Introduction: Legume Processing

Legumes consist of pulses (several types of beans, chickpeas, lentils and peas) and non-pulses (peanuts and soybeans). They are a good source of starch, protein and fibre for humans, consumed worldwide as staple food. The nutritional profile vary based on the legume type, cultivars and origin. Starch is the main component of pulses, representing about 50–75 g/100 g (in common beans and lima beans, respectively). On the contrary, soybeans only contain 10 g/100 g starch, in favour of more fibre (20 vs. 10 g/100 g) and, most significantly, protein: 41 vs. 15–25 g/100 g. Lipids are moderate in chickpeas and abundant in peanuts and soybeans: 50 and 20 g/100 g. Consumption occurs upon processing such as soaking, boiling and milling. When used as flours, legumes develop stable foams, emulsify and absorb water and oil. Foaming ability ranges from 40% to 175%, while the emulsifying activity index spans from 10 to 18 m2/g. Finally, water absorption capacity exceeds oil absorption: 1.3–6.7 g/g vs. 0.9–2.2 g/g, respectively. Protein supports foaming and emulsifying ability, while a combination of carbohydrates and protein contributes to the thickening abilities. This chapter provides an overview on legumes in terms of nutritional value and functionality as food ingredients.