Identification of peptides released from hot water insoluble fraction of edible bird's nest under simulated gastro-intestinal conditions

• Peptides from hot water insoluble fraction of bird's nest (HWIF) were identified.
• HWIF was readily digested by simulated gastric fluid.
• HWIF was hardly digested further by simulated intestinal fluid.
• The released peptides shared very high similarities to many interesting proteins.

For centuries, edible bird's nest (EBN) has been consumed as a Chinese delicacy. In the past decades, numerous studies reported that water soluble extract of the EBN not only possessed epidermal growth factor, but also associated with a wide range of health-promoting effects. However, based on the traditional Chinese way of EBN preparation and consumption, the bioactive components should be originated from both its hot water soluble and insoluble fractions. Nevertheless, information on the hot water insoluble fraction (HWIF) of EBN is not currently available. In this study, peptides released from the HWIF of EBN under simulated gastro-intestinal conditions were identified for the first time by de novo sequencing using a combination of MALDI TOF/TOF MS and ESI-ion-trap MS/MS. The released peptides were found to share very high similarities to mucin, NADH dehydrogenase, acidic mammalian chitinase-like protein, immunoglobulin, proline-rich protein, von Willebrand factor and epidermal growth factor domain-containing protein.