From greenhouse production to consumer choices: the role of zinc biofortification and visual cues

Innovation in fresh vegetables increasingly combines visible differentiation, such as novel colours, with process-based improvements, such as mineral biofortification. When nutritional enhancements are not visually detectable, consumer responses depend on how visible and invisible cues are perceived and processed in the decision-making process. This study investigates the concurrent role of fruit colour (visible attribute) and zinc (Zn) biofortification (invisible credence attribute) in shaping preferences for fresh mini plum tomatoes. A greenhouse experiment was conducted to ensure the internal validity of the consumer study by testing whether foliar Zn-EDTA applications affect visually perceivable traits. The resulting products were then used to elicit consumer preferences through a lab-based real-choice discrete choice experiment (n = 198), involving binding purchase decisions and complemented by eye-tracking data to capture visual attention. Results indicate that colour is the primary driver of both attention and choice, with brownish and mixed assortments attracting more gaze and purchases than red-only options. A latent class model identifies three distinct consumer segments: two innovation-oriented groups willing to pay for biofortification and novel colours, and a conservative segment averse to both attributes and exhibiting signs of visual overload. Overall, the findings show that visible cues dominate decision-making when credence attributes are not salient, and that eye-tracking enhances the interpretation of preference heterogeneity.