Acid-Catalyzed Homogeneous Esterification Reaction for Biodiesel Production from Palm Fatty Acids

This work deals with esterification of palm fatty acids to produce biodiesel in a batch reactor, using homogeneous acid catalysts, evaluating the effect of the alcohol used, presence of water, type and concentration of catalysts. Methanesulfonic and sulfuric acid were the best catalysts. Reaction with methanol showed greater yields. It was showed very clearly that the presence of water in the reaction medium showed a negative effect in the reaction velocity. Kinetic parameters were estimated and molecular modeling was performed. Protonation of the carboxylic moiety of the fatty acid were defined as rate determinant step for the reaction.     

Titanium–Silica Catalysts for the Production of Fully Epoxidised Fatty Acid Methyl Esters

Grafted titanium-containing mesoporous silica catalysts were used in the selective epoxidation of C-18 unsaturated fatty acid methyl esters (FAMEs). High yields in mono- and diepoxide derivatives were obtained under acid-free reaction conditions with TBHP as oxidant. Ti-MCM-41 showed the best performance in terms of activity over the three FAMEs. Easy separation of the desired products and recycling of the catalyst were demonstrated.     

Supplemental dietary flaxseed oil affects both neutral and phospholipid fatty acids in cultured tilapia

This work aimed to evaluate the neutral lipid (NL) and phospholipid (PL) classes in tilapia (Oreochromis niloticus) muscle tissue. Tilapias were raised in captivity for a period of 5 months with increasing levels (0, 1.25, 2.50, 3.75, and 5.00%) of flaxseed oil [source of α‐linolenic acid (LNA), 18:3n‐3] in substitution for sunflower oil (control). The NL/PL ratio was 1.9, and 45 fatty acids were determined for both classes of lipid. The class totals of n‐3 acids always increased in all treatments, while the totals for n‐6 acids always decreased (p <0.05). For a given level of flaxseed oil, the LNA contents were consistently higher, including EPA (20:5n‐3) and DHA (22:6n‐3). Arachidonic acid (20:4n‐6) remained high in the PL but was reduced as levels of dietary flaxseed oil were increased. The n‐6/n‐3 ratios decreased significantly with the rise in flaxseed oil content in all treatments, and highly unsaturated fatty acid contents increased with the levels of flaxseed oil. Overall, the influence of flaxseed oil on the fatty acid composition in the contributing NL and PL classes was to increase n‐3 PUFA, thus raising the nutritional value of this freshwater fish meat and, consequently, contributing to the health of consumers.     

Solid‐phase extraction in combination with GC/MS for the quantification of free fatty acids in adipocere

Current research investigating the effect of specific aquatic microenvironments on the formation of adipocere using domesticated pigs (Sus scrofa) has demonstrated the need for a fast and reliable method to separate and identify fatty acids present in adipocere. Adipocere is defined as a late‐stage post‐mortem decomposition product consisting of a mixture of free fatty acids (FFA), which have formed under favorable conditions due to the hydrolysis of triglycerides in adipose tissue. Whilst good separations of adipocere lipids have been achieved using TLC, this method is time consuming when processing large numbers of samples. This paper describes a rapid and simple method for the extraction, identification and quantification of FFA commonly found in adipocere, by solid‐phase extraction (SPE) using aminopropyl disposable columns in combination with GC/MS. The recoveries of FFA associated with adipocere were all above 90%, with coefficients of variation below 10%, indicating that the technique was reproducible. The limits of quantification were registered at levels of parts per million. Standard curves were linear over the range of 50–1000 µg/mL, with all correlation coefficient values greater than 0.998. A marked increase in concentration of saturated fatty acids was observed during adipocere formation, ranging from 20 to 55% for palmitic acid, 13 to 23% for stearic acid and 2.8 to 4.1% for myristic acid. These results demonstrate the suitability of aminopropyl disposable SPE columns to efficiently and rapidly isolate FFA from adipocere prior to quantitative GC/MS analysis.     

Fatty acid fouling of reverse osmosis membranes: implications for wastewater reclamation

Effluent organic matter (EfOM) contributes significantly to organic fouling of reverse osmosis (RO) membranes in advanced wastewater reclamation. In this study, the effect of feed solution chemistry (solution pH and Ca²⁺ concentration) on the fouling of RO membranes by octanoic acid—selected to represent fatty acids in EfOM—is investigated. Crossflow fouling experiments demonstrate that RO membrane fouling is much more significant at solution pH below the pK_a of the octanoic acid (pK_a = 4.9) than at an elevated pH. Octanoic acid permeates across the membranes more readily at solution pH below its pK_a than at elevated pH. At pH below the octanoic acid pK_a, fouling behavior is not affected by calcium ions, whereas at elevated pH, the rate of flux decline decreases with higher calcium ion concentration. The effect of calcium on the fouling behavior was further verified from foulant-foulant adhesion forces, determined by atomic force microscopy (AFM) force measurements under solution chemistries identical to those of the crossflow fouling experiments. To investigate the implications of octanoic acid fouling for wastewater reclamation, the effect of octanoic acid on membrane fouling by a combination of organic foulants in the presence of calcium ions is studied. At a solution chemistry simulating that of typical wastewater effluents, the addition of octanoic acid to a feed solution containing alginate, bovine serum albumin, and Suwannee River natural organic matter, does not enhance membrane fouling behavior. This observation could be attributed to the significant contribution of the alginate-calcium complexes within the fouling layer to the total membrane resistance.     

Scale-up of anaerobic digestion of the biowaste fraction from domestic wastes

In the City of Karlsruhe/Germany anaerobic digestion of 7200 ta(-1) of separately collected biowaste has proven its feasibility at an organic loading rate (OLR) of up to 8.5 kg CODm(-3)d(-1). An extension of biowaste collection over the whole city area would increase the amount of biowaste to 12,000 ta(-1), leading to an OLR of the existing anaerobic reactor of up to 15 kg CODm(-3)d(-1). To test, whether the increased amount of biowaste could be stabilized in the existing plant, biowaste suspensions were digested in a laboratory reactor at a maximum OLR, that exceeded the future OLR of the full-scale plant.The laboratory reactor was started with effluent of the full-scale biowaste digester. Like in full-scale, biowaste suspension from the hydropulper was added in a fed-batch mode. The elimination of organic material (measured as COD, chemical oxygen demand) and the volumetric gas production were linearly increasing with the OLR from 4.3 to 19 kg CODm(-3)d(-1). Thus, safe operation of the full-scale plant at an OLR of 15 kg CODm(-3)d(-1) should be possible, leaving still some reserve capacity.To determine the metabolic reserves for fatty acid degradation during digestion at an OLR of 10 kg CODm(-3)d(-1), digester effluent was supplemented with either 40 mmoll(-1) acetate, propionate, i-butyrate or n-butyrate. Results of these batch assays indicated a rapid degradation of all fatty acids and fatty acid conversion rates, that would allow a stable anaerobic fermentation at 15 kg CODm(-3)d(-1)OLR.On the basis of the laboratory results the OLR of the full-scale methane reactor was increased to 15 kg CODm(-3)d(-1). After 7 months, results of full-scale digestion were still consistent with the previously obtained laboratory results.     

Physico-Chemical Characteristics of Citrus Seeds and Seed Oils from Pakistan

The physico-chemical characteristics of the seeds and seed oils of four citrus species, Mitha (Citrus limetta), Grapefruit (Citrus paradisi), Mussami (Citrus sinensis), and Kinnow (Citrus reticulata) were investigated. The hexane-extracted oil content of citrus seeds ranged from 27.0 to 36.5%. The protein, fiber and ash contents were found to be 3.9–9.6%, 5.0–8.5%, and 4.6–5.6%, respectively. The extracted oils exhibited an iodine value of 99.9–110.0; refractive index (40 °C), 1.4639–1.4670; density (24 °C), 0.920–0.941 mg/mL; saponification value, 180.9–198.9; unsaponifiable matter, 0.3–0.5%; acid value (mg KOH/g of oil), 0.5–2.2 and color (1-in. cell) 1.4–3.0R + 15.0–30.0Y. The oils revealed a good oxidative stability as indicated by the determinations of specific extinctions at 232 and 270 nm (2.3–4.4 and 0.6–0.9, respectively), p-anisidine value (2.2–3.2) and peroxide value (1.6–2.4 mequiv/kg of oil). The citrus seed oils mainly consisted of linoleic acid (36.1–39.8%). Other prominent fatty acids were palmitic acid (25.8–32.2%), oleic acid (21.9–24.1%), linolenic acid (3.4–4.4%), and stearic acid (2.8–4.4%). The contents of tocopherols (α, γ, and δ) in the oil were 26.4–557.8, 27.7–84.1, and 9.1–20.0 mg/kg, respectively. The results of the present study demonstrated that the seeds of citrus species investigated are a potential source of valuable oil which might be utilized for edible and other industrial applications.     

Determination of the Fatty Acid Composition of Acorn (Quercus), Pistacia lentiscus Seeds Growing in Algeria

The fruits of two plants from Algeria (Quercus and Pistacia lentiscus) were investigated. The paper reports the chemical characteristics and the fatty acid composition of the oil extracts from the fruits. The black fruits of P. lentiscus has the highest crude fat of 32.8%, followed by the red fruits with 11.7%, and the lowest value of 9% in Quercus (acorn). The acid value was highest in red fruits of P. lentiscus oil (24.0 mg KOH/g), followed by the black fruits oil and lowest in acorn oil. The relatively high iodine value in the oils indicates the presence of many unsaturated bonds. Saponification value was highest in the Quercus ilex oil (166.7 mg KOH/g), while the lowest value was in the black fruits of P. lentiscus oil. Gas-liquid chromatography revealed that the three dominant fatty acids found are: palmitic C16:0 (16.3–19.5%), oleic C18:1 (55.3–64.9%), linoleic C18:2 (17.6–28.4%). The oils contain an appreciable amount of unsaturated fatty acids (78.8–83.5%).     

From Aquatic to Terrestrial Food Webs: Decrease of the Docosahexaenoic Acid/Linoleic Acid Ratio

Fatty acid composition of the adipose tissue of six carnivorous mammalian species (European otter Lutra lutra, American mink Mustela vison, European Mink Mustela lutreola, European polecat Mustela putorius, stone marten Martes foina and European wild cat Felis silvestris) was studied. These species forage to differing degrees in aquatic and terrestrial food webs. Fatty acid analysis revealed significant differences in polyunsaturated fatty acid composition between species. More specifically, our results underline a gradual significant decrease in the docosahexaenoic acid (DHA)/linoleic acid (LNA) ratio of carnivore species as their dependence on aquatic food webs decreases. In conclusion, the use of the DHA/LNA ratio in long-term studies is proposed as a potential proxy of changes in foraging behaviour of semi-aquatic mammals.