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Garcia-Moreno P.J.,University of Granada | Batista I.,DivAv | Pires C.,DivAv | Bandarra N.M.,DivAv | And 3 more authors.
Food Research International | Year: 2014

In this study, five discarded species in the Mediterranean Sea, namely sardine, horse mackerel, axillary seabream, bogue and small-spotted catshark, were evaluated as raw material for obtaining fish protein hydrolysates exhibiting antioxidant activity. The DH of the hydrolysates ranged from 13.2 to 21.0%, with a protein content varying from 60.7 to 89.5%. The peptide profile of all hydrolysates was very similar, except for the hydrolysate of small-spotted catshark. Their lipid content was found to be between 4.6 and 25.3%. The highest DPPH scavenging activity was found for the hydrolysates of sardine and horse mackerel with EC50 values varying from 0.91 to 1.78mg protein/mL. Sardine and small-spotted catshark hydrolysates exhibited the highest ferrous chelating activity with an EC50 value of 0.32mg protein/mL. Moreover, sardine and bogue hydrolysates presented the highest reducing power. Finally, a total of six antioxidant peptides were theoretically identified within the structure of myosin and actin proteins from sardine and small-spotted catshark. The potential antioxidant activity exhibited by the hydrolysates suggests that it is feasible to obtain added-value products such as natural antioxidants from these discarded species. © 2014 Elsevier Ltd.

Garcia-Moreno P.J.,University of Granada | Morales-Medina R.,University of Granada | Perez-Galvez R.,University of Granada | Bandarra N.M.,DivAv | And 2 more authors.
International Journal of Food Science and Technology | Year: 2014

The aim of this study was to evaluate the influence of the processing conditions (pretreatment temperature: 5-55°C, pressure: 60-120 bar and number of pressing stages: 1-3) on the yield and quality (free fatty acids, peroxide value, p-anisidine and Rancimat induction period) of the oil extracted from whole sardine by hydraulic pressing. Experimental factors were investigated by a designed experiment and optimised by response surface methodology. A maximum yield of oil, 12.47%, was obtained at 55°C, 60 bar and two pressing stages. Regarding oil quality, it was found minimum values for acidity (0.25% oleic at 55°C, 60 bar and one pressing stage) and for peroxide value (0.29 meq kg-1 oil at 5°C, 60 bar and one pressing stage). Hence, the opposite effect of pretreatment temperature and number of pressing stages on the yield of oil and on its oxidation parameters suggested applying the weighted-sum method as multiobjective optimisation technique. © 2014 Institute of Food Science and Technology.

Bispo P.,New University of Lisbon | Batista I.,DivAv | Bernardino R.J.,Polytechnic Institute of Leiria | Bandarra N.M.,DivAv
Applied Biochemistry and Biotechnology | Year: 2014

The increasing evidence on the differential biochemical effects of eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) raises the need of n-3 highly unsaturated fatty acid concentrates with different amounts of these fatty acids. In the present work, physicochemical and enzymatic techniques were combined to obtain acylglycerols, mainly triacylglycerols (TAG), rich in n-3 fatty acids. Sardine oil was obtained by washing sardine (Sardina pilchardus) mince with a NaHCO3 solution, hydrolyzed in a KOH-ethanol solution, and concentrated with urea. The esterification reaction was performed in the stoichiometric proportion of substrates for re-esterification to TAG, with 10 % level of Rhizomucor miehei lipase based on the weight of substrates, without any solvent, during 48 h. This procedure led to approximately 88 % of acylglycerols, where more than 66 % were TAG and the concentration of n-3 fatty acids was higher than 60 %, the EPA and DHA ratio (EPA/DHA) was 4:1. The content of DHA in the unesterifed fraction (free fatty acids) increased from 20 to 54 %, while the EPA level in the same fraction decreased from 33 to 12.5 % (EPA/DHA ratio ≈1:4). Computational methods (density functional theory calculations) have been carried out at the B3LYP/6-31G(d,p) level to explain some of the experimental results. © 2013 Springer Science+Business Media.

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