Interactions between retronasal olfaction and taste influence vegetable liking and consumption: A psychophysical investigation

Abstract

Previously, we found bitter and sweet tastes to be positive and negative predictors of vegetable liking and intake. Here, we examined interactions between retronasal olfactory sensations (flavor) and tastes as potential predictors of vegetable liking and intake. Adults (n = 97), diverse in bodyweight (40% overweight/obese), rated green vegetables (asparagus, Brussels sprouts, kale) for flavor (sampled with nose plugged, then unplugged to perceive flavor volatiles) and tastes (bitterness and sweetness). They were phenotyped for genetic variation in taste (propylthiouracil (PROP) bitterness) and taste function (quinine bitterness on the tongue tip relative to whole mouth); vegetable consumption frequency was self-reported. Greater increases in vegetable flavor sensations (difference of nose unplugged v. plugged) were associated with greater vegetable bitterness but not sweetness. Those tasting PROP as most bitter also reported greater flavor sensations (nose unplugged) but not greater flavor increases (difference of unplugged v. plugged). With retronasal flavor input, hedonic ratings increased significantly for asparagus, showed little change for kale, and were highly variability for Brussels sprouts; these ratings did not vary by taste phenotype. Those with greater body mass index reported more hedonic increases with vegetable flavor (difference of unplugged v. plugged). In multivariate modeling, PROP bitterness directly predicted vegetable bitterness and flavor. Vegetable flavor negatively influenced vegetable liking and intake indirectly via bitterness, and showed direct negative effects on vegetable intake. These findings support the need for basic and applied research across the food system (e.g., farm to table) to identify ways to enhance pleasant oral sensations from vegetables (e.g., sensory-guided breeding). More pleasant oral sensations would encourage vegetable consumption in support of healthy eating and body weight, especially for individuals with genetic propensity to experience negative oral sensations from vegetables.