Functionality-driven fractionation of lupin seeds

The growth in the world population requires an increase in the production of protein-rich foods from plant-based materials. Lupin seeds have potential to become a novel plant protein source for food products because they are rich in protein (about 37 wt%) and they can be grown in moderate temperature climates as in north-western Europe. Besides a high protein content, lupin seeds are rich in dietary fibres (soluble and insoluble), contain about 7-10 wt% oil, and are low in starch. To optimally use the proteins present in lupin, a fractionation process has to be developed. For other legumes, refining of protein is usually performed through wet fractionation techniques. However, wet fractionation methods are resource-intensive, as a result of which the potential reduction in environmental impact when using plant-based materials for foods decreases.

The aim of this thesis is to obtain understanding of the production of functional, protein-rich material from lupin seeds in a more efficient manner. In this thesis, it is shown that focus on functionality rather than purity can lead to simplified fractionation processes, which is a concept referred to as functionality-driven fractionation (Figure 1). The influence of these simplifications on protein functionality and on physical and chemical stability of the protein isolates was explored. Furthermore, we performed a sustainability assessment of fractionation processes, from which we concluded that focus on a dry product with high purity has a large impact on energy use. In case of lupin, avoiding the oil extraction step as well as the drying step could lead to large gains in sustainability.

Figure 1 Upper scheme: conventional ingredient production and product processing route, focusing on protein and yield. Lower scheme: novel approach, focusing on functionality and sustainability.

The results presented in this thesis provide steps towards more sustainable production of functional fractions for food applications obtained with simplified fractionation processes. This work provides future perspectives for functionality-driven fractionation processes that may be extended to other legumes and pulses as well. This approach leads to the development of ingredients and fractions of seeds and legumes that can be used for plant-based food products.