Tilapia is a popular freshwater fish and among the important cultured fish grown worldwide. In this study, fish protein
hydrolysate was produced from tilapia (Oreochromis niloticus) by-product (TB) and tilapia muscle (TM) through enzymatic
hydrolysis using alcalase. The TB and TM protein hydrolysates were evaluated for its characteristics in terms of angiotensin
I-converting enzyme (ACE) inhibition activity, peptide size distribution, and functional properties. Hydrolysis for 1 h for
TB and TM successfully produced low molecular weight peptides (<14.2kDa) with the highest ACE inhibitory activities.
The findings also demonstrated that both samples have high nitrogen solubility (>80% at pH2-9) and good emulsifying,
water and oil holding capacities. The study indicated that tilapia protein hydrolysates have the potential to be used as
functional food products.
Fish protein hydrolysate was prepared from tilapia muscle using commercial Alcalase enzyme. Optimization of enzymatic hydrolysis process for preparing tilapia muscle protein hydrolysates (TMPH) was performed by employing central composite design (CCD) method of response surface methodology (RSM). O-phtaldialdehyde (OPA) method was employed to calculate the degree of hydrolysis (DH), which is the key parameter for monitoring the reaction of protein hydrolysis. The suggested model equation was proposed based on the effects of pH, temperature, substrate concentration and enzyme concentration on the DH. Optimum enzymatic hydrolysis conditions using Alcalase enzyme were obtained at pH7.5, temperature of 50oC, substrate concentration of 2.5% and enzyme concentration of 4.0%. Under these conditions, the highest value of the DH was achieved at 25.16% after hydrolysing at 120 min. The TMPH was further assessed for their nutritional value with respect to chemical and amino acid compositions. Molecular weight distributions of TMPH were characterized by SDS-PAGE. TMPH contains moderate amount of protein (28.14%) and good nutritive value with respect to the higher total amino acid composition (267.57 mg/g). Glutamic acid, aspartic acid and lysine were the most abundant amino acids present in TMPH with values 42.68, 29.16 and 26.21 mg/g, respectively. Protein hydrolysates from tilapia muscle containing a desirable peptide with low molecular weight which may potentially to be used as functional food products.
In the present research, microalgae protein hydrolysate of Nannochloropsis gaditana (MPH) was extracted via enzymatic hydrolysis using alcalase enzyme. Hydrolysis conditions like (pH, temperature, enzyme concentration and substrate concentration) were optimized by Response Surface Methodology (RSM) using Central Composite Design (CCD). Four range of independent variables namely; pH (7-9), temperature (45-55°C), substrate concentration (2-6 g/L) and enzyme concentration (0.2-0.4 g/L) were used to study the influence of these parameters on the degree of hydrolysis. The CCD consisted of twenty-four experimental points and six replicates of central points with the optimum conditions obtained from this experiment were at pH 8.14, a temperature 51.4°C, a substrate concentration 5.48 g/L and an enzyme concentration 0.26 g/L with maximum degree hydrolysis of 55.76%. All experiments were fixed at 24 hours reaction time. The degree of hydrolysis of MPH was analysed using O-phthaldehyde (OPA) method to quantify the cleavage of peptide bond. The optimized sample was evaluated for its antioxidant activity using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) assay with 52.19% and 2, 2'- azino-bis (ethylbenzthiazoline-6-sulfonic acid (ABTS) assay with 14.13%. The bioactive peptides contained in Nannochloropsis gaditana have the ability to scavenge free radicals and act as good antioxidants.