Visual cues have been reported to influence taste and flavor perceptions. The objectives of this study were to evaluate the impact of visual cues (color and viscosity) of syrups on expected sweetness and bitterness perception (Study I), and on sweetness perception and sweetness liking of brewed coffee after syrup had been added, and the amount of syrups to be added to brewed coffee (Study II). For Study I, the visual stimuli were developed by varying viscosity (80, 800, and 8000 cP) and yellow index (YI) (0.04, 0.08, 0.16, and 0.32), resulting in 12 syrups with 20 degrees Brix. Visual observations indicated greater expected sweetness perceptions of syrups when YI and viscosity were increased. However, YI, but not viscosity, affected expected bitterness perceptions. Increasing YI raised the frequency (%) of "too sweet" perceptions of syrups on a JAR scale. For Study II, only four syrups (LC1, LC2, HC1, HC2; L = viscosity, 80 cP, H = 8,000 cP; C1 = YI 0.04, C2 = YI 0.32) were studied. The visual perception affected consumers' behaviors concerning the amount of syrup added to brewed coffee. Consumers added the greatest volume of syrups with the lowest viscosity and YI (LC1), while the lowest volume of syrups with the highest viscosity and YI (HC2). There were no significant differences in sweetness liking of brewed coffees added with LC1, LC2, and/or HC1 syrups. This study indicated that visual cues could potentially intensify the perceived sweetness of syrups, and reduced the volume of syrup added to brewed coffee and consequently calories consumed. PRACTICAL APPLICATION: Sensory visual cues associated with a syrup can be used to reduce the volume consumed and thereby promote reduced consumption of calories while maintaining sensory acceptability. Increasing a syrup's viscosity and yellow/brown color intensity enhanced the expectation of sweetness and resulted in less volume of syrup added to brewed coffee. This research demonstrated that the impact of visual cues not only influenced expectation and sensory acceptability but also impacted the cognitive process of eating. This strategy could provide a way to promote a sustainable reduction in sugar and, hence, calorie consumption without compromising sensory liking.
Keywords: coffee; reduced sugar consumption; sweetness; taste expectation; visual cues.
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