Masking of bitterness in lettuce (Lactuca sativa L.) by apple juice (Malus domestica Borkh.) in green smoothies - A pilot consumer study

While fruit smoothies are widely used to enhance fruit consumption, vegetable based green smoothies have not yet been systematically analyzed for consumer acceptance. Vegetable based green smoothies are often neglected due to their bitter and unpleasant taste or are masked with sweet fruits. This study investigates consumers' liking of 3 different smoothies with equal amounts of bitter lettuce and apple, but different portions of sweet apple juice, resulting in a decreasing bitter-compound-to-sugar ratio. Liking (9-point scales) of odor and taste, flavor perception (check-all-that-apply) and texture (just-about-right scale) were evaluated by 67 consumers. In the sweetest smoothie the descriptor ‘bitter’ was chosen almost 4 times less frequently than in the smoothie with the lowest sugar concentrations (medium effect size; Cohens D: 0.569). Detailed knowledge of bitter masking thresholds may help to balance between bitter masking and limited use of highly caloric ingredients in healthy green smoothies.