Effect of a pre-hydrolysis on the in vitro digestibility of Arthrospira platensis
Résumé
Spirulina, a cyanobacteria that is 60% protein, could provide an alternative to animal proteins,
the production of which is a major contributor to greenhouse gas emissions. Protein from this
organism, which is also rich in vitamins and minerals, has good amino acid profile and contains
bioactive activities. However, its digestibility has been poorly assessed and varies greatly from one
study to another. Moreover, spirulina protein digestibility remains lower than that of animal proteins.
One possibility to improve spirulina digestibility is to pre-hydrolyze the proteins into peptides using
various proteases. Additionally, pre-hydrolysis of Spirulina by various enzymes could significantly
increase spirulina protein digestibility.
In this study, alcalase and bromelain were used at different concentrations (0.25% and 1%) to
pre-hydrolyze dry or frozen spirulina. Samples were analyzed by size exclusion chromatography and
mass spectrometry before digestion. Then, the INFOGEST in vitro static digestion model was used to
assess spirulina digestibility and free amino acids were assayed after digestion. Pre-hydrolysing
spirulina did not improve significantly protein digestibility, which stands at around 81%. However,
qualitative differences were observed in the pre-hydrolyzed solutions before and after digestion. In
particular, peptide size varied according to the enzyme used (alcalase vs bromelain), its concentration
(0.25% vs 1%), and the storage method (dry or frozen spirulina). Additionally, at the end of the gastric
phase, bioactive peptides could be identified although they were still encrypted in longer sequences