The development of tilapia fish skin gelatin nanoparticles in encapsulated biopeptides for yoghurt application

Abstract

Considerable attention has been directed to nanoparticles based on gelatin biopolymer due to its numerous available active group sites for attaching target molecules and acting as a drug or nutraceutical delivery system. The main aim using such nanoparticles is to improve the therapeutic effects and also to reduce the side effects of formulated drugs due the natural and cheap availability of gelatin. Gelatin obtained from fish skin and scales can provide a potential alternative source with almost the same rheological properties as mammalian gelatin and is a beneficial way to use fish waste such as skin, bones and fin which is generally discarded. Nanoencapsulation of bioactive compounds within fish skin gelatin nanoparticles can improve the bioavailability, delivery properties, and solubility of the nutraceutical within the blood stream. Many of such bioactive peptides (biopeptides) are potent antioxidants and as oxidative stress is the main cause of the onset of various chronic diseases encapsulation of antioxidant biopeptides within a fish gelatin nanocarrier system could be a potential remedy to prevent or delay the onset of such diseases and for better health prospects. The purpose of this study was to prepare a safe and cost efficient novel food delivery nanoparticle system encapsulating a desirable antioxidant biopeptide. A high quality protein isolate was chosen from four species; sunflower corn, palm kernel cake and moringa oriefera by alkaline extraction and isoelectric precipitation, and sunflower protein isolate (0.322±0.82 mg/ml protein content) was used as starting material for the generation of an extensive enzymatic protein hydrolysates using sequentially an endo-protease (Alcalase) and an exo-protease (Flavourzyme) and the protein hydrolysates, (biopeptide) with a degree of hydrolysis of 53.6 %, was white and non bitter. The antioxidant activity of the sunflower protein hydrolysates (biopeptide) was quite high at DPPH of 89±1.01% and FRAP assay of 968±0.68 µm/L. Gelatin was extracted from Tilapia fish at an average yield of 10% wt/wt of fish skin and scales. The proximal composition of the gelatin was similar to that of the commercial gelatins, with slightly higher moisture content. The tilapia skin gelatin had whitish yellow color and a similar pH to commercially available gelatin. Gelatin nanoparticles were prepared by a two step desolvation process encapsulating the sunflower protein hydrolysates (biopeptide) and the average diameter of the biopeptide loaded gelatin nanoparticle is between 228.3±0.11 and 1305±0.6 nm. Protein loading efficiency is 76±1.1 % at an optimal pH of 2, glutaraldehyde concentration of 2 ml and biopeptide concentration of 0.1 mg/ml and exhibits DPPH at 92% and FRAP assay of 978±0.65 µm/L. To understand the absorption and protein release of the GNPs, the biopeptide loaded gelatin nanoparticles were subjected to simulated gastrointestinal conditions mimicking the human stomach and intestine and showed a peptide release of 0.1464 and 0.277 mg/mL upon pepsin and pancreatin digestion respectively. This system also demonstrates the capability of preventing the denaturation of protein encapsulated in the GNPs. Cell adhesion studies with human fibroblasts have shown that gelatin nanoparticles do not affect the number of cells adhered to glass as compared to control cells with no particles. Standard cell viability assay demonstrated that cells incubated with gelatin nanoparticles remained more than 100% viable at concentration of 25µg/ml. Upon addition of GNPs loaded with antioxidant biopeptide to frozen yoghurt, negligible difference was measured for pH, hardness and cohesiveness; however, syneresis and adhesiveness saw a slight variation. The antioxidant activity of yoghurt fortified with the antioxidant biopeptide showed an increase with increasing concentration of GNPs added and would deliver the desired food nanoparticle delivery system.