Development of a Ready-to-Eat Fish Product Enriched with Fish Oil Entrapped in a κ-Carrageenan Egg White Fish Protein Hydrolysate Dry Powder.

This work describes the development of a ready-to-eat (RTE) product based on an equal mixture of fish mince from three undervalued fish species with different fat contents and protein gelling capacity, which was enriched with fish oil entrapped in a κ-carrageenan egg white fish protein hydrolysate powder, obtained by either spray drying (SD) or heat drying (HD) at 80 °C (HD80). Previously, the spray-dried (SD) powder and heat-dried powders obtained at 45 °C, 60 °C and 80 °C (HD45, HD60 and HD80) were characterised in terms of water solubility, lipid oxidation (TBARS), hygroscopicity and ζ potential. All HD powders showed higher hygroscopicity and lower TBARS than the SD powder. The dry powder was incorporated into a blend composed of salt-ground batter and raw mince to improve binding and textural properties. Changes in water-holding capacity, colour, shear strength and microorganisms were monitored during the processing steps. The RTE product presented a high protein content and a noticeable amount of long-chain ω-3 fatty acids. The use of undervalued fish species together with fish oil and a protein hydrolysate from fish waste contribute to improving the sustainability of fishery resources, being conducive to obtaining a potentially functional RTE product.

Yogurt Fortification by the Addition of Microencapsulated Stripped Weakfish (Cynoscion guatucupa) Protein Hydrolysate.

The aim of the present work was to fortify yogurt by adding a stripped weakfish (Cynoscion guatucupa) protein hydrolysate obtained with the enzyme Protamex and microencapsulated by spray drying, using maltodextrin (MD) as wall material. The effects on the physicochemical properties, syneresis, texture, viscoelasticity, antioxidant and ACE inhibitory activities of yogurt after 1 and 7 days of storage were evaluated. In addition, microbiological and sensory analyses were performed. Four yogurt formulations were prepared: control yogurt (without additives, YC), yogurt with MD (2.1%, YMD), with the free hydrolysate (1.4%, YH) and the microencapsulated hydrolysate (3.5%, YHEn). Yogurts to which free and microencapsulated hydrolysates were added presented similar characteristics, such as a slight reduction in pH and increased acidity, with a greater tendency to present a yellow color compared with the control yogurt. Moreover, they showed less syneresis, the lowest value being that of YHEn, which also showed a slight increase in cohesiveness and greater rheological stability after one week of storage. All yogurts showed high counts of the microorganisms used as starters. The hydrolysate presence in both forms resulted in yogurts with antioxidant activity and potent ACE-inhibitory activity, which were maintained after 7 days of storage. The incorporation of the hydrolysate in the microencapsulated form presented greater advantages than the direct incorporation, since encapsulation masked the fishy flavor of the hydrolysate, resulting in stable and sensorily acceptable yogurts with antioxidant and ACE inhibitory activities.

The effect of the combined use of high pressure treatment and antimicrobial edible film on the quality of salmon carpaccio.

Fish carpaccio is a ready-to-eat product with a very limited shelf life. In the present work, the use of high pressure treatment (HP) and/or antimicrobial edible film was studied in order to improve quality and stability of salmon carpaccio. In a preliminary part of the work, a film composed of gelatin plus chitosan incorporating clove essential oil was selected, based on its physicochemical and antimicrobial properties. Eugenol and ß-caryophyllene, the main volatile components of the film, migrated to salmon muscle, the release being favored by HP and storage time. Concurrently, reducing power of the muscle increased, resulting in prevention of lipid oxidation derived from either HP or refrigerated storage. HP treatment reduced total microbial counts by 1.5 log cycles from the onset of storage, whereas the film reduced it by 2 log cycles after 3 days. The combination of HP and edible film exerted the most intense antimicrobial effect, total bacterial counts, luminescent bacteria, H2S-producing organisms, pseudomonads, enterobacteria, and lactic acid bacteria remaining constant or under detection limit over the whole storage period (11 days). The combined use of HP treatment and gelatin-chitosan-clove essential oil film is an effective way of improving quality and stability of salmon carpaccio.

Active nanocomposite films based on soy proteins-montmorillonite- clove essential oil for the preservation of refrigerated bluefin tuna (Thunnus thynnus) fillets.

This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging.

Incorporation of liposomes containing squid tunic ACE-inhibitory peptides into fish gelatin.

BACKGROUND: Hydrolysates from collagen of jumbo squid (Dosidicus gigas) tunics have shown excellent angiotensin I-converting enzyme (ACE)-inhibitory activity. However, peptides directly included in food systems may suffer a decrease in activity, which could be minimized by loading them into nanoliposomes. RESULTS: A fraction of peptides with molecular weights <1 kDa obtained from hydrolyzed squid tunics, with reasonably high ACE-inhibitory activity (half-maximal inhibitory concentration IC50 = 0.096 g L(-1)), was encapsulated in phosphatidylcholine nanoliposomes. The peptide concentration affected the encapsulation efficiency and the stability of the resulting liposomes, which remained with a high zeta potential value (-54.3 mV) for at least 1 week at the most suitable peptide concentration. The optimal peptide concentration was established as 1.75 g L(-1). Liposomes obtained with this peptide concentration showed an encapsulation efficiency of 53%, a zeta potential of -59 mV, an average diameter of 70.3 nm and proved to be stable in the pH range 3-7 at 4 °C. CONCLUSION: Liposomes containing ACE-inhibitory peptides were incorporated in fish gelatin without detriment to the rheological properties and thermal stability of the resulting cold-induced gel. The ACE-inhibitory activity of the peptide fraction, which was not affected by the encapsulation process, conferred the bioactive potential to the nanoliposome-containing gelatin gel.