What Makes Lupins Less Palatable to Consumers? Can the Sensory Quality of Lupin be Improved and Commercialized?

Introducing underutilized legumes as plant-based protein sources to daily meals is an approach to address the increasing demand for alternative proteins. However, legumes often exhibit off-flavors and aromas, causing negative consumer perceptions. Lupins are an underutilized legume that is becoming popular as a plant protein source due to their high protein, fiber, and low starch contents. Off-flavor and off-aroma from what is believed to be lipoxygenase (LOX) activity make lupin-based food products less palatable. To introduce lupins as a food ingredient into mainstream products, its undesirable sensory traits, such as "beany," "green," and "grassy" flavors, need to be eliminated or reduced to levels that consumers cannot detect. This review discusses the compounds responsible for off-flavors, detection methods, current strategies to eliminate their formation and the possibility of developing lupin-based food products. Previous research has demonstrated the feasibility of developing different lupin-based food products such as fermented beverages, chapattis, bread, muffins, breakfast cereal, snacks, sausage, chips, ice creams, and flavored edible oils. Research attempts have also focused on the impact of different flavor modification treatments such as germination, fermentation, and different heat treatments to mask off-flavors. Of these, fermentation has the potential to reduce off-flavors to some extent, but not to a level where they are not completely detectable by consumers. To the best of our knowledge, this is the first comprehensive review of off-flavor issues in lupins, specifically Lupinus angustifolius L., offering insights to support the development of advanced off-flavor mitigation strategies for the effective use of lupin ingredients such as flour, protein isolates, concentrates, and flakes in industrial food applications.