The replacement of cereals by legumes in extruded snack foods: Science, technology and challenges

Legumes contain several healthy essential nutrients and bioactive compounds, and their symbiotic nitrogen fixation ability confers substantial economic and environmental advantages. The traditional perception that legume flours are unsuitable for extrusion cooking is now proving to be outdated. Recent research suggests that legumes have great potential for replacing cereals in extruded snacks due to their healthier nutritional profile and remarkable functional characteristics. In this paper, the scientific and technological challenges associated with incorporating legume-based flours into extruded cereal-based snacks are reviewed. After comparing the nutritional properties of cereals and legumes, technological properties of extrudates (i.e. expansion ratio, bulk density, sensory properties etc.) enriched with legumes are explored. The current market situation and the future of legume-based extruded snacks are also discussed. Due to their functional characteristics, legume flours demonstrate good potential in the manufacture of extruded healthier snacks in which cereal flours are partially or entirely substituted. Lab-scale extrusion trials produce a wealth of information affirming that incorporating legume flours significantly affects the final extrudate structure and subsequent quality/sensory attributes of snacks. However, more work needs to be carried out to identify the most appropriate combination of flours and to optimise processing conditions to improve sensory and quality attributes and promote consumer acceptance. Increasing application of legumes in extruded snacks will continue to drive the global legumes market. •Legumes provide health benefits and economic and environmental advantages.•Legume flours are favourable ingredients in extruded cereal-based snacks.•Exploiting legume flours in extruded snacks still needs further development.•Innovations to mimic the taste and flavour of traditional snacks drives the market.