Initial Free Fatty Acid Content Research Articles

Experimental investigation on storage of food grains using cow dung-based desiccant as preservative

ABSTRACT Food grains, produced abundantly during the harvest season, face the challenge of maintaining their quality for extended periods. While immediate consumption is an option, long-term storage offers distinct advantages by ensuring a continuous food supply beyond the harvest season. Proper storage is a critical post-harvest factor that contributes to various benefits, including economic growth and food security. In this context, this paper presents an experimental study focused on the development and evaluation of a hybrid cow dung-based desiccant (HCDD) as a potential preservative for food grains. The study thoroughly examines the impact of this innovative desiccant, HCDD, on the quality of stored rice and wheat grains. Initially, the lipid content of rice grains in C3 and C4 drums was recorded at 1.97%. However, after 8.5 months of storage, a significant decline in quality was observed in C3, where the lipid content decreased to 1.78%. In contrast, C4 maintained a stable lipid content at 1.89%. Similarly, the initial free fatty acid content in rice grains in both C3 and C4 drums was 1.78%, but after 8.5 months, C3 experienced a significant increase to 7.48%, indicating substantial deterioration. Conversely, C4 exhibited a more modest increase, reaching 4.29% over the same period. Regarding wheat quality, the initial gluten content in C1 and C2 drums was 28.12%. After 5.5 months of storage, C1 exhibited a considerable decline, with gluten content decreasing to 17.62%. In contrast, C2, utilizing HCDD, displayed a milder decrease, reaching 19.1% after 13 months. Furthermore, the initial acid value in C1 and C2 drums for wheat grains was 10.2 mg KOH/g fat. After 5.5 months, C1 experienced a substantial increase in the acid value, rising to 26.8 mg KOH/g fat, indicating grain deterioration. Conversely, C2, benefiting from HCDD, exhibited a less pronounced increase, with an acid value of 15.4 mg KOH/g fat after 13 months. This study meticulously monitored the quality of stored grains by measuring crucial parameters such as lipid content, free fatty acids in rice, gluten, and acid values in wheat. The consistent findings revealed that grains stored with HCDD exhibited superior preservation qualities. They retained lower levels of moisture and experienced significantly slower deterioration rates compared to those stored without HCDD. This not only enhances the shelf life of grains but also ensures their nutritional and qualitative integrity.

Influence of 10 MeV electron beam irradiation on the lipid stability of oat and barley during storage

This study investigated the effect of electron beam irradiation (EBI) on the lipid stability of oat and barley during long-term storage. Results showed that the initial free fatty acid content in oat was higher than that in barley. This may mean that lipid hydrolysis started under the function of lipase when oat and barley were milled into flours. Both storage and EBI factors influenced lipid-degrading enzyme activity and promoted lipid oxidation in oat and barley. However, it seemed that storage had higher impacts because the DPPH scavenging activity decreased greatly, and the contents of both malondialdehyde and volatile lipid oxidation products increased in all samples. Thus, the antioxidant capacity and level of lipid oxidation after EBI treatment should be considered when producing oat and barley foods. Overall, this study shows the high potential of EBI for use as a non-thermal technique in stabilising the storage quality of oat and barley.

Continuous double-step acid catalyzed esterification production of sludge palm oil using 3D-printed rotational hydrodynamic cavitation reactor

Sludge palm oil (SPO) with high free fatty acid (FFA) content was processed using a continuous and double-step esterification production process in a rotor-stator-type hydrodynamic cavitation reactor. Three-dimensional printed rotor was made of plastic filament and acted as a major element in minimizing the FFA content in SPO. To evaluate the reduced level of FFAs using both methods, five independent factors were varied: methanol content, sulphuric acid content (H2SO4), hole diameter, hole depth, and rotor speed. The first-step conditions for the esterification process included 60.8 vol% methanol content, 7.2 vol% H2SO4 content, 5.0 mm diameter of the hole, 6.1 mm depth of the hole, and 3000 rpm speed of the rotor. The initial free fatty acid content decreased from 89.16 wt% to 35.00 wt% by the predictive model, while 36.69 wt% FFA level and 94.4 vol% washed first-esterified oil yield were obtained from an actual experiment. In the second-step, 1.0 wt% FFA was achieved under the following conditions: 44.5 vol% methanol content, 3.0 vol% H2SO4 content, 4.6 mm hole diameter, 5.8 mm hole depth, and 3000 rpm rotor speed. The actual experiment produced 0.94 wt% FFA content and 93.9 vol% washed second-esterified oil yield. The entire process required an average electricity of 0.137 kWh/L to reduce the FFA level in the SPO below 1 wt%.

Aerobic Liquor Washing Improves the Quality of Crude Palm Oil by Reducing Free Fatty Acids and Chloride Contents

AbstractThe presence of free fatty acids (FFA) and chloride contents in crude palm oil is not desirable because they have an impact on oil quality and food safety. This work presents a method to reduce these compounds by washing the crude palm oil (CPO) with treated aerobic liquor (AL). The effects of process parameters on the reduction of FFA and chloride in CPO and the resultant 3‐monochloropropane‐1,2 diol ester (3‐MCPDE) formed after refining are investigated. The results show that the AL dosage, initial FFA content, mixing speed, and duration have significant influence on the reduction of FFA in the CPO. Meanwhile, the chloride content is reduced by approximately 50% regardless of the AL dosage used. Consequently, the 3‐MCPDE content in the oil after refining is up to 53% lower than that of the refined oil produced from the untreated CPO. Furthermore, an oil recovery above 97% can be achieved after the AL‐washing step. The implementation strategy of this method in the palm oil mills has also been proposed. In conclusion, an effective and sustainable method for in situ improvements of the quality and food safety of palm oil has been developed without the need for additional water or chemical.Practical Applications: Treated aerobic liquor can be used to wash the CPO in palm oil mill for in situ reductions of FFA and chloride contents in CPO to improve the oxidative stability of CPO. The lower content of chlorides in CPO could mitigate the formation of 3‐MCPDE during refining, thus improving the food safety of palm oil. This method can readily be implemented by the industry and it is sustainable because it does not require the use of additional process water or chemical.

Deacidification of rice bran oil using a deep eutectic solvent

The liquid-liquid extraction (LLE) will be applied in this study using a deep eutectic solvent (DES) of choline chloride and ethylene glycol with a 1:2 molar ratio. The LLE process will compare the results of removing free fatty acids (FFAs) between single and multiple extractions. Rice bran oil (RBO) with various initial FFAs contents (5%, 10%, 20%, 30%, 40%, and 60%, w/w) and γ -oryzanol (2%, w/w) are used in this study. Deacidification is carried out by mixing RBO with a certain level of FFAs and γ -oryzanol, a volume ratio of RBO: solvent (DES) = 1:2, and total extraction time in multiple LLE was 1200 min. (240 min./stage x 5 stage). It was obtained that the removal of FFAs in the single LLE are 10.04%, 23.28%, 13.43%, 17.55%, and 17.49%, respectively, while in the multiple LLE are 48.64%, 60.37%, 63.13%, 63.15%, and 41.79%, respectively, for RBO with an initial FFAs content of 5%, 10%, 20%, 30%, 40% and 60%, respectively. The losses of γ-oryzanol in the single LLE are 48.32%, 61.26%, 73.32%, 74.22%, and 89.59%, respectively, while in the multiple LLE are 87.16%, 95.58%, 99.14%, 99.77%, and 99.77%, respectively, for RBO with an initial FFAs content of 5%, 10%, 20%, 30%, 40% and 60%, respectively. Deacidification of RBO using DES in the multiple LLE removed FFAs 3.63 times higher than that in the single LLE. However, the losses of γ-oryzanol increased in the multiple LLE which is 1.43 times higher than that in the single LLE.

Use of hydrodynamic cavitation for esterification of free fatty acids in waste cooking oil

Esterification followed by transesterification process is widely applied for biodiesel production from oil with high free fatty acids (FFA) content to remove the FFA and increase the yield of biodiesel. The aim of this research was to study the esterification of waste cooking oil using the hydrodynamic cavitation apparatus. Waste cooking oil with initial FFA content 4.33% was esterified with methanol using sulfuric acid 1%-w/w as the catalyst. The reaction condition was kept constant for 120 minutes of total reaction time. At the best operating condition i.e. molar ratio of waste cooking oil to methanol 1:10 and reaction temperature 50 °C, the initial FFA of waste cooking oil 4.33% reduced to 0.76%. The experimental results also showed that the hydrodynamic cavitation had better performance than the conventional process using mechanical stirring.

Walnut oil deacidification by liquid–liquid extraction with ethanol in a single- and multistage crossflow process

Liquid–liquid extraction of vegetable oil with ethanol predominantly removes the components having the greatest affinity for ethanol, such as free fatty acids responsible for the acidity of oil, but also some contaminants such as phthalates. The aim of this work is to study the effect of several operating parameters on the deacidification process: the initial free fatty acid content in oil (3.1, 5.8, 7.6 and 11.7% OA eq.), the ethanol-water content in solvent (70.0/30.0, 80.0/20.0, 87.8/12.2 and 95.6/4.4 g/g), and the oil/solvent ratio (0.50, 0.75 and 1.00 g/g). The economic assessment of the deacidification based on the costs of distilling solvent and neutral oil loss showed that the use of solvents containing 82 to 90 wt.% of ethanol enables to achieve a trade-off between efficiency of the extraction of free fatty acid and the neutral oil losses. A three-stage crosscurrent extraction using a solvent at 88.6 wt.% of ethanol (global solvent/oil ratio: 8.0 g/g) reduced the free fatty acid content from 5.8% OA eq. (in crude walnut oil) to 0.3–0.4% OA eq. with a loss of 4.0% of neutral oil mass. Regarding the extraction of phthalates, our results showed that the lower the water content in the hydroethanolic solvent, the more efficient the extraction of butyl benzyl phthalate (BBP). Moreover, extraction with ethanol has successfully reduced the BBP content below the current regulatory limit.

Esterification of Free Fatty Acids with Glycerol within the Biodiesel Production Framework

Companies in the field of the collection and treatment of waste cooking oils (WCO) for subsequent biodiesel production usually have to cope with high acidity oils, which cannot be directly transformed into fatty acid methyl esters due to soap production. Since glycerine is the main byproduct of biodiesel production, these high acidity oils could be esterified with the glycerine surplus to transform the free fatty acids (FFA) into triglycerides before performing the transesterification. In this work, commercial glycerol was esterified with commercial fatty acids and commercial fatty acid/lampante olive oil mixtures over tin (II) chloride. In the first set of experiments, the esterification of linoleic acid with glycerol excess from 20 to 80% molar over the stoichiometric was performed. From 20% glycerol excess, there was no improvement in FFA reduction. Using 20% glycerol excess, the performance of a biochar obtained from heavy metal-contaminated plant roots was compared to that of SnCl2. Then, the effect of the initial FFA content was assessed using different oleic acid/lampante olive oil mixtures. The results illustrated that glycerolysis was impeded at initial FFA contents lower than 10%. Finally, the glycerolysis of a WCO with 9.94% FFA was assayed, without success.

An improvement study of biodiesel production from rice bran via non-catalytic in-situ transesterification using a subcritical water-methanol mixture

A non-catalytic in-situ transesterification of biodiesel production from rice bran using subcritical water-methanol mixture was found to be unaffected by initial moisture and free fatty acids (FFA) contents. The method has been known as environmentally friendly conversion since no catalyst was used. Acid catalyst has an important role in in-situ transesterification due to their ability to accelerate the oil extraction from the bran and the reaction rate. In this study, CO2 as pressurizing gas was added into subcritical water methanol mixture to increased yield and content of biodiesel. Effect of different operation pressure (P = 40-100 bar) at subcritical water methanol mixture (T = 200°C) and reaction time of 180 min on the yield and content of biodiesel were investigated. Rice bran with initial FFA content of 40.42 % has been subjected into hydrothermal reactor together with water methanol mixture to produce rice bran oil (RBO)-based biodiesel. The more CO2 as pressurizing gas was added into the hydrothermal reactor, the more yield and content of biodiesel were obtained. The highest yield and content of biodiesel of 98.00±1.41% and 83.93%, respectively, were produced under P = 100 bar.

Impact of processing on n-3 LC-PUFA in model systems enriched with microalgae

Microalgae have already shown their potential as an alternative source of n-3 LC-PUFA. In this study, 5 different microalgal species (Isochrysis, Nannochloropsis, Phaeodactylum, Porphyridium and Schizochytrium) were added to an acidic model system and screened on their potential use in acidic food matrices. The impact of mechanical and thermal processing on the model systems was studied by analyzing the amount of n-3 LC-PUFA, free fatty acids, carotenoids, lipid polymers and the oxidative stability. A (limited) reduction of n-3 LC-PUFA was observed. Thermal alterations combined with the presence of free fatty acids seemed to be the causing factor for this decrease. Furthermore, the oxidative stability of model systems enriched with photoautotrophic microalgae was significantly higher than of those enriched with heterotrophic microalgae. It can therefore be concluded that photoautotrophic microalgae low in initial free fatty acid content are a promising source of n-3 LC-PUFA in thermally processed acidic food systems.

Deacidification and ethyl biodiesel production from acid soybean oil using a strong anion exchange resin

The objective of this work was to investigate simultaneously the deacidification and the ethyl biodiesel production from soybean oil using the Amberlyst A26 OH anion exchange resin. The behavior of the process was investigated as a function of resin loading, ethanol concentration and initial free fatty acids (FFAs) content. To obtain the acidified oil, degummed soybean oil and commercial linoleic acid were mixed. The Langmuir model was able to better describe the FFAs adsorption isotherms in comparison to the Freundlich equation. A high removal of FFAs with high deacidification rate could be obtained using lower initial ratios of FFAs per mass of dry resin, being this the more favorable condition for oil deacidification. Ester formation showed to be affected by the resin loading, initial FFA content and ethanol concentration in the medium. The adsorption of FFAs seemed to deactivate the catalytic activity of the resin sites. For this reason, a high resin loading was required, although it was still possible to obtain a satisfactory biodiesel production. The present work makes possible deeper understanding of oil processing by anion exchange resins in the presence of an alcoholic solvent.

A biodiesel production process catalyzed by the leaching of alkaline metal earths in methanol: from a model oil to microalgae lipids

BACKGROUND A response surface methodology was used to study the reaction mechanism of strontium oxide (SrO) as a catalyst for a biodiesel production process using a model oil (composed of fatty acid methyl esters (FAME), free fatty acids (FFAs) and triglycerides). The influence of several factors (initial FAME content (0–30 wt%), initial FFAs content (oleic acid 0.20–2.7 wt%), temperature (40–60 °C), methanol to model oil ratio (11–43 wt%), catalyst to model oil ratio (0.5–2.5 wt%) and reaction time (5–30 min)) on the FAME yield, the FAME content, the pH of polar phase and the biodiesel alkalinity was studied. SrO was also compared with potassium hydroxide (KOH) for the conversion of Scenedesmus Obliquus microalgae esterified lipids after a first step of FFAs esterification with sulfuric acid into biodiesel with the following conditions: temperature: 60 °C; reaction time: 22.2 min; catalyst to microalgae ratio: 2.48 wt%; methanol to microalgae lipid ratio: 31.4 wt%. RESULTS With those operating conditions, KOH was able to reach a slightly higher FAME yield (32.6% g FAME g−1 lipid) than SrO (29.0% g FAME g−1 lipid). Moreover, the results showed a strong relationship between the pH of the polar phase (glycerol–methanol–water) and the FAME yield, which indicates that the reaction using alkaline metal earths is mostly catalyzed by a homogeneous reaction. CONCLUSION The fact that alkaline metal earths act as homogeneous catalysts make them less suitable for biodiesel production, because they are not inducing neutral pH, and they increase the risk of corrosion. © 2016 Society of Chemical Industry

Adsorptive Removal of Saturated and Unsaturated Fatty Acids Using Ion-Exchange Resins

One of the pretreatment approaches for decreasing the initial acid content of waste vegetable oil or nonedible oils with high initial free fatty acid content, with an objective of obtaining a suitable starting raw material for the production of biodiesel, is the adsorption of the free acids using ion-exchange resins. The present work deals with investigation of adsorption characteristics of saturated (stearic) and unsaturated (oleic) fatty acids on different ion exchange resins (polymeric strong (Indion 810) and weak (Indion 850 and Indion 860) anion exchange resins). The ion exchange resins contain tertiary or quaternary amino functional groups on the styrene-divinyl benzene copolymer matrix which can facilitate the adsorption of acids. Kinetic adsorption studies have been carried out initially to determine the contact time required to reach the adsorption equilibrium between fatty acid adsorbed on the resin and remaining fatty acid present in the oil. Equilibrium adsorption studies have been carried out...

The influence of free fatty acid intermediate on biodiesel production from soybean oil by whole cell biocatalyst

Abstract The whole cell of lipase-producing Rhizopus oryzae was employed as biocatalyst for transesterification of soybean oil containing oleic acid. The free fatty acid (FFA) intermediate, playing an important role in the kinetics of transesterification of soybean oil, was thoroughly investigated and characterized. The conversion was more than 97% at the initial FFA content of 5.5%. A high content of FFA could protect the lipase from denaturation. The 34.6 percent of FFA with the optimal 26-mg mL −1 methanol resulted in a specific reaction rate of 420 mg h −1 g-dry cell −1 . In addition, the methanol/FFA ratio at 0.83–1.7 provides a good indication of the fatty acid methyl esters conversions for different initial FFA contents. In the transesterification process, more FFA intermediate present would become beneficial to conversion of retrograde feedstock to biodiesel. The immediately generated and original FFA content become the major rate-determining factor in the FFA-mixed transesterification process.

H2SO4/CaO-Catalyzed Process for Biodiesel Production from High Acid Value Jatropha curcas Crude Oil

Transesterification is affected by the free fatty acid (FFA) content of vegetable oils or animal fats. A two-step H2SO4/CaO-catalyzed methanolysis process has been employed for the efficient conversion of Jatropha curcas crude oil, which has an acid value greater than 30 mg KOH/g, into fatty acid methyl ester (FAME). The effects of H2SO4 catalyst addition, of FFA, and of the water produced as a by-product are investigated. The maximum esterification activity of the initial FFA content are obtained with 0.5–1.2 wt% H2SO4 relative to Jatropha crude oil. The esterification product is used as the substrate for a second, CaO-catalyzed, transesterification. Water usually has an adverse effect on transesterification; however, this study proves that the effect of water is negligible. Using this two-step methanolysis reaction, a FAME level greater than 96% can be obtained in the final product.

Simultaneous Conversion of Triglyceride/Free Fatty Acid Mixtures into Biodiesel Using Sulfated Zirconia

Simultaneous transesterification and esterification of rapeseed oil with methanol in the presence of myristic acid was investigated. The effect of reaction temperature (120, 150 and 170 °C) and the effect of initial free fatty acid content in oil (0, 10 and 20 wt%) on reaction rate were studied. The catalysts were found to increase the rate of all reactions. Sulfated zirconia prepared by a solvent-free method exhibited higher activity in simultaneous reaction than the conventional method. The presence of 10 wt% free fatty acids in the triglyceride increased the reaction rate and the final total fatty acid methyl esters content, and suggests that a “non-catalytic” reaction may be feasible.

Biodiesel production from rice bran by a two-step in-situ process

The production of fatty acid methyl esters (FAMEs) by a two-step in-situ transesterification from two kinds of rice bran was investigated in this study. The method included an in-situ acid-catalyzed esterification followed by an in-situ base-catalyzed transesterification. Free fatty acids (FFAs) level was reduced to less than 1% for both rice bran A (initial FFAs content = 3%) and rice bran B (initial FFAs content = 30%) in the first step under the following conditions: 10 g rice bran, methanol to rice bran ratio 15 mL/g, H 2SO 4 to rice bran mass ratio 0.18, 60 °C reaction temperature, 600 rpm stirring rate, 15 min reaction time. The organic phase of the first step product was collected and subjected to a second step reaction by adding 8 mL of 5 N NaOH solution and allowing to react for 60 and 30 min for rice bran A and rice bran B, respectively. FAMEs yields of 96.8% and 97.4% were obtained for rice bran A and rice bran B, respectively, after this two-step in-situ reaction.

A new hypothesis about continuous distillation with striping gas and its application the physical refining of edible oils

The influence of the free fatty acid concentration in the gas inside the continuous deodorizer in continuous physical refining was studied and a hypothesis was formed to explain the results: In a continuous process of deacidification by distillation of free fatty acids at low pressure (2 - 3 mbar), high temperature (180 – 260 oC), with stripping gas, initial free fatty acid content of oil ≤ 7.4% w/w and similar temperature for both the gas distillate inside the continuous deodorizer and the oil, in the equilibrium the ratio between the free fatty acid content of the deacidified oil and the concentration of free fatty acids in the gas inside the continuous deodorizer is constant. This hypothesis is submitted to discussion.

Isolation of oryzanol from crude rice bran oil

The isolation of oryzanol from crude rice bran oil (RBO) was achieved by a two-step crystallization process. In the first crystallization, oryzanol was concentrated in the liquid phase along with free fatty acid (FFA), monoacylglycerol (MG), squalene, tocols, and phytosterols, whereas the solid phase contained mainly triacylglycerol (TG) and steryl esters. Oryzanol-rich product obtained from the first crystallization was subjected to the second crystallization where the oryzanol-rich product was kept at room temperature (20.5 ± 1.5 °C) for 24 h. Hexane was added as anti-solvent to the oryzanol-rich product and kept at 5 ± 1 °C for another 48 h. Parameters that affect the isolation of oryzanol from crude RBO were systematically investigated. Under optimal operation conditions, oryzanol with purity and recovery of 93-95% and 59%, respectively, was obtained from RBO with an initial FFA content of ca . 5%.

Temperature Effects on the Deacidification of Mixtures of Sunflower Oil and Oleic Acid

AbstractAlthough it is well known that oil temperature is an essential factor for determining the deacidification mass rate and the final free fatty acids content, the influence of the temperature of the gas distillates above the liquid phase in the deodorizer on the oil temperature is much less understood. An extensive study of the effect of the temperature of the oil and of the gas distillates was undertaken in a continuous deodorizer, comparing the results with those obtained using a batch process. Variations in temperature from the temperature obtained without additional heating of the gases to a higher temperature than that of the oil were assayed for the gas distillates at the head of the deodorizer. It was possible to obtain low outlet free fatty acid contents at lower oil temperatures by controlling the overheating of the distillates, even for very high initial free fatty acids content, indicating that this is an essential variable to consider in distillation. However, increasing the temperature of the gas distillates above that of the oil sometimes produces a negative effect in deacidification.