Bioactive peptides from shrimp shell processing discards: Antioxidant and biological activities

- Shrimp shell processing discards were used to prepare protein hydrolysates.
- Hydrolysates exhibited radical scavenging and ferrous ion chelating abilities.
- Hydrolysates exhibited antioxidant activities in biological systems (LDL and DNA).
- Shrimp shell discard hydrolysates exhibited ACE inhibitory activity.
- Three potential ACE inhibitory bioactive peptides were identified form shrimp shell discards.

Protein hydrolysates were prepared from shrimp discards, using various enzymes, which were subsequently analyzed for their antioxidant potential and biological activities. Raw shrimp shell discards hydrolysates (RSH) and isolated shrimp shell protein hydrolysates (SPH) exhibited radical scavenging activities (ABTS, DPPH and hydroxyl), reducing power and ferrous ion chelating ability. In addition, RSH and SPH inhibited beta-carotene bleaching in an oil-in-water emulsion, cupric ion induced LDL cholesterol peroxidation as well as peroxyl and hydroxyl radical induced DNA strand scission effectively. In-vitro determination of ACE inhibitory activity by RSH and SPH showed that these hydrolysates could be used in supplements, foods or in the purified form as potential pharmaceuticals for blood pressure control. Moreover, shrimp shell discard protein hydrolysate fractions with highest ACE inhibitory activity were further subjected to gel filtration, mass spectrometry and peptide sequencing. Three potential ACE inhibitory bioactive peptides were identified form shrimp shell discard for the first time.