Papers by Alejandro Rocha Uribe
Folia Microbiologica, Jan 6, 2023
We present the application of a methodology for process intensification (PI) to generate and iden... more We present the application of a methodology for process intensification (PI) to generate and identify an improved option for the enzymatic production of biodiesel, whose industrial-scale implementation has not been realized, mainly due to the high cost of the enzyme compared to alkaline catalyst. The problem of synthesis / design is mathematically defined as an optimization problem MINLP (Mixed integer nonlinear problem) whose complexity is increased by the inclusion of a superstructure to generate all the possible options, and hence unsolvable. Therefore, we propose a method of dividing the whole problem into sub-problems. This strategy is included in the PI method, wherein, starting from a base case analysis, limitations are identified and based on them, intensified options are generated. These generated options are evaluated using logical, structural and operational constraints and a generic model represented by a superstructure which includes all the options. The design methodology provided an option for enhanced enzymatic production of biodiesel. With this, the implementation the enzymatic route for biodiesel at commercial scale can be accelerated.
Energies
This work aimed to evaluate the ability of lipase extract powder obtained from Leonotis nepetifol... more This work aimed to evaluate the ability of lipase extract powder obtained from Leonotis nepetifolia seed for enzyme-catalyzed biodiesel production using Leonotis nepetifolia oil, commercial olive oil, and waste cooking oil as substrates. The lipase extract powder showed an enzymatic activity and hydrolysis percentage of 24.7 U/g and 21.31%, respectively, using commercial olive oil as a reference. Transesterification reaction conditions were 40 g of substrate, 34 °C, molar ratio oil: methanol of 1:3, lipase extract powder 20 wt%, phosphates buffer (pH 4.8) 20 wt%, and a reaction time of 8 h. Transesterification yields of 74.5%, 71.5%, and 69.3% for commercial olive oil, waste cooking oil, and Leonotis nepetifolia oil were obtained, respectively. Biodiesel physicochemical parameters were analyzed and compared with the international standards: EN 14214 (European Union) and ASTM D6751 (American Society for Testing and Materials). The biodiesel’s moisture and volatile matter percentages,...
Journal of the American Oil Chemists' Society, 2008
Specific structured lipids (SSL), previously produced by enzymatic acidolysis of coconut oil with... more Specific structured lipids (SSL), previously produced by enzymatic acidolysis of coconut oil with different levels of conjugated linoleic acid (CLA) as fatty acid (FA), using a sn-1, 3 specific immobilized lipase, were used to prepare randomized structured lipids (RSL). A fraction of each SSL was subjected to chemical interesterification with sodium methoxide catalyst in order to modify the FA positional distribution and produce the corresponding RSL. Both families of structured lipids (SL) containing CLA were physicochemically characterized. Then, analysis of variance (ANOVA) was performed to evaluate the effects of CLA content (10, 20, 30 and 40%) and FA positional distribution (specific and randomized) on physicochemical properties of SL. Free fatty acids (FFA), peroxide value (PV) and p-anisidine value (p-AV) were not significantly affected by either CLA content or distribution. As expected, the iodine value (IV) and saponification value (SV) were influenced by CLA content but not by FA positional distribution, while oxidative stability index (OSI) was affected by both factors. Dropping point (DP), cloud point (CP) and solid fat content (SFC) decreased with the increase of CLA, while viscosity increased with the level of CLA. The FA positional distribution affected practically all the evaluated physical properties of SL, except CP and DP.
Food Chemistry, 2007
... as an essential oil, which has proven as a good antimicrobial and antioxidant ... Solubility ... more ... as an essential oil, which has proven as a good antimicrobial and antioxidant ... Solubility problems,chemical constituents, and their hydrophiliclipophilic distribution are key factors that ... N. Andarwulan, D. Fardiaz, GA Wattimena and K. Shetty, Antioxidant activity associated with ...
Quimica Hoy
En este trabajo se evaluó la recuperación de grasas de una empresa pasteurizadora de leche para s... more En este trabajo se evaluó la recuperación de grasas de una empresa pasteurizadora de leche para su uso en la producción de biodiesel con la finalidad de aprovechar los residuos lácteos y reducir los problemas relacionados con la generación de biosólidos en la planta de tratamiento de aguas residuales (PTAR) de dicha empresa. La producción de biodiesel se realizó por transesterificación en fase homogénea y heterogénea utilizando como materia prima los residuos grasos. Para los dos procesos, se evaluó el rendimiento de producción de biodiesel y la calidad del biodiesel de acuerdo a la norma europea EN 14214. La reacción en fase homogénea se realizó empleando metanol y grasa residual en una proporción molar de 6:1 (metanol:grasa), NaOH como catalizador al 0.8 % p/p con respecto a la masa de la grasa, temperatura de 60 °C y un tiempo de reacción de 60 minutos. Para la reacción en fase heterogénea, se utilizó un hidróxido doble laminar (HDL) como catalizador heterogéneo al 3.5 %p/p, una ...
Phyton
The need for renewable energy sources makes microalgae an essential feedstock for biofuels produc... more The need for renewable energy sources makes microalgae an essential feedstock for biofuels production. The molecular aspects and the response to nitrogen (N)-limited conditions with a phytohormone stimulus in microalgae have been slightly explored. In this work, Scenedesmus obliquus was used as a study model to analyze the effect of benzyl amino purine (BAP) and gibberellic acid (GA) coupled to nitrogen limitation on cell growth, biomass and fatty acids. The selected 10-5 M BAP increased the biomass by 1.44-fold, and 10-6 M GA by 1.35-fold. The total lipids also increased by 2.8 and 1.11-fold, respectively. The 10-5 M BAP and 10-6 M GA addition to S. obliquus cultures at different initial nitrogen percentages (N-0, N-25, and N-50) showed a significant increase in cell growth and biomass productivity compared to the unstimulated cultures. BAP N-0 and GA N-0 produced the highest lipid yields with 55% and 50%, respectively. The lipid profile analysis revealed an increase, particularly in C18:1 and C16:0 fatty acids. Gene expression analysis showed an over-expression of acyl carrying protein (ACP), stearoyl-ACP desaturase (SAD), fatty acid acyl-ACP thioesterase (FATA), and diacylglycerol acyltransferase (DGAT) genes, which were mainly induced by nitrogen limitation. Furthermore, BAP and GA produced a significant over-expression on these genes in the N-replete cultures. This study shows that BAP and GA, coupled to N limitation stress, can be used to increase the biomass and lipid production in S. obliquus for sustainable biofuels.
European Journal of Lipid Science and Technology
Journal of Applied Phycology
European Journal of Lipid Science and Technology
European Journal of Lipid Science and Technology, 2016
Biotechnology Progress, 2016
Microalgae have the potential to accumulate triacylglycerols (TAGs) under different light spectra... more Microalgae have the potential to accumulate triacylglycerols (TAGs) under different light spectra. In this work Chlamydomonas reinhardtii was grown under white (400-700 nm), red (650 nm) and green (550 nm) lights. According to our results, red light (650nm) has a positive effect in the microalgae growth and chlorophyll concentration. Regarding the lipid content, the control culture (white light-illuminated) reached a 4.4% of dry cell weight (dcw) while the culture grown at 550nm showed an increase in the lipids accumulation of 1.35-fold (5.96% dcw). Interestingly, the most significant accumulation was found in the culture grown at 650nm (14.78% dcw) which means 3.36-fold higher with respect to the white light-illuminated culture. The most abundant fatty acids found in lipid extracts obtained from the cultures under different light wavelength were palmitic (C16: 0), oleic (C18: 1n9), stearidonic (C18: 4) and linoleic (C18: 2), which are useful in the biodiesel production. Changes in gene expression in response to different wavelength illuminations were assessed; however an in-depth analysis of a larger number of genes involved in lipid biosynthesis is necessary to fully explain the highest accumulation of lipids in the culture grown under red light. This approach will be useful to find a sustainable source of lipids for biodiesel production. This article is protected by copyright. All rights reserved.
PLOS ONE
A collection of evidence suggests that conjugation of double bonds of eicosapentaenoic (EPA) and ... more A collection of evidence suggests that conjugation of double bonds of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, omega-3 polyunsaturated fatty acids (n-3 PUFAs), increases their anticarcinogenic activity; however, the effect of such conjugation on vascular tone activity remains unknown. We propose that the mixture of conjugated PUFAs exerts higher vasorelaxation activity than the corresponding mixture of nonconjugated PUFAs. The vascular response to different concentrations of conjugated and nonconjugated isomers of EPA and DHA, among other fatty acids (FAs) naturally present in shark oil, and the role of nitric oxide (NO) as a vasorelaxant agent were investigated. Both conjugated EPA (CEPA) and conjugated DHA (CDHA) were prepared by alkaline isomerization of all PUFAs contained in shark oil. Different concentrations of conjugated and nonconjugated PUFAs were placed in contact with precontracted aortic rings of Wistar rats to assess their effect on vascular tone. All tested samples exerted a vasorelaxant effect. Compared to nonconjugated PUFAs, conjugated isomers exhibited an increase in the dilatation of the aortic rings (P<0.001) in a dose-dependent manner (P<0.001). In addition, nonconjugated PUFAs produced nitric oxide (NO) in a dose-dependent manner, while conjugated PUFAs did not, suggesting that their dilatation mechanism is not totally dependent on NO.
Methods of selective production of cis-9, trans-11- and trans-10, cis-12- isomers of conjugated l... more Methods of selective production of cis-9, trans-11- and trans-10, cis-12- isomers of conjugated linoleic acid (CLA) are of big interest due to the biological properties that have been reported for such compounds. Moreover, they naturally exist mainly in fats from ruminants at very low concentration. In this work, the chemical synthesis of CLA by alkali isomerization of linoleic acid contained in safflower oil was investigated, by modifying an actual industrial process in order to improve the concentration of the CLA isomers of interest, and make the product good for human consumption. Here, propylene glycol was used as solvent instead of ethylene glycol (a toxic solvent). The change in solvent resulted in a low conversion, as response, catalyst (NaOH) concentration and reaction time had to be adjusted in order to maximize the CLA production. The optimal conditions found here were: 7% NaOH in propylene glycol, and a reaction time of 2.15 h. Under such set of conditions a conversion o...
Journal of Biotechnology, 2014
The high demand for less polluting, newer, and cheaper fuel resources has increased the search of... more The high demand for less polluting, newer, and cheaper fuel resources has increased the search of the most innovative options for the production of the so-called biofuels. Chlamydomonas reinhardtii is a photosynthetic unicellular algae with multiple biotechnological advantages such as easy handling in the laboratory, a simple scale-up to industrial levels, as well as a feasible genetic modification at nuclear and chloroplast levels. Besides, its fatty acids can be used to produce biofuels. Previous studies in plants have found that the over expression of DOF-type transcription factor genes increases the synthesis and the accumulation of total lipids in seeds. In this context, the over-expression of a DOF-type transcription factor in C. reinhardtii was applied as approach to increase the amount of lipids. The results indicate higher amounts (around 2-fold) of total lipids, which are mainly fatty acids, in the genetically C. reinhardtii modified strains when compared with the non-genetically modified strain. In order to elucidate the possible function of the introduced Dof-type transcription factor, we performed a transcription profile of 8 genes involved in fatty acid biosynthesis and 6 genes involved in glycerolipid biosynthesis, by quantitative real time (qRT-PCR). Differential expression profile was observed, which can explain the increase in lipid accumulation. However, these strains did not show notable changes in the fatty acid profile. This work represents an early effort in generating a strategy to increase fatty acids production in C. reinhardtii and their use in biofuel synthesis.
Journal of the American Oil Chemists’ Society, 1993
The adsorption of peroxides, unsaturated carbonyls, free fatty acids and carotenoids from unrefin... more The adsorption of peroxides, unsaturated carbonyls, free fatty acids and carotenoids from unrefined sesame oil on vegetable carbon (5%, w/w) in a misceUa system was studied. Three different solvent conditions {hexane/ethanol, 100:0, 95:5 and 75:25, vol/vol), combined in a factorial design with five levels of solvent (0, 10, 20, 30 and 40%, w/w), were used to develop the miscella. Equilibrium adsorption was not achieved during the 100 rain of adsorption, mainly because the oil components were involved in oxidation reac~ tions during the adsorption process. However, for a given solvent concentration, adsorption of the oil components showed a significant linear regression on their respective initial concentration in the miscella (Ci). Peroxides and carbonyls showed, at all solvent levels investigated, an affinity for the carbon more independent of their Ci than free fatty acids and carotenoids. In general, at the same Ci, a higher adsorption was achieved as solvent concentration increased. The results indicated that free fatty acid adsorption may depend on competitive adsorption based on molecule hydrophobicity. However, in spite of the higher hydrophobicity of carotenoids, compared with free fatty acids, they might not be competing for the same adsorbing sites. Ethanol showed a prooxidant effect that increased peroxide production during adsorption but did not affect the reaction involved in carbonyl production.
Journal of the American Oil Chemists' Society, 2004
Lipase-catalyzed acidolysis of different TAG with CLA was performed to produce structured lipids ... more Lipase-catalyzed acidolysis of different TAG with CLA was performed to produce structured lipids (SL) containing CLA. An immobilized lipase from Mucor miehei (Lipozyme IM, Novo Nordisk Inc., Franklinton, NC) was used as the biocatalyst in a solvent-free system. Coconut oil and tricaprylin, which are sources of medium-chain FA, were the starting substrates, and a mixture of FFA (MFFA) containing 73% CLA was the donor of the acyl groups. For each TAG, four different ratios of TAG/MFFA were blended to prepare about 500 g of mixture containing 10, 20, 30, and 40% CLA (w/w). Each blend was reacted with 5% lipase at 65°C for 48 h under nitrogen. Over the range of TAG/ MFFA ratios examined, CLA was incorporated effectively by the enzyme. Lipozyme IM exhibited no special preference for any particular FA, since the incorporation of FA was proportional to their concentration in the system. FFA, PV, p-anisidine value (p-AV), iodine value (IV), and saponification number (SN) were evaluated for all the SL. FFA, PV, and p-AV depended on the purification process and showed no significant deterioration of SL with respect to the original TAG, whereas IV and SN depended on the composition of the SL, mainly the CLA content.
Specific structured lipids (SSL), previously produced by enzymatic acidolysis of coconut oil with... more Specific structured lipids (SSL), previously produced by enzymatic acidolysis of coconut oil with different levels of conjugated linoleic acid (CLA) as fatty acid (FA), using a sn-1, 3 specific immobilized lipase, were used to prepare randomized structured lipids (RSL). A fraction of each SSL was subjected to chemical interesterification with sodium methoxide catalyst in order to modify the FA positional distribution and produce the corresponding RSL. Both families of structured lipids (SL) containing CLA were physicochemically characterized. Then, analysis of variance (ANOVA) was performed to evaluate the effects of CLA content (10, 20, 30 and 40%) and FA positional distribution (specific and randomized) on physicochemical properties of SL. Free fatty acids (FFA), peroxide value (PV) and p-anisidine value (p-AV) were not significantly affected by either CLA content or distribution. As expected, the iodine value (IV) and saponification value (SV) were influenced by CLA content but not by FA positional distribution, while oxidative stability index (OSI) was affected by both factors. Dropping point (DP), cloud point (CP) and solid fat content (SFC) decreased with the increase of CLA, while viscosity increased with the level of CLA. The FA positional distribution affected practically all the evaluated physical properties of SL, except CP and DP.
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Papers by Alejandro Rocha Uribe