Beatriz Torrestiana-Sánchez

In seeking alternatives for reducing environmental damage, fabricating filtration membranes using biopolymers derived from agro-industrial residues, such as cellulose acetate (CA), partially dissolved with green solvents, represents an economical and sustainable option. However, dissolving CA in green solvents through mechanical agitation can take up to 48 h. An ultrasonic probe was proposed to accelerate mass transfer and polymer dissolution via pulsed interval cavitation. Additionally, ultrasound-assisted phase inversion (UAPI) on the external coagulation bath was assessed to determine its influence on the properties of flat sheet and hollow fiber membranes during phase inversion. Results indicated that the ultrasonic pulses reduced dissolution time by up to 98% without affecting viscosity (3.24 ± 0.06 Pa·s), thermal stability, or the rheological behavior of the polymeric blend. UAPI increased water permeability in flat sheet membranes by 26% while maintaining whey protein rejection above 90%. For hollow fiber membranes, UAPI (wavelength amplitude of 0 to 20%) improved permeability by 15.7% and reduced protein retention from 90% to 70%, with MWCO between 68 and 240 kDa. This report demonstrates the effectiveness of ultrasonic probes for decreasing the dissolution time of dope solution with green cosolvents and its potential to change the structure of polymeric membranes by ultrasound-assisted phase inversion.

The effect of temperature, pH, and the enzyme-to-substrate ratio (E/S) on the degree of hydrolysis (DH) of lecithin-free egg yolk (LFEY) protein was optimized by using response surface methodology (RSM). A factorial design was applied to maximize DH and the initial reaction rate (V₀). The DH values varied from 16 to 36 % and V₀ from 69 to 287 g/L h in the range of tested conditions. The pH was the variable with a major influence on DH and V₀. Under the optimized conditions (60°C, pH 9, and E/S=0.35 AU/g) most of the peptides in the hydrolysates had a molecular weight (MW) lower than 12 kDa since the first 10 min of the reaction. Hydrolysates collected after 60 min of the reaction contained mostly oligopeptides (MW<3.5 kDa) with potential antioxidant activity. These hydrolysates might be used as ingredients in high-protein nutritional supplements or the formulation of clinical nutritional products.

Lecithin-free egg yolk (LFEY) is a byproduct of the extraction of egg-yolk phospholipids, which contain approximately 46% egg yolk proteins (EYPs) and 48% lipids. The enzymatic proteolysis is the alternative to increase the commercial value of LFEY. The kinetics of proteolysis in full-fat and defatted LFEY with Alcalase 2.4 L was analyzed in terms of the Weibull and Michaelis–Menten models. A product inhibition effect was also studied in the full-fat and defatted substrate hydrolysis. The molecular weight profile of hydrolysates was analyzed by gel filtration chromatography. Results pointed out that the defatting process did not importantly affect the maximum degree of hydrolysis (DHmax) in the reaction but rather the time at which DHmax is attained. The maximum rate of hydrolysis (Vmax) and the Michaelis–Menten constant KM were higher in the hydrolysis of the defatted LFEY. The defatting process might have induced conformational changes in the EYP molecules, and this affected their interaction with the enzyme. Consequently, the enzymatic reaction mechanism of hydrolysis and the molecular weight profile of peptides were influenced by defatting. A product inhibition effect was observed when adding 1% hydrolysates containing peptides lower than 3 kDa at the beginning of the reaction with both substrates.

The two main challenges for industrial application of membrane distillation (MD) are mitigation of temperature polarization and reduction of high-energy consumption. Despite the development of advanced materials and the configuration improvements of MD units, membrane surface modification is still one of the alternatives to overcome temperature polarization and improve membrane performance. This work reports a novel and simple method to modify the physical and chemical properties of the polypropylene membrane in order to improve its performance in direct contact membrane distillation (DCMD). The membrane was grafted by polymerization with 1-hexene, UV irradiation, and benzophenone as a photoinitiator. A grafting degree of up to 41% was obtained under UV irradiation for 4 h. The performance of the modified membrane in DCMD was evaluated at different temperatures and salt concentrations in the feed. First, it was found that there was an increase of the vapor permeate flux in the MD process within the range of tested temperatures and salt concentrations. The results were analyzed in terms of the physical properties of the membrane, the transport phenomena, and the thermal efficiency of the process. Theoretical analysis of the results indicated that grafting increased the transfer coefficients of mass and heat of the membrane. Hence, it improved the membrane performance and the thermal efficiency of the DCMD process.

In this study, aqueous enzymatic extraction (AEE) was evaluated during the process of obtaining oil from mamey sapote seed (OMSS). Viscozyme L enzyme complex was used at pH 4 and 50 °C during the optimization of the extraction process by central composite design and response surface methodology. Optimal conditions were: 3.5% (w/w) of enzyme (regarding the seed weight), 5.5 h of incubation time, 235 rpm of agitation rate, and 1:3.5 of solid-to-liquid ratio. These conditions enabled us to obtain an OMSS yield of 66%. No statistically significant differences were found in the fatty acid profile and physicochemical properties, such as the acid and iodine values and the percentage of free fatty acids, between the oil obtained by AEE or by the conventional solvent extraction (SE). However, the oxidative stability of the oil obtained by AEE (11 h) was higher than that obtained by SE (9.33 h), therefore, AEE, in addition to being an environmentally friendly method, produces a superior quality oil in terms of oxidative stability. Finally, the high oil content in mamey sapote seed, and the high percentage of oleic acid (around 50% of the total fatty acid) found in this oil, make it a useful edible vegetable oil.