Fatty Acid Ethyl Esters Content Research Articles

A green approach to obtaining concentrated lipophilic bioactives from oil-rich extracts via biocatalytic alcoholysis in supercritical carbon dioxide

A novel green method to concentrate β-carotene was developed by (i) ethanolysis of triolein using a commercial immobilized lipase (Novozym 435) in a supercritical carbon dioxide (SC-CO2) bioreactor, and (ii) isolation of the produced fatty acid ethyl esters (FAEEs) from the reaction mixtures by taking the advantage of the tunable solvent properties of SC-CO2. The effects of enzymatic reaction conditions (temperature (45–65 °C), pressure (8–15 MPa), enzyme load (10–20%), and substrate mole ratio of triolein to ethanol (1:3–1:9)) on the conversion were investigated and optimized based on the FAEE content of the reaction products. The reaction carried out at 55 °C, 15 MPa, 20% enzyme load, and 1:6 substrate mole ratio in 8 h resulted in the highest FAEE content (93.3%). The isolation of FAEEs from the reaction mixtures was studied using both static and continuous SC-CO2 extractions at various temperatures (40–60 °C) and pressures (10–20 MPa). The highest FAEEs yield (89.9%) was achieved with a continuous extraction at 40 °C and 20 MPa for 4 h, where the FAEE extract (96.3% purity) has a great potential to be used as biodiesel, a sustainable alternative to petroleum diesel. Owing to the high extraction yield of FAEEs from the reaction mixture, the concentration of β-carotene was significantly increased by 9.3-fold. The proposed approach is a green, food-grade approach to produce β-carotene concentrate that can be utilized in smaller amounts to develop functional foods with health-promoting effects.

Triethanolamine-based deep eutectic solvents as cosolvents in biodiesel production from black mustard (Brassica nigra L.) seed oil

The application of triethanolamine (TEOA)-based deep eutectic solvents (DESs) with glycerol (G), propylene glycol (PEG), 1,3-dimethylurea (DMU), ethylene glycol (EG), menthol (M), oleic acid (OLA), decanoic acid (DEA), and choline chloride (ChCl) (1:1, 1:2 or 2:1 mol/mol) in the CaO-catalyzed black mustard seed oil (BMSO) ethanolysis was studied. The ethanolysis was performed at 70 ºC, 12:1 ethanol-to-oil molar ratio, 20% DES, and 10% CaO (to BMSO). It was accelerated by the DESs with G, PEG, ChCl, DMU, M, and DEA and resulted in a higher fatty acid ethyl ester (FAEE) content (≥95.2 ± 0.6%) in 15 min than the control reaction. The TEOA:ChCl DES was most effective, providing within only 1.5 min an FAEE content of about 98.5%. With the TEOA:M and TEOA:PEG DESs, the FAEE content of over 91% was achieved for this time. Furthermore, the final product separation was achieved faster with all the applied DES than in the control reaction. With the TEOA:M and TEOA:ChCl DESs, separation was achieved immediately after the stopping of mixing and for 1 min, respectively. Two kinetic models were used for modeling the BMSO ethanolysis over CaO assisted by the TEOA:ChCl DES. The CaO reusability in three runs exceeded the FAEE content of 90%.

Biodiesel production from rice bran oil fatty acid distillate via supercritical hydrolysis–esterification–transesterification in a microreactor

Rice bran oil fatty acid distillate (RBOFAD), a by-product from rice bran oil production, was used as feedstock for the production of biodiesel. The hydrolysis–esterification–transesterification of RBOFAD with ethanol was performed in a microreactor under supercritical conditions. The biodiesel product in the form of fatty acid ethyl ester (FAEE) was obtained. The operating conditions, including the sulfuric acid content (0.2–0.6%), water content (0–7.5%), ethanol-to-oil molar ratio (5:1–16:1), and reaction temperature (260–320 °C), were optimized. The water content could affect the reaction system via both hydrolysis of triglycerides and reverse esterification of fatty acids. Biodiesel with the FAEE content of 93% was obtained at the optimal conditions (sulfuric acid content of 0.4%, water content of 2.5%, ethanol-to-oil molar ratio of 7:1, residence time of 19 min, and reaction temperature of 280 °C). The properties of the biodiesel, including density, viscosity, acidity, oxidation stability, freezing point, and pour point, were compared with standards. The properties such as viscosity, acid value, heating value, and oxidation stability were suitable as biodiesel according to EN14213, except for the contents of ester, monoglyceride, and diglyceride.

Production of ethyl esters from forage radish seed: An integrated sequential route using pressurized ethanol and ethyl acetate

This work investigated the production of fatty acid ethyl esters (FAEE) from forage radish seeds using a sequential process with pressurized ethanol and ethyl acetate as solvents and acyl acceptors. First, the effect of the solvent on the extraction was determined and subsequently, the sequential reaction was carried out with the material from the pressurized liquid extraction (PLE) where the effects of temperature, residence time and water concentration were investigated. Conventional extraction was carried out for comparative purposes with regards to the oil quality of the PLE and its efficiency in the reaction. The use of ethanol resulted in a high mass yield, which was attributed to the high non-lipid fraction in the extracted material, and ethyl acetate retained proteins, phenolic compounds and sugars in the defatted meal. The main fatty acids in the oil were oleic and erucic acids and high levels of minority compounds were observed in the PLE oil. In the sequential reaction, supercritical ethyl acetate at 300 °C provided the highest FAEE content (42 wt% in 25 min). The addition of water in the acyl acceptor increased the production of FAEE, reduced the thermal degradation of the esters and provided a product with low levels of acylglycerols. Oils from PLE and conventional extraction showed similar performance in the synthesis of esters. Ethyl linolenate and ethyl linoleate were the esters that showed the highest level of degradation. The highest content of FAEE (53 wt%) was reached at 300 °C with 20% (v/v) of water, resulting in a triacetin content of 0.92 wt%.

Fatty acid ethyl esters production from distillers corn oil by enzymatic catalysis

AbstractDistillers corn oil (DCO), a by‐product from the corn ethanol production, is an alternative source of glycerides to produce biodiesel. In the present work, this feedstock was enzymatically converted into fatty acid ethyl esters (FAEE). DCO presented relative density of 0.912 g/cm3, peroxide index of 3.05 ± 0.3 (meq/1000 g of sample) and acidity of 13.1 ± 1.96 (wt.%), with prevalence of the oleic (18:1) and linoleic (18:2) acids (sum equal to 76.9%). Three strategies were evaluated to improve the FAEE content: ethanol stepwise addition (ethanol:oil molar ratio of 4:1 (1/2 of ethanol at 0 and 1.5 h) and 3:1 (1/3 of ethanol at 0 h and 2/3 at 1.5 h or 1/3 of ethanol at 0, 1 and 2 h)); consecutive reactions (with Novozym 40086 [Rhizomucor miehei lipase] as biocatalyst); and mixture of enzymes (Novozym 40086 (6 wt.%) + Novozym 435 (Candida antarctica B lipase) (2 wt.%). The concept of combi‐lipases was evaluated for the first time using this raw material, resulting in a high ester content (>96%). The higher ester yields attained with DCO, compared to refined corn oil (33%) can be related to the better solubilization of ethanol and/or glycerol by‐product in the medium with DCO. The combi‐lipase system kept high than 80% of this initial activity after three repeated batches of reaction. The use of DCO enables the integration of corn ethanol and biodiesel production within the same general facility, which has logistic, environmental and, economic relevance.

Classification of olive fruits and oils based on their fatty acid ethyl esters content using electronic nose technology

Classification of olive fruits and oils based on their fatty acid ethyl esters content using electronic nose technology

Development and validation of a simple and reliable alternative method for process monitoring and final product quality control during fatty acid ethyl esters production

As the production of biofuels increase, there is an urgent need to easily analytically control their production at the plant level as well as to assess the quality of the final products. Especially method capable of determining fatty acid ethyl ester content of 96.5% is crucial for utilization in praxis. In this work, a refractive index method with required sensitivity was developed and validated by means of a standard reference gas chromatography method. Validation with a considerable set of real unique samples obtained at pilot scale was performed for both purposes – process monitoring at high conversions and final product quality control. The results confirmed a favourable degree of accuracy with a relative deviation lower than 3.5% from the reference value given by the gas chromatography. Moreover, application of the method for quality control of fresh and long-term stored samples revealed that the deterioration of final products during storage can be detected. The developed refractive index method is thus suitable for the simple and rapid evaluation of the quality of produced fatty acid ethyl esters and for analytical monitoring of their production process.

Catalyst-free production of fatty acid ethyl esters (FAEE) from macauba pulp oil

In this study, the production of fatty acid ethyl esters (FAEE) from macauba pulp oil and pressurized ethanol was investigated. The experiments were conducted without the addition of catalyst, at 20 MPa, to determine the effect of temperature (200 to 300 °C) and the oil to ethanol mass ratio (1:1 and 1:2) on the FAEE content and different residence times (10 to 45 min). The effect of the addition of n-hexane to the oil (20 wt%) as a co-solvent was also evaluated. The use of high temperatures (275 and 300 °C) resulted in high FAEE content (∼90%). Increasing the amount of ethanol in the reaction medium contributed to the formation of esters only at operating temperatures of 200 to 250 °C. It was also observed that with the addition of co-solvent (in the oil) it was possible to obtain high amounts of FAEE in a shorter reaction time. In addition, a low content of unreacted compounds (∼8.0%) and the conversion of ∼90 and 99% of the free fatty acids and triglycerides were observed, respectively.

Fatty acid ethyl esters in virgin olive oils: a correlation study with the volatile profile

Fatty acid ethyl esters are the newest mandatory quality parameters introduced for extra virgin olive oil classification linked to fermentative processes occurring in low-quality olives. Although it is clear the strong linkage of ethyl esters with sensory fermentative defects there is a lack of knowledge about their relationship with specific volatile compounds. Hence, a study was carried out to evaluate the correlation among extra virgin olive oil quality indices and its respective volatile profile with fatty acid ethyl esters. Thirty-five virgin olive oils were collected from local oily industry and analysed for the fatty acid ethyl esters content, the basic quality parameters, the total phenolic content and the volatile profile. The obtained results showed that the fatty acid ethyl esters were negatively correlated to total phenolic compounds (p<0.05) and trans-2-hexenal content (p<0.001) while positively correlated (p<0.001) to ethyl acetate and ethyl acetate/trans-2-hexenal and ethyl acetate/hexanal ratios. Interestingly, ethanol was not correlated at all with the ethyl esters content in oils.

FT-IR extra virgin olive oil classification based on ethyl ester content

According to the Regulation (EU) 2016/2095, extra virgin olive oils (EVOO) must contain a maximum of 35 mg kg−1 of fatty acid ethyl esters (FAEE). The official method for FAEE quantification is time-consuming and requires the use of a large amount of toxic solvents. Thus, the aim of this work was the application of FT-IR spectroscopy for the development of classification models (i.e. Linear Discriminant Analysis, LDA; Soft Independent Modelling of Class Analogy, SIMCA) able to discriminate EVOO from non-EVOO based on FAEE content. To the aim, 113 EVOO and 46 non-EVOO samples were analysed. Since the Principal Component Analysis revealed that the whole FT-IR spectral range (both raw or pre-treated) was not promising in EVOO and non-EVOO distinction, a variable selection strategy was applied (i.e. SELECT algorithm). All the classification models were validated both by cross validation and with three different external test sets. The best and more robust LDA model was obtained with the raw FT-IR selected variables, reaching 96–100% of correct classification in prediction. SIMCA models resulted less reliable. In particular, the low specificity values (40–67%) revealed that there is a high probability of assignment of non-EVOO to the EVOO class. In conclusion, FT-IR spectroscopy coupled with a discriminant classification approach is a useful tool for a rapid and fast discrimination of EVOO and non-EVOO based on FAEE content. Since the variable selection strategy was effective, the development of simplified and cheap instruments can boost the FT-IR spectroscopy application also in small enterprises, giving the opportunity to acquire many important information about olive oils.

Influence of various cosolvents on the calcium oxide-catalyzed ethanolysis of sunflower oil

Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 ?C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol?L-1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7?1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two provided a final FAEE content of 93.1?2.1 and 94.1?1.5 %, respectively, within 0.5 h. However, because of its safety profile, triethanolamine was selected as the best cosolvent for the ethanolysis of sunflower oil catalyzed by calcined CaO.

Modeling of biodiesel production: Performance comparison of Box–Behnken, face central composite and full factorial design

Abstract The performances of the response surface methodology (RSM) in connection with the Box–Behnken, face central composite or full factorial design (BBD, FCCD or FFD, respectively) were compared for the use in modeling of the NaOH-catalyzed sunflower oil ethanolysis. The influence of temperature, catalyst loading, and ethanol-to-oil molar ratio (EOMR) on fatty acid ethyl esters (FAEE) content was evaluated. All three multivariate strategies were efficient in the statistical modeling and optimization of the influential process variables but BBD and FCCD realization involved less number of experiments, generating smaller costs, requiring less work and consuming shorter time than the corresponding FFD. All three designs resulted in the same optimal catalyst loading (1.25% of oil) and EOMR (12:1). The reduced two-factor-interaction (2FI) models based on the BBD and FCCD defined a range of optimal reaction temperature (25 °C–75 °C) and 25 °C, respectively while the same model based on the 33 FFD appointed 75 °C. The predicted FAEE content of about 97%–98.0% was close to the experimentally obtained FAEE content of about 97.0%–97.6% under the optimal reaction conditions. Therefore, the simpler BBD or FCCD might successfully be applied for statistical modeling of biodiesel production processes instead of the more extensive, more laborious and more expensive FFD.

The production of the Chinese baijiu from sorghum and other cereals

Baijiu is a widely consumed spirit usually distilled from fermented sorghum. Here the use of other cereal grains (wheat, corn, rice and barley) is compared with sorghum. The concentration of ethyl acetate in spirit made from sorghum was found to be higher than in the spirits made using other grains, whereas the concentrations of aldehydes and higher alcohols were lower. Based on sensory evaluations, the flavours were more satisfactory when sorghum was used for making Baijiu. Of the other cereals, the flavour from wheat was better than those of corn, rice and barley for making Baijiu. The ester concentration of the spirit made from the rice was low, whereas aldehyde and alcohol contents were high. An abnormal flavour was found in spirits made from corn or barley. Further work with sorghum showed variations in tannin content, and a correlation between the tannin content and brewing performance. When the content of tannin was <1.94%, the ethyl acetate and ethyl octanoate content were positively correlated with tannin content. In contrast, the ethyl lactate and higher fatty acid ethyl esters content were negatively correlated with tannin content. The results of flavour analysis and sensory evaluation indicated that the ideal sorghum tannin content for producing Baijiu was between 1.0 and 2.0%. Copyright © 2017 The Institute of Brewing & Distilling

Panel test and chemical analyses of commercial olive oils: a comparative study

BackgroundThe quality grade of an olive oil is defined according to the results of analytical and organoleptic examinations.The increasing attention towards both olive oil quality and quality verification methods prompted us to undertake a “critical” analysis of analytical and sensory data supplied by an International Certificated Body (ICB), relative to commercial olive oils produced in Mediterranean areas and purchased in Italy and in USA.MethodsICB data included chemical analyses namely free acidity, peroxide index, spectrophotometric UV evaluation, fatty acid ethyl esters and stigmadiens content and organoleptic evaluations carried out by nine official International Olive Council labs according to EEC Regulation 2568/91.ResultsThe results of the chemical analyses, except the fatty acid ethyl ester content, obtained from the nine labs were consistent giving rise to the same quality grade. In nearly all samples, the fatty acid ethyl ester content was close to the threshold established for extra virgin olive oils indicating a non-excellent quality of the olive oils. Organoleptic evaluations, commonly called panel test, given by the nine labs were not consistent.ConclusionsThe EEC Regulation 2568/91 does not give any indication on the way to report the uncertainty of the results, and in the case of extra virgin olive oils with a borderline value, the way to report the fatty acid ethyl ester content, with or without the uncertainty, can create confusion in defining the olive oil quality grade. Panel test seemed to work well only in the case of extremely good olive oils, whereas, in commercial extra virgin olive oils with borderline value of fatty acid ethyl ester content, a different sensory sensibility seems to be in the different IOC labs.Graphical abstractPanel test and chemical analyses of commercial olive oils: a comparative study.

Increase of medium-chain fatty acid ethyl ester content in mixed H. uvarum/S. cerevisiae fermentation leads to wine fruity aroma enhancement

Medium-chain fatty acid (MCFA) ethyl esters, as yeast secondary metabolites, significantly contribute to the fruity aroma of foods and beverages. To improve the MCFA ethyl ester content of wine, mixed fermentations with Hanseniaspora uvarum Yun268 and Saccharomyces cerevisiae were performed. Final volatiles were analyzed by gas solid phase microextraction-chromatography-mass spectrometry, and aroma characteristics were quantitated by sensory analysis. Results showed that mixed fermentation increased MCFA ethyl ester content by 37% in Cabernet Gernischt wine compared to that obtained by pure fermentation. Partial least-squares regression analysis further revealed that the improved MCFA ethyl esters specifically enhanced the temperate fruity aroma of wine. The enhancement of MCFA ethyl esters was attributed to the increased contents of MCFAs that could be induced by the presence of H. uvarum Yun268 in mixed fermentation. Meanwhile, the timing of yeast inoculations significantly affected the involving biomass of each strain and the dynamics of ethanol accumulation.

Simultaneous Enzymatic Transesterification and Esterification of an Acid Oil Using Fermented Solid as Biocatalyst

AbstractThis work studied the enzymatic synthesis of fatty acid ethyl esters (FAEE) for potential use as biodiesel via simultaneous esterification and transesterification of acid oil from macaúba in a solvent‐free system. A fermented and dry babassu cake with lipase activity from Rhizomucor miehei was used as biocatalyst. FAEE content above 85% was achieved after 96 h of reaction with enzyme loading of 13 U per g of oil, 120 mmol of hydrous ethanol (95% ethanol and 5% water)/20 mmol of oil (molar ratio ethanol:oil of 6:1), at 40 °C. After two consecutive enzymatic reactions, 90.8 wt% FAEE content was obtained. These results demonstrate a promising transesterification/esterification method for FAEE production from an acid and low‐cost oil and the process has potential to decrease the costs of enzymatic biodiesel production.

ESTRATEGIAS DE MEJORA PARA LA PRODUCCIÓN ENZIMÁTICA DEBIODIESEL EN PRESENCIA DE ALCOHOLES PRIMARIOS

In order to improve the enzymatic production of biodiesel, the reuse of an immobilized preparation of Candida antarctica lipase B (CALB) was assayed under di ff erent conditions. The improvement included: (1) reuse of CALB in the presence of ethanol (EtOH), (2) reuse of CALB in the presence of methanol (MeOH), (3) blended alcohols at di ff erent molar ratios (0:100, 20:80, 40:60, 50:50, 60:40, 80:20 and 100:0, %EtOH:%MeOH), and employing second generation raw materials: waste cooking oil (WCO) and castor oil (CO). When the first strategy was carried out the FAEE (fatty acid ethyl ester) content achieved was 96% in a first cycle but after four cycles the percentage decreased to 32%. For the second strategy the FAME (fatty acid methyl ester) content attained was 63% in a first cycle but after four cycles the percentage was only 13.5%. When the blended alcohols were tested, the negative e ff ect of MeOH was evident for higher concentrations regardless the type of oil used.

Evaluation of Proton Nuclear Magnetic Resonance Spectroscopy for Determining the Yield of Fatty Acid Ethyl Esters Obtained by Transesterification

This study systematically evaluates the use of proton nuclear magnetic resonance (1H NMR) spectroscopy for determining the composition of soybean oil ethyl transesterification product mixtures by comparing the compositions measured by 1H NMR spectroscopy and high-performance liquid chromatography (HPLC). The influence of the sample composition on the results is also discussed. For many of the samples, the triacylglycerol (TAG), diacylglycerol (DAG), monoacylglycerol (MAG), and fatty acid ethyl ester (FAEE) contents could be determined by HPLC. When the conversion of the TAGs into FAEEs is incomplete, the evaluation of the FAEE content by 1H NMR spectroscopy must be performed with caution because of overlapping signals in the spectrum. In this study, three equations were used to calculate the ethyl ester content from the 1H NMR results. The contents calculated using eq 3 agree with the HPLC results the best, as shown by the slope obtained by linear regression of the two data sets.

Optimization of sunflower oil ethanolysis catalyzed by calcium oxide: RSM versus ANN-GA

The ethanolysis of sunflower oil catalyzed by calcium oxide was modeled and optimized in terms of the following operating conditions: reaction temperature (65–75°C), ethanol:oil molar ratio (6:1–18:1), catalyst loading (10–20% based on oil weight) and reaction time (360–480min). Response surface methodology (RSM) and artificial neural network (ANN) approaches were used for modeling the content of fatty acid ethyl esters (FAEE) and optimizing the four process variables. Both models were determined to be reliable in terms of predicting the FAEE content, but the ANN model was found to be more accurate than the RSM model. The highest FAEE content of 99.2% was determined using the ANN model combined with a genetic algorithm optimization method, which agreed well with the experimental value (97.8%). A good agreement between the predicted and actual maximum FAEE contents was observed for both models. The generalization of the ANN model developed for heterogeneously catalyzed alcoholysis was also tested on several oily feedstocks.

Transgenic Corn Oil for Biodiesel Production via Enzymatic Catalysis with Ethanol

This work aims to study the production of fatty acid ethyl esters (FAEE) from a transgenic corn oil, through transesterification using supported enzymes as catalyst (Lipozyme TL IM from Novozymes) and ethanol as reagent. First, the corn oil was characterized for its acid value (0.26 mg KOH/g oil), iodine number (127 g iodine/100 g oil), kinematic viscosity at 40 °C (36.27 mm2/s), density at 20 °C (919 kg/m3) and water content (749 mg/kg). Second, the best operating conditions to perform the transesterification reaction were determined, by testing the following experimental conditions: oil/ alcohol molar ratio (1:3, 1:6 and 1:9), catalyst/ oil mass ratio (2.3, 2.8 and 3.3 wt%), reaction time (8 and 12 h) and reaction temperature (35 and 45 °C). Results showed that although some of the quality parameters analyzed were out of the EN 14214:2009 standard limits (namely the kinematic viscosity, water content, acid value and group I metals) the best operating conditions for a good biodiesel quality (with 69.2 wt% of FAEE content) and the highest reaction yield (98.95 wt%) are an oil/ alcohol molar ratio of 1:6, a catalyst/ oil mass ratio of 2.8 wt%, a reaction time of 12 h and a reaction temperature of 35 °C.