Economic analysis of two processes for biodiesel production

In this study, two continuous processes for biodiesel production, alkali catalyzed process and solid acid catalyzed process, are discussed with the help of Aspen Plus. By comparing some economic indicators, it can be found that solid acid catalysis could be a good choice for investors in the near future.     

Theoretical Study on Free Fatty Acid Elimination Mechanism for Waste Cooking Oils to Biodiesel over Acid Catalyst

A theoretical investigation on the esterification mechanism of free fatty acid (FFA) in waste cooking oils (WCOs) has been carried out using DMol³ module based on the density functional theory (DFT). Three potential pathways of FFA esterification reaction are designed to achieve the formation of fatty acid methyl ester (FAME), and calculated results show that the energy barrier can be efficiently reduced from 88.597 kcal/mol to 15.318 kcal/mol by acid catalyst. The molar enthalpy changes (Δ_rH_m°) of designed pathways are negative, indicating that FFA esterification reaction is an exothermic process. The obtained favorable energy pathway is: H⁺ firstly activates FFA, then the intermediate combines with methanol to form a tetrahedral structure, and finally, producing FAME after removing a water molecule. The rate-determining step is the combination of the activated FFA with methanol, and the activation energy is about 11.513 kcal/mol at 298.15 K. Our results should provide basic and reliable theoretical data for further understanding the elimination mechanism of FFA over acid catalyst in the conversion of WCOs to biodiesel products.     

Structural/texture evolution of CaO/MCM‐41 nanocatalyst by doping various amounts of cerium for active and stable catalyst: Biodiesel production from waste vegetable cooking oil

In present work, the aim of producing biodiesel from waste cooking oil was pursued by doping the cerium element into the MCM‐41 framework as catalyst with various Si/Ce molar ratio (5, 10, 25, 50, and Ce = 0). The catalytic performance and stability improved by employing the ultrasound irradiation in active phase loading step of catalyst preparation. The physicochemical characteristics of synthesized samples were investigated using various techniques as follows: Brunauer‐Emmett‐Teller (BET), X‐ray powder diffraction (XRD), Fourier transfer infrared (FTIR), energy‐dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM). The XRD patterns along with the results of FTIR and BET analysis revealed the MCM‐41 framework destruction while increasing the Ce content. The FESEM images of the nanocatalysts illustrated a well distribution and uniform morphology for the Ca/CeM (Si/Ce = 25). The particle size and size distribution of the Ca/CeM (Si/Ce = 25) were subsequently determined by TEM and FESEM images. The activity of fabricated nanocatalysts was evaluated by measuring the free acid methyl ester (FAME) content of produced biodiesel. The tests were carried out at constant operational conditions: T = 60°C, catalyst loading = 5 wt%, methanol/oil molar ratio = 9, and 6‐hour reaction time. A superior activity was observed for Ca/CeM (Si/Ce = 25) among other nanocatalysts with 96.8% conversion of triglycerides to biodiesel. The mentioned sample was utilized in five reaction cycles, and at the end of the fifth cycle, the conversion reached to 91.5% which demonstrated its significant stability.     

Extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins: part I – Effect of moisture content

This study investigated the effects of moisture content (MC) on the physicochemical properties of extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins. Samples were extruded at 170 °C (maximum barrel temperature), at 3.6 kg h⁻¹ (liquid feed rate) and at 1.8, 2.2, 2.6 and 3.0 kg h⁻¹ (dry feed rates) to obtain MC of 60%MC, 56%MC, 52%MC and 49%MC, respectively. Meat alternatives at 52%MC showed the greatest degree of texturisation. However, meat alternatives at 49%MC were the closest in terms of both textural and microstructural properties to reference sample, boiled chicken breast. Results from protein solubility suggested that a large amount of aggregated proteins were associated with hydrogen bonds, while disulphide bonds were the main contributor in the formation of fibrous structure in meat alternatives. Results showed that the change in MC as process parameter played an important role in the formation of fibrous structure in extruded meat alternatives.     

Influence of bunch maturation and chemical precursors on acrylamide formation in starchy banana chips

The present study investigated the effect of ripening stages and chemical precursors on acrylamide formation in deep-fried chips of five plantains and one cooking banana. The highest level of acrylamide was found in the cooking banana, followed by False Horn plantain and French plantain, respectively. French plantain hybrids exhibited a significantly lower (P < 0.05) level of acrylamide when compared to French plantain. The ripening stage demonstrated a positive Pearson correlation (P < 0.05, r = 0.57) with acrylamide formation. As ripening progressed, the levels of glucose and fructose significantly increased (P < 0.05) and showed a positive correlation with acrylamide formation (r = 0.85 and 0.96, respectively). The level of the amino acid asparagine during ripening was not correlated with acrylamide formation. In contrast, the level of histidine, arginine, iso-leucine and cystine during ripening was positively correlated (P < 0.05, r > 0.60) with acrylamide formation in fried chips. The higher level of TP was significantly related (P < 0.05) to the lower level of acrylamide (r = −0.62). The reduced levels of carotenoid isomers, except lutein, during fruit ripening were positively correlated (P < 0.05) with acrylamide formation, especially trans-BC (r = 0.72) and 9-cis-BC(r = 0.64).     

Model-based multi-objective optimization of beef roasting

A validated mathematical model has been used to perform multi-objective optimization of beef roasting, considering the minimization of both cooking time and weight loss. Simulations were performed using irregular geometrics models of beef semitendinosus muscle and constant oven temperature. Minimum temperature of 72 °C at the coldest point was imposed as a constraint. From model results a compromise situation was encountered, since no operative condition lead simultaneously to optimal values of both objectives, i.e., an increase in oven temperature leads to a decrease in cooking time, between −0.25 and −0.325 min/°C, and an increase in weight loss, between 0.175 and 0.275%/°C. In this sense, not one, but a set of optimal solutions was found in the Pareto sense. Experimental cooking tests were performed, which are in good agreement with model simulations. Furthermore, energy consumption for each optimal solution obtained in the optimization problem was estimated, being lower using low oven temperatures.     

Numerical investigation of the flow inside the combustion chamber of a plant oil stove

Recently a low cost cooking device for developing and emerging countries was developed at KIT in cooperation with the company Bosch und Siemens Hausger te GmbH.After constructing an innovative basic design further development was required.Numerical investigations were conducted in order to investigate the flow inside the combustion chamber of the stove under variation of different geometrical parameters.Beyond the performance improvement a further reason of the investigations was to rate the effects of manufacturing tolerance problems.In this paper the numerical investigation of a plant oil stove by means of RANS simulation will be presented.In order to reduce the computational costs different model reduction steps were necessary.The simulation results of the basic configuration compare very well with experimental measurements and problematic behaviors of the actual stove design could be explained by the investigation.     

Polymeric protein formation during pasta-making with barley and semolina mixtures,and prediction of its effect on cooking behaviour and acceptability

Spaghetti were produced in a pilot plant from semolina and semolina blended with increasing amounts of barley flour. According to size exclusion high-performance liquid chromatography (SE-HPLC), barley proteins interact with semolina proteins during pasta making, forming polymers of high molecular weight. Of these, the unextractable polymeric proteins (UPP) were at significantly higher concentrations than in spaghetti made from semolina. The decrease of both S–S bonds and –SH free groups in barley semolina spaghetti, with respect to that made of semolina, suggested that polymerisation among the different classes of proteins involves a new bonding arrangement. Due to β-glucan hydrophilicity and competition with starch for water, the replacement of increasing amounts of semolina with barley flour was able to increase the optimal cooking time. The sensory properties of composite spaghetti were judged as better than the control because of the higher firmness and the lower bulkiness and stickiness of the former.