Exploitation of lettuce waste flour to increase bread functionality: effect on physical, nutritional, sensory properties and on consumer response

Phenol and fibre-rich flour obtained by air-drying and grinding of lettuce waste was partially substituted (26, 53, 170 and 575 g/kg) with wheat flour to produce functional bread. The addition of flour progressively decreased dough leavening capacity while increased bread moisture and firmness. Lettuce waste flour significantly increased the polyphenolic content (up to 3.4 g GAE/kg) of bread samples and enhanced their antioxidant activity by 200%. Bread containing 170 g/kg and 575 g/kg of lettuce waste flour presented sensory properties and consumer acceptability comparable to those of commercial wholemeal bread with similar rye bran content. Bread containing at least 170 g/kg of lettuce waste flour could be associated to nutritional claims related to its enhanced fibre content (>30 g/kg). Data obtained by conjoint analysis demonstrate the possibility of increasing consumer preference for lettuce waste flour bread by proper nutritional (fibre content) and sustainability (lettuce waste valorisation) claims.