Thermal degradation of prions in the presence of fats: Implication for oleochemical processes

Bovine tallow is widely used as raw material for oleochemical processes, i.e. the manufacturing of fatty acids and glycerol and their derivatives. The basic oleochemical process, i.e. the hydrolytic fat splitting under industrial conditions of 200–260 °C at corresponding pressure and a minimum residence time of 20 min, is considered to guarantee the safety of all tallow‐derived products. As to the present day no experimental data on the safety of fatty acids and glycerol in case of a hypothetical contamination of tallow with TSE agents under technically relevant conditions are available, the intention of this study was to provide quantitative data for the destruction of prions. This short communication reports the first part of a research project simulating prion inactivation under manufacturing conditions of the upper part of industrial fat‐splitting columns (fatty acid regime) on a laboratory scale. To establish worst‐case destruction factors, the degradation of prion protein was analysed in dependence upon temperature. The industrial process conditions of the fatty acid regime of hydrolytic fat splitting provide an additional safety factor of at least 1×10⁷, confirming that all fatty acids can be regarded as safe, irrespective of their origin.     

Risk assessment for prion protein reduction under the conditions of the biodiesel production process

Due to the increased demand for biofuels, all different feedstocks from oils and fats have to be considered for biodiesel production. Animal fats have proved to be excellent sources for biodiesel due to their high cetane number and good stability. Large amounts of fat from so‐called high‐risk material, possibly contaminated with infectious prions, are available for biodiesel production. In this paper, the grade of destruction of prions during the biodiesel production process, including pre‐esterification with conc. sulfuric acid followed by KOH‐catalyzed transesterification, was studied. The starting material of the different production steps was spiked with purified and highly infectious prion rods, and the destruction of these prions was determined by gel electrophoresis (SDS‐PAGE) and Western blot. The pre‐esterification step led to a destruction factor of at least 100, the transesterification led to a factor of at least 250, and the distillation of the final biodiesel showed a destruction factor of at least 1000. During all experiments, no traces of prions could be detected after the different reaction steps. Based on these data, a complete and unequivocal risk assessment regarding the industrial process of biodiesel production was carried out, leading to a calculated overall risk of 5.8×10^?15 ID₅₀ units/person and year, which means that a hypothetical BSE contamination from biodiesel is more than 10⁹ times lower than the background risk.     

Biodiesel production from waste tallow

In the present investigation an attempt has been made to use waste tallow as low cost sustainable potential feed stock for biodiesel production. Effect of various process parameters such as amount of catalyst, temperature and time on biodiesel production was investigated. The optimal conditions for processing 5 g of tallow were: temperature, 50 and 60 °C; oil/methanol molar ratio 1:30 and 1:30, amount of H₂SO_4, 1.25 and 2.5 g for chicken and mutton tallow, respectively. Under optimal conditions, chicken and mutton fat methyl esters formation of 99.01 ± 0.71% and 93.21 ± 5.07%, was obtained after 24 h in the presence of acid. The evaluation of transesterification process was followed by gas chromatographic analysis of tallow fatty acid esters. A total of 98.29% and 97.25% fatty acids were identified in chicken and mutton fats, respectively. Both fats were found highly suitable to produce biodiesel with recommended fuel properties.     

Risk assessment for fat derivatives in case of contamination with BSE

Prion diseases are not only of outstanding scientific interest but have also enormous economic impact. In particular, the human food and animal feed industry and even oleochemical manufacturing processes are afflicted. In the oleochemical industry, bovine edible tallow is widely used as raw material for the production of fatty acids, glycerol, and their derivatives. Although there is no evidence that tallow has been a causal factor for BSE nor that infectivity partitions preferentially with tallow, the potential risk associated with tallow‐derived products has to be evaluated in the light of the specific production process. To the present day, no experimental data under technically relevant conditions are available on the safety of fatty acids, glycerol, and their derivatives in the case of a hypothetical contamination of tallow with prions. A risk assessment calculation is provided here based on quantitative data for the degradation of the pathological prion protein as well as the inactivation of prion infectivity. It can be concluded that the industrial conditions of the basic oleochemical process of hydrolytic fat splitting constitute an effective means for reducing the risk of TSE contamination to an acceptable minimum. All industrial tallow‐derived products can be regarded as safe, independently of their origin.     

Formation of formic acid from glycerine using a hydrothermal reaction

BACKGROUND: Glycerine, a main by‐product of the biodiesel manufacturing process, has potential to be an important biorefinery feedstock with the rapid increase in biodiesel production all over the world. Hydrothermal experiments with glycerine were carried out at 250 °C using H₂O₂ as an oxidant. RESULTS: Glycerine was converted into formic acid with a yield of 31.0% based on the starting mass of carbon in glycerine. A possible oxidation pathway for the formation of formic acid from glycerine is proposed. In the proposed pathway, glycerine may first be oxidised and then decomposed into formic acid and oxalic acid. Oxalic acid was indirectly attributed to the increase of formic acid production from glycerine, but it instead acts as a retardant to prevent further oxidation of formic acid. However, when an alkali was added to the experimental conditions, the yield of formic acid was not greatly improved, reaching only 34.7%. CONCLUSION: The present work should help to facilitate further studies to develop a new green process for the production of formic acid from renewable biomass. © 2012 Society of Chemical Industry     

Noncatalytic Biodiesel Fuel Production from Croton megalocarpus Oil

Biodiesel is currently considered as the most promising substitute for diesel fuel because of its similar properties to diesel. This study presents the use of the supercritical methanol method in the production of biodiesel from Croton megalocarpus oil. The reaction parameters such as methanol‐to‐oil ratio, reaction temperature and reaction time were varied to obtain the optimal reaction conditions by design of experiment, specifically, response surface methodology based on three‐variable central composite design with α = 2. It has been shown that it is possible to achieve methyl ester yields as high as 74.91 % with reaction conditions such as 50:1 methanol‐to‐oil molar ratio, 330 °C reaction temperature and a reaction period of 20 min. However, Croton‐based biodiesel did not sustain higher temperatures due to decomposition of polyunsaturated methyl linoleate, which is dominant in biodiesel. Lower yields were observed when higher temperatures were used during the optimization process. The supercritical methanol method showed competitive biodiesel yields when compared with catalytic methods.     

An experimental investigation of biodiesel synthesis from waste canola oil using supercritical methanol

Synthesis of biodiesel from waste canola oil using supercritical methanol is investigated under relatively moderate reaction conditions (240–270 °C/10 MPa) with residence time of 15–45 min and methanol to oil weight ratio of 1:1, 1.5:1 or 2:1. The effects of reaction conditions on the biodiesel yield were studied using design of experiments (DOE). The results showed that reaction time, temperature, and their interaction were the most significant factors on the yield. The highest biodiesel yield of 102% was achieved at 270 °C, 10 MPa, and methanol/oil weight ratio of 2 for 45 min reaction time. The GC–MS analysis of the reaction products showed that the by-product, glycerol, further reacted with methanol, generating methyl ethers of glycerol. Further confirmation of this side reaction was obtained by reacting glycerol and methanol at 270 °C/10 MPa for 15, 30, and 45 min. The experimental results showed these reactions could positively affect the overall biodiesel yield by providing oxygenated compounds such as 3-methoxy-1,2-propanediol, dimethoxymethane, and 2,2-dimethoxypropane as well as methyl palmitate and methyl oleate.     

Improvement of the oxidation stability of biodiesel as prepared by supercritical methanol method with lignin

An antioxidation effect of lignin‐derived products in biodiesel prepared using supercritical methanol (300°C/20 MPa) with molar ratio between rapeseed oil and methanol of 1:42 was studied. It was found that lignin could be decomposed to low molecular compounds that have a free radical‐trapping effect after supercritical methanol treatment. However, longer treatment time decreased the antioxidation effect of the lignin‐derived compounds. Rapeseed biodiesel prepared by supercritical methanol method at 300°C/20 MPa for 20 min with a small amount of added lignin showed an induction period longer than 6 h at 110°C in a Rancimat test. In addition, it was found that lignin had a catalytic effect in biodiesel production using the supercritical methanol method without significantly affecting other fuel properties of the prepared biodiesel. Thus, the study proved that lignin addition provides an inexpensive and technically acceptable way to improve the oxidation stability of biodiesel prepared by the supercritical methanol method with satisfactory fuel properties.     

Optimization of fish-oil-based biodiesel synthesis

In this study, the optimum conditions (methanol/oil mole ratio, temperature, and so on) for producing biodiesel with fish oil (menhaden oil) were established. The length of the carbon chain of fish oil is frequently greater than that of general vegetable oils. Therefore, the use of fish-oil based biodiesel with larger cetane number may improve diesel engine performance and result in a reduction of pollutant emissions. The optimum conditions of the manufacture of biodiesel with menhaden oil were reaction time of 120 min, reaction temperature of 55 °C, methanol/fish oil molar ratio of 12, and alkaline catalyst content of 2.0 wt%. In the performance evaluation of the biodiesel produced, the acid value (0.20 mg KOH/g), kinematic viscosity (4.60 cSt at 40 °C), and higher heating value (42.1 MJ/k) biodiesel quality standards were suitable.     

Optimization of Two-Step Biodiesel Production from Beef Tallow with Microwave Heating

Animal fats are by-products from slaughterhouses that may be utilized as renewable energy source. This study was about biodiesel production from high free fatty acid beef tallow waste using two-step process with microwave heating. Sulfuric acid and NaOH were used as catalysts with methanol for the first esterification and second transesterification step, respectively. Catalyst loadings were between 0.25% and 2.5%, with applied microwave power of 340?W, operation time of 10–50?min, and oil-to-methanol molar ratio between 1:3 and 1:15. These process parameters were optimized using the design of experiments. The yields and properties of the biodiesel were assessed. The results indicated that the two-step process were successful in converting the beef tallow to biodiesel. Statistical analysis of the results showed that significant contributions were from the linear and quadratic terms of these three variables. The optimum conditions for esterification and transesterification were reported. Validity of the predicted models was confirmed by the experimental verification.     

Economic and ecological aspects of biodiesel production over homogeneous and heterogeneous catalysts

The objective of this paper is to highlight the economic and ecological differences of biodiesel production over homogeneous and heterogeneous catalysts in large-scale industrial plants. Comparative economic assessment of the two processes revealed the advantage of the heterogeneous process in terms of higher yield of biodiesel and higher purity of glycerine, lower cost of catalyst and maintenance, with an estimated cumulative impact on the reduction of the operating cost of US$59 per tonne of biodiesel, relative to the homogeneous process. The biggest challenge for its economic competitiveness is its higher energy consumption. The analysis showed that if the energy costs are below US$85 per tonne of biodiesel, the heterogeneous process can be economically viable. The environmental benefits of the heterogeneous process include absence of strong acids and of energy intensive and waste generating glycerine purification step. However, its application would contribute to depletion of fossil energy resources and higher emission of greenhouse gases due to higher energy and methanol consumption.     

Separation of squalene from olive oil deodorizer distillate using supercritical fluids

In this study, an integrated strategy using supercritical fluids for extraction of squalene from olive oil deodorizer distillate (OODD), one of the most important by‐products of the olive oil refining process is presented. First, OODD was esterified in supercritical methanol, and then squalene was extracted from the sample consisting of 66% methyl ester using supercritical CO₂. The extraction conditions, i.e., pressure (88.2–121.8 bar), temperature (41.6–58.4°C) and extraction time (129.6–230.4 min), were optimized via RSM to achieve the highest squalene content. The optimal results were obtained at a temperature of 52.05°C, pressure of 104.8 bar and extraction time of 180 min. Consequently, two kinds of value‐added products such as biodiesel (up to 96% FAME, in extract) and olive squalene (up to 75%, in raffinate) were produced in shorter processing times when compared with distillation results of 70 h. Practical applications: Traditionally, squalene is extracted from liver oil of rare deep‐sea sharks. Here we present the recovery of vegetal squalene in high purity from OODD. Our approach also presents a simple, reliable, and mobile solution. Squalene is widely used in cosmetics as a protective agent and natural moisturizer and as an adjuvant in influenza vaccines.     

Solid/liquid extraction and isolation by molecular distillation of hydroxytyrosol from Olea europaea L. leaves

Molecular distillation, or short‐path distillation (SPD), is particularly appropriate for processing of low‐volatility compounds, which are easily altered at high temperature. Olea europaea L. leaves constitute an olive tree by‐product very interesting for their natural antioxidants content. In this research, molecular distillation technology has been applied to obtain high‐value‐added compounds by the SPD fractionation of an olive tree leaf extract. The process consists of two stages: (a) ethanolic extraction of the olive leaves, followed by incorporation of the extract into glycerine and (b) molecular distillation of the glycerine enriched in olive leaf extract compounds (terpenic and phenolic compounds). Four molecular distillation tests under different conditions were carried out. Results showed that 80.9% 3,4‐dihydroxy‐phenylethanol (hydroxytyrosol) was recovered from the glycerine admixture under a pressure of 1.50–2.00 mbar, a temperature of 190 °C and a feed rate of 15 mL/min.     

Oxidation stability of biodiesel fuel as prepared by supercritical methanol

A non-catalytic supercritical methanol method is an attractive process to convert various oils/fats efficiently into biodiesel. To evaluate oxidation stability of biodiesel, biodiesel produced by alkali-catalyzed method was exposed to supercritical methanol at several temperatures for 30 min. As a result, it was found that the tocopherol in biodiesel is not stable at a temperature higher than 300 °C. After the supercritical methanol treatment, hydroperoxides were greatly reduced for biodiesel with initially high in peroxide value, while the tocopherol slightly decreased in its content. As a result, the biodiesel prepared by the supercritical methanol method was enhanced for oxidation stability when compared with that prepared by alkali-catalyzed method from waste oil. Therefore, supercritical methanol method is useful especially for oils/fats having higher peroxide values.     

Effects of extraction and fractionation pressures on supercritical extraction of cholesterol from beef tallow

Edible beef tallow was extracted by supercritical CO₂ in a dynamic mode at pressures from 138 to 345 bars and temperatures of 40 and 50°C. The lipid fractions were collected at 34.5 bar/40°C. A retrograde behavior of lipid solubility was observed around 170–175 bar. The ranges of the cholesterol concentration [chol.], were 300–450 mg/100 g and 50–200 mg/100 g lipid for the fractions extracted at 138 bar and 345 bar, respectively. Beef tallow was also extracted with sequentially varied pressures of 138, 345 and 138 bars at 40°C and collected at 34.5 bar/40°C. The results showed that after 20 kg CO₂ was used for extracting 100 g of loaded beef tallow the weight of the residual beef tallow remaining in the extractor was 23 g with [chol.] of 49 mg/100 g lipid. The lower [chol.] of the residual beef tallow represents a 60–70% reduction in cholesterol content, when compared with untreated beef tallow where [chol.] ranges from 130 to 160 mg/100 g lipid. To isolate lipid fractions containing higher [chol.], beef tallow was extracted at 345 bar/40°C and then fractionated into three separators connected in series with decreasing pressures of 173 bar, 117 bar, and 34.5 bar at 40°C, respectively. The results showed that the fractions collected from the third separator (34.5 bar) contained concentrated [chol.] ranging from 272 to 433 mg/100 g lipid. The fatty acid analysis revealed that the fractions containing high [chol.] generally consisted of high concentrations of myristic and palmitoleic acids but low concentrations of stearic and oleic acids.     

Statistical optimization for biodiesel production from waste frying oil through two-step catalyzed process

The aim of this work was to investigate the optimum conditions in biodiesel production from waste frying oil using two-step catalyzed process. In the first step, sulfuric acid was used as a catalyst for the esterification reaction of free fatty acid and methanol in order to reduce the free fatty acid content to be approximate 0.5%. In the second step, the product from the first step was further reacted with methanol using potassium hydroxide as a catalyst. The Box-Behnken design of experiment was carried out using the MINITAB RELEASE 14, and the results were analyzed using response surface methodology. The optimum conditions for biodiesel production were obtained when using methanol to oil molar ratio of 6.1:1, 0.68 wt.% of sulfuric acid, at 51 °C with a reaction time of 60 min in the first step, followed by using molar ratio of methanol to product from the first step of 9.1:1, 1 wt.% KOH, at 55 °C with a reaction time of 60 min in the second step. The percentage of methyl ester in the obtained product was 90.56 ± 0.28%. In addition, the fuel properties of the produced biodiesel were in the acceptable ranges according to Thai standard for community biodiesel.     

Preparation of a CaO Nanocatalyst and Its Application for Biodiesel Production Using Butea monosperma Oil: An Optimization Study

CaO nanoparticles (NP) were synthesized through solution combustion using crude glycerin (biodiesel by‐product) as the combustion fuel. The synthesized CaO NP were characterized using Fourier transform infrared spectrometer (FTIR), X‐ray diffractometer (XRD), temperature programmed desorption of carbon dioxide (CO₂‐TPD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The CaO NP were successfully used as a catalyst for biodiesel synthesis. Response surface methodology was used to determine the optimal conditions for biodiesel production from Butea monosperma oil (BMO) using central composite design. A total of 20 experiments were designed and conducted to study the effects of the methanol to BMO molar ratio, reaction time, and catalyst loading conditions on the biodiesel yield. A yield of 96.2% of Butea monosperma methyl ester (BMME or biodiesel) was obtained under optimum conditions, namely a molar ratio (methanol to BMO) of 9:1, a reaction time of 70 min, a catalyst loading of 1.60 wt%, a constant temperature of 65 °C, and an agitation speed of 600 rpm. The fatty‐acid composition of BMO was characterized through gas chromatography. Finally, BMME was characterized using FTIR, ¹H NMR, and ¹³C NMR, and the fuel properties of BMME were determined using the test methods of the American Society for Testing and Materials.     

Study of variables affecting the synthesis of biodiesel from Madhuca Indica oil

Biodiesel derived from non‐edible Madhuca Indica oil (MIO) seems to be a better alternative to diesel oil in India. In the present work, effects of reaction variables such as mass ratio of methanol to oil, catalyst concentration, reaction time and reaction temperature on biodiesel yield were studied. The acid value of the commercially available MIO is high, and hence a two‐step process was used to produce biodiesel from MIO. In the first step, the acid value of the MIO was reduced to less than 1 mg KOH/g, using acid‐catalyzed transesterification. In the second step, the pretreated MIO was converted to biodiesel using alkaline‐catalyzed transesterification. From the experimental results, it is observed that the optimized conditions for biodiesel production are a 1 : 4 mass ratio of methanol to oil, 55 °C reaction temperature, 120 min of reaction time, and 1% sodium hydroxide catalyst. The properties of the MIO biodiesel were found to be within the biodiesel limits of the European Union. Hence, the MIO biodiesel can be used as a substitute for diesel for the sustainable development of rural areas and as a renewable fuel.     

Prion decontamination during the oleochemical process of fat hydrogenation

The human food and animal feed industry and even oleochemical manufacturing processes might be exposed to contamination from products of BSE‐infected cattle. Although the most important oleochemical raw material, i.e. tallow, is not considered to be a causal factor for BSE, the potential risk associated with tallow‐derived products has to be evaluated in the light of the specific production process. The main production process for oleochemicals, i.e. hydrolytic fat splitting of tallow yielding glycerol and a mixture of crude fatty acids, guarantees prion‐free products, safe for human consumption [1]. Fatty acids, however, are not necessarily produced by hydrolytic fat splitting. In order to evaluate these fatty acids with regard to prion safety, we analysed the industrial conditions of catalytic fat hydrogenation, which is widely applied to improve storage and flavour stability of fatty acids. Quantitative data for the degradation of the pathological prion protein and the inactivation of prion infectivity are presented. A risk assessment calculation demonstrates that the industrial conditions of fat hydrogenation are sufficiently effective to reduce the risk of BSE contamination to an acceptable minimum.     

Two approaches in preparation for cogeneration α‐tocopherol and biodiesel from cottonseed

A two‐step process and a direct alkaline transesterification process in preparation for cogeneration α‐tocopherol and biodiesel (fatty acid methyl esters, FAME) from cottonseeds were studied in this article. The effects of some factors on recovery of α‐tocopherol and conversion of cottonseed oil (triacylglycerols, TAGs) to biodiesel in the two processes were systematically studied by single factor experiments and orthogonal design method. In the two‐step process, α‐tocopherol and biodiesel were produced from extraction with two‐phase solvent followed by base‐catalysed transesterification. Approximately 95.5% TAGs was converted into biodiesel, and 1.008 mg/g (wet basis) α‐tocopherol was detected on the condition: 1:3 petroleum ether/methanol volume rate, 40°C extraction temperature; 7:1 methanol/cottonseed oil molar ratio, 1.1% KOH (w/v) concentration in methanol and 60°C esterification temperature. And in the direct alkaline transesterification reaction, 98.3% conversion of TAGs and 0.986 mg/g content of α‐tocopherol could be achieved at 60°C in 2 h. Both of the two processes were feasible from the economic point of view for further utilisation of cottonseed. © 2011 Canadian Society for Chemical Engineering