Bioactive peptides from Boarfish: Protein extraction and generation of .... Ireland), Papain from Carica papaya (Sigma, Dublin, Ireland) and Protease AP supplied ...
Bioactive peptides from Boarfish: Protein extraction and generation of health beneficial peptide hydrolysates using established techniques Hayes, M.1 & Fagan, J.2 1Teagasc
Food Research Centre, Ashtown, Dublin 15, Ireland. 2Bord Iascaigh Mhara, Seafood Development Centre, Clonakilty, Co. Cork, Ireland.
METHODS
INTRODUCTION Current global protein production for a rising population will not be sustainable given the yields and use of current protein crops. A number of protein sources are available for further development and these include marine sources such as macroalgae and underutilised fish species. Protein rich by-catch is discarded or processed into fishmeal. Boarfish (Capros aper) (Figure 1) is an underutilized fish species that are present in abundance in Irish fishing waters. Indeed, Ireland secured the majority of the EU quota for Boarfish in 2011 and significant numbers have been collected in Irish waters since 20011. Global demand for protein is ever increasing due to expanding world populations. Marine discard and underutilized fish species can be converted into high economic value marine ingredients using biotechnological processes.
RESULTS
A common extraction method used for the generation of fish proteins is solvent extraction. In this study, the chemical shift isolation method was used3. 1.3 Kg of freeze-dried Boarfish was added to 2 litres of water and the pH was adjusted to pH 11 with 3M NaOH. The first protein extraction was carried out for 15 minutes and the sample was centrifuged for 15 minutes at 4˚C. The pellet was suspended in 2 liters of water and the pH adjusted to 11 with 3M NaOH. This produced fraction A. The second protein extraction was carried out for 60 minutes and the sample was then centrifuged as with fraction A. The pellet was suspended in 2 litres of water and the pH adjusted to 2 with 3M HCL. The third extraction was carried out for 15 mins and centrifuged. The supernatants were pooled and pH adjusted using NaOH. The samples were allowed to precipitate at room temperature and soluble proteins were separated using centrifugation to produce Fractions A,B,C and D (Figures 2 and 3).
Water Activity values obtained for Boarfish extracts generated using the Chemical Shift method Water Activity a w
0.5 0.45 0.4 0.35
0.328
0.3 0.25 0.2 0.158 0.15 0.1 0.055
0.04133
0.05
Fish proteins are extracted from fish using chemical and enzymatic methods. Protein hydrolysates obtained from these processes are used in the food industry as milk replacers, protein supplements, stabilisers in beverages and as flavour enhancers.2 These hydrolysates may also be a rich source of bioactive peptides or cryptides.
0 Minced and freeze dried Boarfish soluble proteins Boarfish
Boarfish bone powder
Boarfish Lipid-rich protein pellet
Figure 6: Water activity (aw) values for Boarfish protein extracts generated using the chemical shift method.
Bioactive peptides, also known as cryptides, are sequences of between two and twenty amino acids in length. They can be generated by acid/base hydrolysis, enzymatic hydrolysis, fermentation using lactic acid bacteria (LAB) or proteolytic bacteria and food processing techniques such as high pressure and temperature. They exert a positive health benefit on consumer health and can be used as preventative therapy. Many different bioactive peptides exist that can inhibit enzymes such as Angiotensin-I-converting enzyme (ACE-I), renin, and Platelet Activating Factor Acetylhydrolase (PAF-AH) that are important in heart health. These enzymes play an important role in the control of blood regulation and salt water balance within the Renin-Angiotensin Aldosterone system (RAAS) (Figure 2) and atherosclerosis within the lumen of the cell.
Water activity values obtained were all within the accepted threshold for protein powders. Amino acid analysis of protein samples Enzymatic proteolysis of Boarfish soluble protein and subsequent fractionation of the resultant BH by membrane ultrafiltration resulted in fractions rich in peptides
