A lumped model of the lipase catalyzed hydrolysis of sardine oil to maximize polyunsaturated fatty acids content in acylglycerols.

The aim of this work was to produce diacylglycerols (DAG) and monoacylglycerols (MAG) with a high content of polyunsaturated fatty acids (PUFA). Rhizomucor miehei lipase mediated-hydrolysis of sardine oil was conducted at several water activities. The system was mechanistically modeled to predict the time evolution of the concentration of triacylglycerols, DAG, MAG and free fatty acids (FFA) and the concentration of saturated, mono- and polyunsaturated fatty acids. The release of the first fatty acid from the triacylglycerol was independent on the unsaturation degree. Contrary, the hydrolysis of the second one was highly affected by the degree of unsaturation, PUFA being the fatty acids that showed the highest resistance to hydrolysis. MAG percentage was maximum (7mol%) at lower water activities, while DAG content was favored at higher water activities (35mol%), achieving a 2-fold concentration of DHA.

Development of an up-grading process to produce MLM structured lipids from sardine discards.

The aim of the work was to produce MLM structured lipids with caprylic acid (M) as medium chain fatty acid located at the external bonds of the glycerol backbone and concentrated polyunsaturated fatty acids (L) from sardine discards (Sardine pilchardus) in the central bond of the glycerol. To that end, the following steps were conducted: (i) fish oil extraction, (ii) Omega-3 free fatty acids (FFA) concentration (low temperature winterization), (iii) two-steps enzymatic esterification and (iv) triacylglycerols (TAG) purification (liquid column chromatography). The resultant purified triacylglycerols accomplished with the oxidative state (peroxide and anisidine value, PV and AV) required for refined oils. As enzymatic treatment, Omega-3 concentrate FFA (Omega-3>600mg Omega-3 per g oil) were esterified with dicaprylic glycerol employing Novozyme 435. This process presented high regioselectivity, with ∼80mol% of concentrated fatty acids esterified at the sn-2 position.

Modelling of the production of ACE inhibitory hydrolysates of horse mackerel using proteases mixtures.

Fish protein hydrolysates from Mediterranean horse mackerel were produced by using a mixture of two commercial endoproteases (i.e. subtilisin and trypsin) at different levels of substrate concentration (2.5 g L(-1), 5 g L(-1), and 7.5 g L(-1) of protein), temperature (40 °C, 47.5 °C, and 55 °C) and percentage of subtilisin in the enzyme mixture (0%, 25%, 50%, 75% and 100%). A crossed mixture process model was employed to predict the degree of hydrolysis (DH) and the ACE inhibitory activity of the final hydrolysates as a function of the experimental factors. Both models were optimized for a maximum DH and ACE inhibition. A maximum DH (17.1%) was predicted at 2.54 g L(-1) of substrate concentration, 40 °C and an enzyme mixture comprising 38.3% of subtilisin and 61.7% of trypsin. Although its proteolytic activity is limited, the presence of trypsin in the enzyme mixture allowed obtaining higher degrees of hydrolysis at low temperatures, which is desirable to minimize thermal deactivation of the proteins. Similarly, a percentage of ACE inhibition above 48% was attained at 2.5 g L(-1) of protein, 40 °C and a 1 : 1 mixture of both proteases. Higher values of ACE inhibition could be attained by increasing both the temperature and the amount of trypsin in the enzyme mixture (e.g. 50% ACE inhibition at 55 °C and 81.5% of trypsin). Finally, those hydrolysates exhibiting the highest levels of ACE inhibition were subjected to simulated gastrointestinal digestion. These assays confirmed the resistance of active fractions against their degradation by digestive enzymes.

Functional and antioxidant properties of hydrolysates of sardine (S. pilchardus) and horse mackerel (T. mediterraneus) for the microencapsulation of fish oil by spray-drying.

The functionality of fish protein hydrolysates (FPH) for the microencapsulation of fish oil was investigated. Muscle protein from sardine (Sardina pilchardus) and horse mackerel (Trachurus mediterraneus) was hydrolysed using Alcalase or trypsin. Physically stable emulsions suitable for spray-drying were obtained when using FPH with a degree of hydrolysis of 5%. Microencapsulation efficiency amounted to 98±0.1% and oxidative stability of the encapsulated oil over a period of twelve weeks was in a similar range as it is reported for other matrix systems. Therefore, the suitability of FPH for use in spray-dried emulsions has been shown for the first time. Since no clear correlation between the antioxidative activity of the FPH and the course of lipid oxidation could be established future research is required to more specifically characterise the molecular structure of the peptides and its impact on protein alteration and role in lipid oxidation.

Seasonal variations in the regiodistribution of oil extracted from small-spotted catshark and bogue.

The aim of this work was to seasonally characterize the nutritional quality of oil extracted from small-spotted catshark (Scyliorhinus canicula) and bogue (Boops boops). The proximate composition, lipid profile and regiodistribution of the fatty acid in the glycerol backbone were analyzed. In addition, three nutritional indexes were calculated (atherogenicity and thrombogenicity indexes and the hypocholesterolaemic/hypercholesterolaemic ratio). Both species presented PUFA as the predominant fraction, the most abundant being DHA. Healthy values of the aforementioned indexes were maintained throughout the year. Moreover, the relative composition of omega 3 fatty acids at the sn-2 position ranged from 47.3 to 66.8 mol%, attracting interest in the employment of these oils as the raw source for the production of 2-monoacylglycerols. Regarding the individual behavior of each fatty acid, DHA presented a high tendency to occupy the sn-2 bond, whereas EPA presented the opposite behavior.