Production of Protein Hydrolysate Containing Antioxidant and Angiotensin -I-Converting Enzyme (ACE) Inhibitory Activities from Tuna (Katsuwonus pelamis) Blood

Natthaphon Mongkonkamthorn,Suthasinee Yarnpakdee,Yuwares Malila,Joe M Regenstein,Sutee Wangtueai,Sakunkhun Makkhun

doi:10.3390/pr8111518

Abstract

Tuna blood (TB) was subjected to enzymatic hydrolysis. The effects of the relationship of hydrolysis time (30–180 min) and enzyme concentration (0.5–3.0% w/w protein) on the degree of hydrolysis (DH), yield, antioxidant and angiotensin-I-converting enzyme (ACE) inhibitory activities were determined. The response surface methodology (RSM) showed that TB hydrolysis’s optimum conditions were hydrolysis for 180 min and Alcalase, Neutrase or Flavourzyme at 2.81%, 2.89% or 2.87% w/w protein, respectively. The hydrolysates with good DH (40–46%), yield (3.5–4.6%), the IC50 of DPPH (0.8–1.6 mg/mL) and ABTS (1.0–1.4 mg/mL) radical scavenging activity, ferric reducing antioxidant power (FRAP) value (0.28–0.65 mmol FeSO4/g) and IC50 of ACE inhibitory activity (0.15–0.28 mg/mL) were obtained with those conditions. The TB hydrolysate using Neutrase (TBHN) was selected for characterization in terms of amino acid composition, peptide fractions and sensory properties. The essential, hydrophobic and hydrophilic amino acids in TBHN were ~40%, 60% and 20% of total amino acids, respectively. The fraction of molecular weight <1 kDa showed the highest antioxidant and ACE inhibitory activities. Fishiness and bitterness were the main sensory properties of TBHN. Fortification of TBHN in mango jelly at ≤ 0.5% (w/w) was accepted by consumers as like moderately to like slightly, while mango jelly showed strong antioxidant and ACE inhibitory activities. TBHN could be developed for natural antioxidants and antihypertensive peptides in food and functional products.

Highlights

Tuna canning is a major fish processing industry
The 2 kg of Tuna blood (TB) was packed into a polyethylene plastic bag, kept in ice with the TB to ice ratio at 1:2 (w/w) and transported to the laboratory of the College of Maritime Studies and Management, Chiang Mai University, Samut Sakhon within 30 min
Alcalase and Neutrase are endopeptidases capable of hydrolyzing proteins with broad specificity for peptide bonds and preference for the uncharged residue, whereas Flavourzyme is a mixture of endo- and exopeptidase, which can produce both free amino acids and peptides [13,22,23]

Summary

Introduction

Tuna canning is a major fish processing industry. Over 75% of tuna captured in the world are supplied for canned tuna production with commercial species such as skipjack (Katsuwonus pelamis), albacore (Thunnus alalonga), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) [1]. Processes 2020, 8, 1518 tuna processing leaves >60% byproducts such as 20–30% head, bones and gill, 10–13% dark meat, 7–12% blood and 5–7% viscera. Fresh tuna blood (TB) from bleeding and/or heading are normally released into the wastewater treatment system [2]. A large amount of blood is generated by the tuna canning industry. The utilization of TB could enhance the economic value and environmental sustainability. TB has ~5–6% crude protein [3] that might be recovered and used as a highly valued product. The utilization of animal blood for bioactive hydrolysates has been reported for chicken blood hydrolysate [4,5], pig hemoglobin and blood hydrolysates [6,7] and for deer, sheep, pig and cattle red blood hydrolysate [8]

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Conclusion