Impact of cooking and food matrix structure on the nutritional profile of quinoa leaf protein extracts assessed by the INFOGEST static in vitro digestion method

Proteins are essential macronutrients with increasing global demand. Green leaves have been proposed as a promising source of alternative proteins. Chenopodium quinoa leaves were used in this work to produce quinoa leaf protein concentrates (QPC) containing RuBisCO. The protein nutritional quality was assessed using the INFOGEST static in vitro digestion method, and the effects of cooking and gelling on protein digestibility determined. The protein extract showed high protein digestibility (>95%), regardless of the applied cooking treatment or the formulation of the solid gels. Additionally, the digestible indispensable amino acid score ( in vitro DIAAS) exceeded 100%, representing a good source of essential amino acids. The protein digests obtained after the gastric and intestinal phases were further characterized using confocal laser scanning microscopy (CLSM), which confirmed that the food matrices were broken down during the digestion process. Additionally, anti-nutritional factors were investigated by putative identification of 16 saponins in the QPC using LC-MS. These compounds did not exhibit any inhibitory effect on trypsin activity. The study demonstrates the potential of QPC as a promising source of protein with the right composition of essential amino acids and high protein digestibility, with application in the formulation of different food matrices.