María Teresa Sanz

Solubility of some phenolic compounds contained in grape seeds, in supercritical carbon dioxide

The solubility of some natural, low molecular weight phenolic compounds, 3,4-dihydroxy benzoic acid (protocatechuic acid), methyl 3,4,5-trihydroxybenzoate (gallic acid methyl ester or methyl gallate), and 3,4-dihydroxy benzaldehyde (protocatechualdehyde), in supercritical carbon dioxide (SC-CO2) has been determined at pressures from 10 to 50 MPa and temperatures from 313 to 333 K. These phenolic compounds are contained in grape seeds and other natural substrates. The data presented in this work are valuable to know the possibility of separation from their natural matrices by supercritical extraction with carbon dioxide. Data modeling has been carried out by using the Peng–Robinson equation of state (PR-EOS) to describe the behavior of the supercritical fluid (SCF) phase. Two semiempirical density dependent correlations, specifically, the Chrastil model, and a model that assumes a linear correlation between the enhancement factor and the density of the solvent, have also been used for data correlation.

Solubility of three hydroxycinnamic acids in supercritical carbon dioxide

The solubility of three trans-hydroxycinnamic acids, 4-hydroxycinnamic acid (p-coumaric acid), 3,4-dihydroxycinnamic acid (caffeic acid), and 4-hydroxy-3-methoxycinnamic acid (ferulic acid), in supercritical carbon dioxide (SC-CO2) has been determined at different pressures up to 50 MPa and temperatures from 313 to 333 K. These hydroxycinnamic acids are phenolic compounds contained in grape seeds and other natural substrates, and the data presented in this work are valuable to know the possibility of their separation from such natural matrices by extraction with SC-CO2. Experimental data have been modeled by using the Peng–Robinson equation of state (PR-EOS) to determine the fugacities of the fluid phase. Two semiempirical density dependent correlations have also been used for data correlation, specifically, the Chrastil model, and a model that assumes a linear correlation between the enhancement factor and the density of the solvent.

Formulation and characterisation of wheat bran oil-in-water nanoemulsions

Wheat bran oil (WBO) has been reported to have an important content of bioactive compounds, such as tocopherols, alkylresorcinols, steryl ferulates and other phenolic compounds; however, its poor solubility in water systems restricts its applications in the food industry. This study is focussed on the formulation of oil-in-water (O/W) nanoemulsions of WBO in order to improve the bioaccessibility of its active compounds. The influences of oil concentration, surfactant type and concentration, and emulsification method, on the droplet size and stability of the nanoemulsions were investigated. Response surface methodology was used to optimise the conditions for preparing stable nanoemulsions with the minimum droplet size. The optimal nanoemulsion was obtained when 1% of WBO and 7.3% of a surfactant mixture of Span 80 (37.4%) and Tween 80 (62.6%) were emulsified in water by high intensity ultrasonication for 50s after pre-emulsification with a high speed blender during 5 min. The optimal nanoemulsion showed good stability over time and antioxidant and tyrosinase inhibitory activities, which make it suitable for use in food applications.

Production and concentration of monoacylglycerols rich in omega-3 polyunsaturated fatty acids by enzymatic glycerolysis and molecular distillation

Production of monoacylglycerols (MAGs) rich in ω-3 polyunsaturated fatty acids (n-3 PUFAs) was conducted through short path distillation (SPD) of an acylglycerol mixture (containing 67% MAGs) produced by enzymatic glycerolysis of sardine oil with glycerol. A stepwise SPD process in a UIC KDL 5 system (vacuum 10(-3)mbar, feeding flow 1.0 mL/min) was proceeded: the first distillation performed at evaporator temperature (TE) of 110 °C to remove glycerol completely and most of FFAs; and the second distillation at optimized TE 155 °C; resulting in a stream distillate with 91% purity and 94% overall recovery of MAGs. This work also demonstrated that SPD is able to concentrate n-3 PUFAs in MAG form by distilling at proper TE e.g. 125 °C, where n-3 PUFAs are concentrated in the residues. Moreover, this work mapped out a complete processing diagram for scalable production of n-3 PUFAs enriched MAGs as potential food emulsifier and ingredient.

Kinetic study and kinetic parameters of lipase-catalyzed glycerolysis of sardine oil in a homogeneous medium

The production of polyunsaturated fatty acids (PUFAs) concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic catalysts. The enzymatic glycerolysis of sardine oil by Lipozyme® 435 to get PUFA concentrates in the forms of di- and monoacylglycerols (DAGs, MAGs) in an optimized amount of tert-butanol as the organic solvent was studied. First, mass transfer limitation of the reaction system was analyzed. The effects of different operating variables such as lipase loading, temperature and feed composition were investigated. A semi-empirical kinetic model based on the reversible elementary reactions of glycerolysis and hydrolysis of the glycerides was employed to correlate the experimental kinetic data. A molar ratio glycerol:oil of 3:1 was the optimum, which produced more than 84 wt% of MAG at 323 K. A comparison with other glycerolysis systems was performed using MAG yield, reaction rate and significance of kinetic parameters.

Kinetic Study for the Ethanolysis of Fish Oil Catalyzed by Lipozyme® 435 in Different Reaction Media

The ethanolysis of fish oil in various reaction medium (tert-pentanol, n-hexane and solvent free system) catalyzed by the immobilized commercial lipase Lipozyme(®) 435 (Candida Antarctica) at atmospheric pressure has been studied in this work. The effect of some kinetic parameters, such as the amount of lipase, temperature and the initial reactant molar ratio ethanol:oil on monoacyglyceride and ethyl ester yield has been analyzed. Experimental data were successfully correlated by a simple kinetic model based on the elementary reactions proposed in this work. At high initial reactant molar ratio the three elementary steps can be considered as irreversible. However the reaction rate constants ratio for the deacylation of monoglyceride to glycerol decreased by decreasing the molar ratio ethanol:oil. The reaction rates are slower in n-hexane as reaction medium compared to tert-pentanol and a solvent-free system, at the experimental conditions essayed in this work. In this last case, ethanol acts as solvent for reaction and as reactant.

Substrates emulsification process to improve lipase-catalyzed sardine oil glycerolysis in different systems. Evaluation of lipid oxidation of the reaction products

Mono- and diacylglycerols rich in omega-3 have a great interest due to their good bioavailability and oxidation stability compared with other kind of omega-3 concentrates. The main drawback in mono- and diacylglycerols production by glycerolysis is the immiscibility of the substrates, oil and glycerol. To improve mass transfer rates, avoiding the use of organic solvents, emulsification of both reactants as reverse micelles (glycerol-in-oil) was carried out previous to lipase-catalyzed sardine oil glycerolysis. Substrate emulsification yielded higher reaction rates compared to kinetics with no previous emulsification, but still lower than in organic solvents. To avoid the use of organic solvent, SC-CO2 was used as reaction medium but no kinetic advantages were demonstrated in the pressure range from 15 to 25 MPa. By increasing temperature, from 40 to 90°C, reaction rates increased both in a solvent-free system and in SC-CO2 medium. It was also found that an increase in temperature does not lead to an increase in the final oxidation status of the reaction products. This behavior was due to the adsorption capacity of the Lipozyme 435 support, giving lower oxidation status at the highest temperature, 80-90°C.

Omega-3 encapsulation by PGSS-drying and conventional drying methods. Particle characterization and oxidative stability.

Particles from Gas-Saturated Solutions (PGSS)-drying has been used as a green alternative to encapsulate omega-3 polyunsaturated fatty acids (n-3 PUFAs) at mild, non-oxidative conditions. PGSS-dried particles have been compared to those obtained by conventional drying methods such as spray-drying and freeze-drying, finding encapsulation efficiencies (EE) up to 98% and spherical morphology for PGSS- and spray-dried particles. Freeze-dried powders showed irregular morphology and EE from 95.8 to 98.6%, depending on the freezing method. Differential scanning calorimetry (DSC) analysis revealed glass-transition and melting peaks of OSA-starch and a cold-crystallization peak corresponding to the encapsulated n-3 PUFA concentrate. Compared to conventionally dried powders, PGSS-dried microparticles showed lower primary and secondary oxidation after 28 days of storage at 4 °C. Ascorbic acid addition combined with the mild processing conditions of PGSS-drying yielded particles with a maximum peroxide value of 2.5 meq O2/kg oil after 28 days of storage at 4 °C.