In vitro protein digestibility of RuBisCO from alfalfa obtained from different processing histories: Insights from free N-terminal and mass spectrometry study

Ribulose-1,5-bisphosphate-carboxylase/oxygenase (RuBisCO) from alfalfa is a potentially climate-friendly alternative protein with a promising amino acid composition. The balance between yield and purity is a challenge for alternative plant proteins, partly due to the naturally occurring antinutrients. Therefore, measuring the in vitro protein digestibility (IVPD) of RuBisCO with various purity levels is of interest. It was hypothesized that the digestibility of RuBisCO from alfalfa might vary with different processing histories and levels of refinement. To test this hypothesis, RuBisCO from alfalfa with 4 different processing histories were subjected to the INFOGEST IVPD protocol and measurement of free N-terminals and peptidomics. The result showed that the digestibility of RuBisCO was high regardless of the processing history and purity, as demonstrated by 77–99% sequence coverage in the gastric phase. In intestinal phase, increase of free N-terminals and lower sequence coverage (< 10%) indicated that the proteins were hydrolyzed to smaller peptides.