Pedro J. García-Moreno

Physical and oxidative stability of fish oil-in-water emulsions stabilized with fish protein hydrolysates.

The emulsifying and antioxidant properties of fish protein hydrolysates (FPH) for the physical and oxidative stabilization of 5% (by weight) fish oil-in-water emulsions were investigated. Muscle proteins from sardine (Sardina pilchardus) and small-spotted catshark (Scyliorhinus canicula) were hydrolyzed to degrees of hydrolysis (DH) of 3-4-5-6% with subtilisin. Sardine hydrolysates with low DH, 3% and 4%, presented the most effective peptides to physically stabilize emulsions with smaller droplet size. This implied more protein adsorbed at the interface to act as physical barrier against prooxidants. This fact might also be responsible for the higher oxidative stability of these emulsions, as shown by their lowest peroxide value and concentration of volatiles such as 1-penten-3-one and 1-penten-3-ol. Among the hydrolysates prepared from small-spotted catshark only the hydrolysate with DH 3% yielded a physically stable emulsion with low concentration of unsaturated aldehydes. These results show the potential of FPH as alternative protein emulsifiers for the production of oxidatively stable fish oil-in-water emulsions.

Influence of casein-phospholipid combinations as emulsifier on the physical and oxidative stability of fish oil-in-water emulsions.

The objective of this study was to investigate the influence of casein (0.3% w/w) and phospholipid (0.5% w/w) emulsifier combinations on the physical and oxidative stability of 10% fish oil-in-water emulsions at pH 7. For that purpose, three phospholipids were evaluated, namely, lecithin (LC), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). The emulsion stabilized with LC showed the best physical stability having the most negative zeta potential and the lowest mean droplet size. In addition, this emulsion was also the least oxidized in terms of peroxide value and concentration of the volatile oxidation product 1-penten-3-ol. This finding is not explained by the antioxidant activity of LC because it showed similar DPPH scavenging activity and lower metal chelating activity than the other phospholipids. Therefore, these results suggested that other factors such as the combination of casein and lecithin, which could result in a favorable structure and thickness of the interfacial layer, prevented lipid oxidation in this emulsion.

Lipid characterization and properties of protein hydrolysates obtained from discarded Mediterranean fish species

BACKGROUND Discards are an important fraction of the by-products produced by the fishing industry. As a consequence of their low commercial acceptance, it is necessary to provide added value to these underutilized materials. In this study the lipid fraction of three discarded fish species in the western Mediterranean Sea, namely sardine (Sardina pilchardus), mackerel (Scomber colias) and horse mackerel (Trachurus trachurus), was characterized and the angiotensin I-converting enzyme (ACE)-inhibitory and antioxidative activities of their protein hydrolysates were evaluated. RESULTS Processing of these biomaterials led to oils with a high content of omega-3 polyunsaturated fatty acids (PUFAs), ranging from 220.5 g kg(-1) for horse mackerel to 306.0 g kg(-1) for sardine. Regarding the protein fraction, most of the hydrolysates presented ACE inhibition values higher than 60%, corresponding to IC50 values varying from 345 µg protein mL(-1) for mackerel to 400 µg protein mL(-1) for sardine. Moreover, most of the hydrolysates exhibited acceptable antioxidative activity, namely 35-45% inhibition of 1,1-diphenyl-2-picrylhydrazyl (DPPH). CONCLUSION This study suggests that the three discarded species evaluated are valuable raw materials for the production of bioactive ingredients such as omega-3 PUFAs and protein hydrolysates exhibiting antihypertensive and antioxidative activities.

Functional, bioactive and antigenicity properties of blue whiting protein hydrolysates: effect of enzymatic treatment and degree of hydrolysis

BACKGROUND Fish discards represent an important under-utilisation of marine resources. This study evaluated the up-grading of the protein fraction of blue whiting (Micromesistius poutassou) discards by the production of fish protein hydrolysates (FPHs) exhibiting functional, antioxidant, angiotensin-I converting enzyme (ACE)-inhibitory and antigenicity properties. RESULTS FPHs with low DH (4%) showed better emulsifying, foaming and oil binding capacities, particularly those obtained using only trypsin. FPHs with DH 4% exhibited also the stronger antioxidant activity, especially the one obtained using only subtilisin (IC50 = 1.36 mg protein mL-1 ). The presence of hydrophobic residues at the C-terminal of the FPH produced using subtilisin also led to the stronger ACE-inhibitory activity. However, FPHs with high DH (12%), which implies a higher proportion of short peptides, was required to enhance ACE-inhibition (IC50 = 172 µg protein mL-1 ). The antigenic levels of the FPH were also reduced with DH independently of the enzymatic treatment. Nevertheless, the highest degradation of fish allergens (e.g. parvalbumin) was also obtained when using only subtilisin. CONCLUSION These results suggest that added-value products for food applications can be produced from the protein fraction of discards.

Physical and oxidative stability of fish oil-in-water emulsions fortified with enzymatic hydrolysates from common carp (Cyprinus carpio) roe

Physical and oxidative stability of 5% (by weight) cod liver oil-in-water emulsions fortified with common carp (C. carpio) roe protein hydrolysate (CRPH) were examined. CRPH was obtained by enzymatic hydrolysis of discarded roe by using Alcalase 2.4L for 30, 60, 90, and 120min to yield different degrees of hydrolysis (DH). All the hydrolysates showed in vitro antioxidant activity in terms of radical scavenging and chelating properties. CRPH-containing emulsions had significantly smaller droplets than control (p<0.05). Besides, CRPH rendered rheological stability to the emulsions. It also prevented the loss of tocopherol and polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). CRPH retarded primary and secondary oxidation in emulsions as evidenced by peroxide values (PVs) and secondary volatile oxidation products, respectively. All the mentioned effects were compared among CRPHs with varying DH (7.6-10.2%). However, CRPH-containing emulsions had high levels of 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-butanone after storage.

Use of Electrohydrodynamic Processing for Encapsulation of Sensitive Bioactive Compounds and Applications in Food

The use of vitamins, polyphenolic antioxidants, omega-3 polyunsaturated fatty acids (PUFAs), and probiotics for the fortification of foods is increasing. However, these bioactive compounds have low stability and need to be protected to avoid deterioration in the food system itself or in the gastrointestinal tract. For that purpose, efficient encapsulation of the compounds may be required. Spray drying is one of the most commonly used encapsulation techniques in the food industry, but it uses high temperature, which can lead to decomposition of the bioactive compounds. Recently, alternative technologies such as electrospraying and electrospinning have received increasing attention. This review presents the principles of electrohydrodynamic processes for the production of nano-microstructures (NMSs) containing bioactive compounds. It provides an overview of the current use of this technology for encapsulation of bioactive compounds and discusses the future potential of the technology. Finally, the review discusses advanced microscopy techniques to study the morphology of NMSs.

Combination of sodium caseinate and succinylated alginate improved stability of high fat fish oil-in-water emulsions

Sodium caseinate (CAS) and commercial sodium alginate (CA), long chain modified alginate (LCMA) or short chain modified alginate (SCMA) were used in combination for emulsifying and stabilizing high fat (50-70%) fish oil-in-water emulsions. Physical (creaming, droplet size, viscosity and protein determination) and oxidative (primary and secondary oxidation products) stabilities of the emulsions were studied during 12 days of storage. Creaming stability was higher for emulsions produced with alginates and CAS compared to emulsions prepared with only CAS. Combined use of CAS + LCMA performed better in terms of physical stability compared to emulsions produced with only CAS. However, the oxidative stability of this emulsion was inferior probably due to the presence of an unsaturated carbon chain in LCMA structure. CAS + SCMA emulsions not only showed better physical stability such as smaller droplet size, lower creaming and higher viscosity, but also had an improved oxidative stability than emulsions produced with only CAS.

Physical and oxidative stability of high fat fish oil-in-water emulsions stabilized with sodium caseinate and phosphatidylcholine as emulsifiers

The physical and oxidative stability of high-fat omega-3 delivery systems such as fish oil-in-water emulsions stabilized with combinations of sodium caseinate (CAS) and phosphatidylcholine (PC) was optimized. The influence of fish oil content (50, 60 and 70%, w/w), amount of total emulsifier CAS + PC (1.4, 2.1 and 2.8%, w/w) and ratio between CAS and PC (0.4, 1.2 and 2) on physical and oxidative parameters was investigated. Creaming and droplet size significantly decreased when the amount of fish oil, total emulsifier and ratio of CAS to PC were increased. Viscosity decreased significantly with decreasing fish oil content, whereas the ratio of CAS to PC did not have a significant influence. Decreasing the ratio of CAS to PC led to emulsions with a significantly lower concentration of 1-penten-3-ol, while no significant effect was found for other volatiles such as (E)-2-pentenal, (E)-2-hexenal and (E,E)-2,4-heptadienal.

Biopolymers for the Nano-microencapsulation of Bioactive Ingredients by Electrohydrodynamic Processing

Electrohydrodynamic processing, including electrospinning and electrospraying, is an emerging technique for the encapsulation of bioactive ingredients (e.g. omega-3, vitamins, antioxidants, probiotics) with interest for the functional food industry. This chapter presents the fundamentals of electrohydrodynamic processes for the production of nano-microstructures (fibers or capsules) loaded with bioactive compounds. Particularly, it focuses on the properties as well as electrospinning and electrospray processing of food-grade polymers. The physicochemical characteristics of the resulting nano-microencapsulates will also be discussed. Electrospun and electrospray food-grade polymers include biopolymers such as proteins (e.g. zein, gelatin, whey, casein, amaranth, soy, egg and fish protein) and polysaccharides (e.g. pullulan, dextran, chitosan, starch, alginate, cellulose, cyclodextrin, xanthan gum), as well as blends of biopolymers with biocompatible synthetic polymers (e.g. poly-vinyl alcohol).

Fish Discards as Source of Health-Promoting Biopeptides

Abstract The vast diversity of marine organisms is a source of enormous potential for obtaining bioactive compounds for use in the food industry. In this context, discards, which are defined as the fraction of the fish catch that is not retained onboard but rejected to the sea due to commercial standards, fishing regulations, or them being nontarget species, are regarded as a waste of resources and an environmental problem. The new EU Common Fisheries Policy introduced a discard ban for pelagic species on January 1, 2015. The composition of discarded materials (1%–18% lipids and 15%–20% proteins) means that they are receiving increased attention for their use in biotechnological applications. The six species studied in this chapter, namely, the axillary seabream ( Pagellus acarne ), small-spotted catshark ( Scyliorhinus canicula ), sardine ( Sardina pilchardus ), horse mackerel ( Trachurus mediterraneus ), bogue ( Boops boops ), and blue whiting ( Micromesistius poutassou ), represent more than 85% of the total discards in the Alboran Sea. This chapter mainly focuses on upgrading the protein fraction of the aforementioned species into biopeptides. To this end, compacting and separation stages were designed to obtain the lipid and protein fractions. The influence of enzymatic hydrolysis on the antihypertensive, antioxidant, anticholesterolemic, and antimicrobial activities of the proteins was also analyzed. In addition, the bioavailability of the biopeptides was analyzed using simulated gastrointestinal digestion. Finally, the methods employed for the characterizing and identification of the active peptides are also described. These biopeptides can be employed in the formulation of functional food.