Juan Antonio Noriega-Rodríguez

Concentration of eicosapentaenoic acid and docosahexaenoic acid from fish oil by hydrolysis and urea complexation

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from chemically or enzymatically hydrolyzed from sardine oil were concentrated by urea complexation. The enzymatic hydrolysis was effected in aqueous emulsion using five commercial lipases from Pseudomonas, three immobilized (PS-CI, PS-CII and PS-DI) and two soluble lipases (AK-20 and PS-30). EPA and DHA were determined by gas–liquid chromatography as methyl esters. Results showed that an immobilized lipase preparation (PS-CI) produced the highest degree of hydrolysis for EPA and DHA (81.5 and 72.3% from their initial content in the oil) after 24 h. After complexation of saturated and less unsaturated free fatty acids, the highest concentration of EPA (46.2%) and DHA (40.3%) was obtained using an ethanolic solution with 20% (w/w) urea and 12% (w/w) PS-CI hydrolyzed with a 78% yield. Combination of enzymatic or chemical hydrolysis with urea complexation is a promising method to obtain highly concentrated n-3 PUFA from sardine oil.

Oil production from sardine (Sardinops sagax caerulea).

Sardine (Sardinops sagax caerulea) oil was refined and the fatty acid composition as well as the physical and the chemical quality variables were monitored. The refining of crude sardine oil was carried out in three stages: alkali-refining, clay-bleaching, and steam-deodorizing. Results show that the refining process significantly improved (p < 0.05) the chemical quality of the oil, by decreasing its peroxide value (from 10.05 to 0.81 meq/kg), p-anisidine value (from 3.67 to 1.63 mmol/kg), and free fatty acids content (from 0.21 to 0.052% as oleic acid). The oxidative stability increased from 10.39 to 17.55 h (using Rancimat at 60°C, and 7 L/h air flow). These values are within the acceptable standards for edible fish oils. No significant differences (p < 0.05) were observed in fatty acids composition. The notable improvement in the physical properties of refined sardine oil produced high quality fish oil in terms of color (golden yellow) and odor (odorless).

Optimisation of Bleaching Conditions for Soybean Oil Using Response Surface Methodology

The refining process applied to soybean oil (SBO) in order to obtain the desirable purity characteristics as edible oil, produces chemical changes by partially removing desirable components such as tocopherols. In this study, the effect of temperature (76.4-143.6°C), contact time (6.4-73.6min) and clay amount (0.16-1.84% w/w) on tocopherol content and quality of SBO were evaluated. Neutralised soybean oil was subjected to bleaching using different clay amounts (Tonsil Optimum 320 FF), stirring (250rpm), and partial vacuum (60mmHg). A response surface methodology (RSM) was used to find the parameters that produce bleached oil with minimum peroxide value (PV), maximum tocopherol retention (TOCR) and light colour. The optimal bleaching conditions for SBO were: temperature, 96°C; time, 23min; clay amount, 1.4% w/w oil. Under these conditions, a bleached soybean oil with 0.1meq/kg of PV, 91.74% of TOCR, and colour 1.53 Lovibond red value units was obtained.

Kinetics of Peroxides Degradation to Hexenal During Bleaching of High Oleic Safflower Oil

Bleaching is an important step of the vegetal oil refining for the removal of impurities. Some of the reactions that take place during this stage can be explained by the catalytic properties of bleaching clays. The most important reaction is the decomposition of peroxides to secondary oxidation products, mainly trans-2-hexenal. Therefore, in the present study, empirical and mathematical models were applied to predict the kinetic parameters of peroxide reduction and the formation of trans-2-hexenal during bleaching of high oleic safflower oil. For this, neutralized high oleic safflower oil was mixed with bleaching clay (Tonsil Optimum 320 FF) at three different concentrations (0.5%, 1.0%, and 1.5% based on the weight of the oil), in a laboratory reactor with agitation at 90 °C, 100 °C, and 110±1 °C during 60 min. Results showed that the first-order mathematical model is suitable to predict both peroxide reduction and formation of trans-2-hexenal (R2 > 0.90). Kinetics parameters of initial rate (k0) and the decontamination constant (kd) suggest a high correlation between peroxide reduction to trans-2-hexenal and clays used for bleaching high oleic safflower oil. This information may be used to design particular bleaching conditions for high oleic safflower oil.