Effect of enzymatic degraded polysaccharides from Enteromorpha prolifera on the physical and oxidative stability of fish oil-in-water emulsions.

To explore the potential application of enzymatic degraded polysaccharides from Enteromorpha prolifra (EEP) as antioxidant in fish oils, a stable fish oil emulsion system incorporating EEP was established. Effects of emulsifier (Tween 80, gum arabic and lecithin) and EEP concentration on the physical characteristics of fish oil emulsions were investigated. The results indicated that Tween 80 was the best choice, and 1% (w/w) of EEP was the optimum concentration for the preparation of fish oil emulsions. Influence of EEP on the oxidative stability and physical stability of fish oil emulsions was compared with that of antioxidants VE and TBHQ by determining the physical properties, lipid hydroperoxide formation, secondary reaction products formation, pH and long chain polyunsaturated fatty acid content, during storage at 45 °C. The results indicated that the fish oil emulsion system (5% oil, 1% EEP and 1% Tween 80, w/w) possessed good physical and oxidative stabilities.

Preparation, antioxidant and antimicrobial evaluation of hydroxamated degraded polysaccharides from Enteromorpha prolifera.

In order to improve the antioxidant and antimicrobial abilities, hydroxamated degraded polysaccharides from Enteromorpha prolifera (HCDPE) were prepared from the corresponding carboxymethylated degraded polysaccharides (CDPE). HCDPE was characterized by FT-IR. The weight-average molecular weight of HCDPE was determined as 55.4kDa. The in vitro antioxidant activity of HCDPE was evaluated by determining the radical (1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals) scavenging abilities and total antioxidant activity. It was found that DPPH radical scavenging ability and total antioxidant activity of HCDPE were significantly improved compared to those of CDPE. The inhibitory effects of polysaccharides against the five bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella spp.) were also evaluated by bacterial inhibition zone and minimum inhibitory concentration (MIC) assays. The results indicated that CDPE and HCDPE possess marked antimicrobial ability, while such an effect was not observed for the crude polysaccharides (PE) and the degraded polysaccharides (DPE).

Carboxymethylated degraded polysaccharides from Enteromorpha prolifera: Preparation and in vitro antioxidant activity.

In order to improve the bioactivities of the polysaccharide from Enteromorpha prolifera (PE), crude PE (Mw 1400kDa) was degraded to low molecular weight polysaccharide (44kDa) in the presence of hydrogen peroxide/ascorbic acid, followed by carboxymethylation. The reaction conditions for carboxymethylation of degraded polysaccharide (DPE) were optimized by Response Surface Methodology. The carboxymethyled degraded polysaccharide (CDPE) obtained under optimized conditions, with a degree of carboxymethylation of 0.849, was characterized by FT-IR and (13)C NMR. The molecular weight of CDPE was measured to be 53.7kDa. CDPE was evaluated for its antioxidant activity by determining the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals, and by determining the ferric reducing power. The antioxidant activity of CDPE was found to be greatly improved in comparison with degraded polysaccharide (DPE) and crude polysaccharide from Enteromorpha prolifera (PE).