Effect of pre-treatment on in vitro gastric digestion of quinoa protein (Chenopodium quinoa Willd.) obtained by wet and dry fractionation.

Quinoa protein was isolated from quinoa seeds using wet fractionation that resulted in a protein isolate (QPI) with a high protein purity of 87.1% (w/dw) and a protein yield of around 54%, and a dry fractionation method delivered a quinoa protein concentrate (QPC) with a purity of 27.8% (w/dw) and yield of around 47%. The dry fractionation process only involves milling and sieving and keeps the protein in its natural, native state. The aim was to study the in vitro gastric digestibility of both protein. Attention was paid to thermal pre-treatment of QPI and QPC. QPC showed significantly higher (p < .05) digestibility than QPI samples. The results were interpreted with a simple double exponential model. The fraction of easily digested protein in QPC is higher than for QPI. The better digestibility of the QPC was explained by the prevention of the formation of large aggregates during pre-heating of the protein.