a higher bitter taste intensity rating than men. Among all participants, 40 subjects (subpopulation) were randomly selected for the evaluation of sex differences in Mirtamaro gustatory and olfactory perception using a hedonic Likert-type scale. Women showed higher ratings in Mirtamaro aroma (odor intensity) and bitterness (taste intensity) perception than men, with a superior capacity to perceive/describe its sensory attributes. 1,8-Cineole and methyl chavicol were the main contributors to the bitter liqueur aroma. A significant correlation (r = 0.564, p < 0.01) between Mirtamaro odor pleasantness/taste pleasantness was observed in women, indicating a positive contribution of aromatic herbs to bitter taste acceptability. Moreover, a higher bitter intensity rating of 6-n-propylthiouracil was evidenced in women than men. Our results highlighted sex differences in bitter taste acuity and the role of aromatic herbs/plants in modulating bitter taste acceptance, which is useful information in the field of precision nutrition and medicine.

Keywords: aromatic herbs and plants; bitter liqueur; bitter perception; myrtle; quinine.

Figure 1

(A) Digital image of aromatic myrtle herbal liqueur (Mirtamaro). (B) Extraction of Mirtamaro with n-hexane.

Figure 2

Mean values ± standard deviation of sweet, salty, sour, and bitter (quinine) taste scores measured in total subjects (Total, n = 231), men (n = 78), and women (n = 153). For each taste modality (sweet, salty, sour, and bitter): * = p < 0.05, ** = p < 0.01 for men versus women (Student’s unpaired t-test with Welch’s correction) (A). Patterns of subjects’ bitterness perception, expressed as percentual values (%), of each bitter (quinine) taste score (0, 1, 2, 3, and 4), assessed in men (B) and women (C).

Figure 3

Mean values ± standard deviation (SD) of quinine and PROP taste scores measured in total subjects (Total, n = 40), men (n = 14), and women (n = 26); ** = p < 0.01, * = p < 0.05 for men versus women (Student’s unpaired t-test with Welch’s correction) (A). Patterns of subjects’ bitterness perception, expressed as percentual values (%) of each quinine (0, 1, 2, 3, and 4) and PROP (0, 1, 2, and 3) taste score, determined for quinine in men (B) and women (C) and for PROP in men (D) and women (E).

Figure 4

Ratings of odor pleasantness (P), intensity (I), and familiarity (F) dimensions of the aromatic myrtle herbal liqueur (Mirtamaro) measured in total subjects (Total, n = 40), men (n = 14), and women (n = 26). Data are presented as mean values and standard deviations; ** = p < 0.01 for men versus women (Student’s unpaired t-test with Welch’s correction) (A). Patterns of subjects’ odor intensity perception of Mirtamaro, expressed as percentual values (%) of each odor intensity score (0, 1, 2, 3, 4, 5, and 6), determined for men (B) and women (C).

Figure 5

Ratings of taste pleasantness (P), intensity (I), and familiarity (F) dimensions of the aromatic myrtle herbal liqueur (Mirtamaro) measured in total subjects (Total, n = 40), men (n = 14), and women (n = 26). Data are presented as mean values and standard deviations; ** = p < 0.01 for men versus women (Student’s unpaired t-test with Welch’s correction) (A). Patterns of subjects’ taste intensity perception of Mirtamaro expressed as percentual values (%) of each taste intensity score (0, 1, 2, 3, 4, 5, and 6), determined for men (B) and women (C).

Figure 6

Chromatographic profiles by GC-FID of n-hexane extract obtained from the aromatic myrtle herbal liqueur (Mirtamaro). Chemical structures of the main volatile organic compounds are also reported.