Although human perception of food flavors involves integration of multiple sensory inputs, the most salient sensations are taste and olfaction. Ortho- and retronasal olfaction are particularly crucial to flavor because they provide the qualitative diversity so important to identify safe versus dangerous foods. Historically, flavor research has prioritized aroma volatiles present at levels exceeding the orthonasally measured odor threshold, ignoring the variation in the rate at which odor intensities grow above threshold. Furthermore, the chemical composition of a food in itself tells us very little about whether or not that food will be liked. Clearly, alternative approaches are needed to elucidate flavor chemistry. Here we use targeted metabolomics and natural variation in flavor-associated sugars, acids, and aroma volatiles to evaluate the chemistry of tomato fruits, creating a predictive and testable model of liking. This nontraditional approach provides novel insights into flavor chemistry, the interactions between taste and retronasal olfaction, and a paradigm for enhancing liking of natural products. Some of the most abundant volatiles do not contribute to consumer liking, whereas other less abundant ones do. Aroma volatiles make contributions to perceived sweetness independent of sugar concentration, suggesting a novel way to increase perception of sweetness without adding sugar.

Fresh strawberries (Fragaria x ananassa) are valued for their characteristic red color, juicy texture, distinct aroma, and sweet fruity flavor. In this study, genetic and environmentally induced variation is exploited to capture biochemically diverse strawberry fruit for metabolite profiling and consumer rating. Analyses identify fruit attributes influencing hedonics and sensory perception of strawberry fruit using a psychophysics approach. Sweetness intensity, flavor intensity, and texture liking are dependent on sugar concentrations, specific volatile compounds, and fruit firmness, respectively. Overall liking is most greatly influenced by sweetness and strawberry flavor intensity, which are undermined by environmental pressures that reduce sucrose and total volatile content. The volatile profiles among commercial strawberry varieties are complex and distinct, but a list of perceptually impactful compounds from the larger mixture is better defined. Particular esters, terpenes, and furans have the most significant fits to strawberry flavor intensity. In total, thirty-one volatile compounds are found to be significantly correlated to strawberry flavor intensity, only one of them negatively. Further analysis identifies individual volatile compounds that have an enhancing effect on perceived sweetness intensity of fruit independent of sugar content. These findings allow for consumer influence in the breeding of more desirable fruits and vegetables. Also, this approach garners insights into fruit metabolomics, flavor chemistry, and a paradigm for enhancing liking of natural or processed products.

Studies were conducted to describe flavor and aroma in ripe tomatoes stored at 5, 10, 12.5 and 20°C. Fruit stored for 2 d below 20°C were rated by trained sensory panelists as significantly lower (P < 0.05) in ripe aroma, tomato flavor, compared to those stored at 20°C. Fruit stored at 5°C for 4 d were rated significantly lower in ripe aroma, sweetness, tomato flavor, and significantly higher in sourness, compared to those stored at 20°C. Following 8 and 12 d storage, fruit at 5°C were rated lowest in ripe aroma and sweetness. Significant reductions in important GC aroma volatiles and chemical composition and electronic nose analyses concurred with sensory descriptor ratings.

Several chemicals were negatively correlated with at least one of the hedonic scores while several others were positively correlated with tomato flavor acceptability. The results permitted identification of positive and negative interactions of volatiles with tomato flavor.

In many flowering plants, such as petunia (Petunia 3 hybrida), ethylene produced in floral organs after pollination elicits a series of physiological and biochemical events, ultimately leading to senescence of petals and successful fertilization. Here, we demonstrate, using transgenic ethylene insensitive (44568) and Mitchell Diploid petunias, that multiple components of emission of volatile organic compounds (VOCs) are regulated by ethylene. Expression of benzoic acid/salicylic acid carboxyl methyltransferase (PhBSMT1 and 2) mRNA is temporally and spatially down-regulated in floral organs in a manner consistent with current models for postpollination ethylene synthesis in petunia corollas. Emission of methylbenzoate and other VOCs after pollination and exogenous ethylene treatment parallels a reduction in PhBSMT1 and 2 mRNA levels. Under cyclic light conditions (day/night), PhBSMT mRNA levels are rhythmic and precede emission of methylbenzoate by approximately 6 h. When shifted into constant dark or light conditions, PhBSMT mRNA levels and subsequent methylbenzoate emission correspondingly decrease or increase to minimum or maximum levels observed during normal conditions, thus suggesting that light may be a more critical influence on cyclic emission of methylbenzoate than a circadian clock. Transgenic PhBSMT RNAi flowers with reduced PhBSMT mRNA levels show a 75% to 99% decrease in methylbenzoate emission, with minimal changes in other petunia VOCs. These results implicate PhBSMT1 and 2 as genes responsible for synthesis of methylbenzoate in petunia.Many flowers exhibit a colorful display of petals and emit a complex mixture of floral volatile organic compounds (VOCs) that are together attractive to both pollinators and humans. Regulation of floral volatiles corresponds to pollinator activity times and receptivity of the flower to a pollination event (Dudareva et al., 2000;Schiestl and Ayasse, 2001). In many flowers, physiological changes take place following pollination and fertilization including petal wilting and abscission, color changes, flower closure, fruit development, and seed development (for review, see O'Neill, 1997). The plant hormone ethylene has been shown to coordinate several of these postpollination processes in many different plant species (van Doorn, 1997).In many plants, ethylene is synthesized and perceived in a localized, specific, and reproducible manner after pollination, underscoring the importance of understanding the progression of events and role of ethylene during pollination and fertilization. Petunia (Petunia 3 hybrida) is an excellent model system for studying postpollination responses because ethylene synthesis has been well characterized (Hoekstra and Weges, 1986;Tang and Woodson, 1996;Jones et al., 2003) and components of the ethylene-signaling pathway have been investigated (Wilkinson et al., 1997;Shibuya et al., 2004). In petunia, ethylene synchronizes pollen tube growth (Holden et al., 2003) and petal wilting (Hoekstra and Weges, 1986;Gubrium et al., 2000). An initial bur...