Free Ester Research Articles

Effect of 1-methylcyclopropene on flat peach fruit quality based on electronic senses, LC-MS, and HS-SPME-GC-MS during shelf storage

The effects of 1-methylcyclopropene (1-MCP) on the sensory quality of the 'Yulu' flat peach fruit were determined using electronic tongue, electronic nose, LC-MS/MS, and HS-SPME-GC-MS. A total of 90 taste compounds and 49 volatile compounds were quantified. Of these, 15–21 types of aroma compounds with odor activity values (OAV) > 1 were considered as the most significant volatiles. 1-MCP significantly affected the levels of soluble sugars, organic acids, free amino acids, phenolics, amygdalin, and volatile compounds. 1-MCP slowed the increase in alanine and γ-aminobutyric acid in fruit during ripening and senescence. 1-MCP also increased the level of proline in fruits, and decreased that of glutamic acid, glutamine, and serine. 1-MCP significantly inhibited the decline in procyanidins after six to ten days of storage. During fruit senescence, the level of free esters markedly increased; however, 1-MCP reduced this level. Fruits treated with 1-MCP contained more β-myrcene and linalool and fewer lactones. β-Damascenone, (E)-2-nonenal, (E)-2-hexenal, γ-decalactone had the highest OAVs. The PCA biplot revealed that fruit shelf-life duration had a greater effect on taste than 1-MCP, while 1-MCP had a greater impact on aroma. Our findings provide a basis for the use of 1-MCP to preserve flat peaches in the future.

Physiochemical analysis of oil extracted from Vitelleria paradoxa seed obtained from Wukari North Eastern Nigeria

Soxhlet extraction of oil from seeds of Vitelleria paradoxa was carried out using n-hexane as the solvent. Standards methods were adopted in the analysis of the physiochemical properties; moisture content, melting point, total ash content, pH, specific gravity, iodine value, saponification value, acid value, free fatty acid value and ester value were all evaluated. The oil recovery rate was good with 32.6% yield, moisture content of 3.1%, melting point of 52oC and pH 5.7. Total ash content was 50.3%, specific gravity of 0.9 g/cm3, iodine value 39 mg/L, saponification value 224.6 mgKOH/g, acid value 59.9 mgKOH/g free fatty acid (FFA) 29.9 mgKOH/L and ester value 164.7 mg/L. The results shows that oil from Vitelleria paradoxa seed holds the potentials for wider applications in foods, cosmetics, pharmaceuticals, lubricants and soap making.

Characterization of soluble sugars, glycosidically bound and free volatiles in fresh-cut pineapple stored at different temperature

Glycosidically bound volatiles are important precursors of overall aromas in fresh-cut fruit and this bound volatile can be deglycosylated to free forms by the catalyzation of β-glucosidase. The profiles of sugars, free and bound volatiles of fresh-cut pineapple subjected to 4 °;C and 20 °C were investigated. Results showed that cutting induced the increase of total sugars and sucrose in fresh-cut pineapple compared with whole pineapple, but contents of total sugar and sucrose decreased along with the storage. Cutting promoted the increase of most free esters, aldehydes, ketones and lactones at 1 d. Correspondingly, most esters, aldehydes, ketones and lactones in bound from were decreased by cutting with the induction of β-glucosidase. Besides, most free volatiles exhibited increased trends at 1 d and then decreased afterwards. Most bound volatiles exhibited decreased trends during the storage. Furthermore, in 20 °C stored fresh-cut pineapple, most free esters decreased sharply during 4 d storage, and odor flavors became the most abundant aromas, like isoamyl acetate, ethyl decanoate, ethyl octanoate, ethyl acetate, and ethanol. A total of 14 volatiles were identified in free and bound forms, and cutting inhibited the accumulations of these bound volatiles but boosted the emissions of these free volatiles, correspondingly.

Lipid profiling suggests species specificity and minimal seasonal variation in Pacific Green and Hawksbill Turtle plasma.

In this study, we applied multiple reaction monitoring (MRM)-profiling to explore the relative ion intensity of lipid classes in plasma samples from sea turtles in order to profile lipids relevant to sea turtle physiology and investigate how dynamic ocean environments affect these profiles. We collected plasma samples from foraging green (Chelonia mydas, n = 28) and hawksbill (Eretmochelys imbricata, n = 16) turtles live captured in North Pacific Costa Rica in 2017. From these samples, we identified 623 MRMs belonging to 10 lipid classes (sphingomyelin, phosphatidylcholine, free fatty acid, cholesteryl ester, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine, ceramide, and triacylglyceride) and one metabolite group (acyl-carnitine) present in sea turtle plasma. The relative ion intensities of most lipids (80%) were consistent between species, across seasons, and were not correlated to body size or estimated sex. Of the differences we observed, the most pronounced was the differences in relative ion intensity between species. We identified 123 lipids that had species-specific relative ion intensities. While some of this variability is likely due to green and hawksbill turtles consuming different food items, we found indications of a phylogenetic component as well. Of these, we identified 47 lipids that varied by season, most belonging to the structural phospholipid classes. Overall, more lipids (n = 39) had higher relative ion intensity in the upwelling (colder) season compared to the non-upwelling season (n = 8). Further, we found more variability in hawksbill turtles than green turtles. Here, we provide the framework in which to apply future lipid profiling in the assessment of health, physiology, and behavior in endangered sea turtles.

Evolution of volatile profile and aroma potential of 'Gold Finger' table grapes during berry ripening.

'Gold Finger' is a grape cultivar with a finger-like shape and a milk flavor. The process by which its aroma profile evolves during ripening is unclear. Thus, changes in the free and bound volatile compounds present in 'Gold Finger' grapes during ripening were investigated using headspace sampling-solid-phase microextraction-gas chromatography-mass spectroscopy (HS-SPME-GC-MS). A total of 83 volatile aroma components were identified in the grapes, with aldehydes, esters, acids, and alcohols being the main components. The total aroma compound content exhibited significant differences between the bound and free forms. The total content of bound volatile compounds did not change significantly during fruit development, although the free aroma compound content was significantly higher than the bound content. The total content of free aldehydes, free alcohols, bound norisoprenoids, and ketones gradually increased for up to 70 days after flowering (DAF), while the total free ester, terpene, and acid content decreased. The characteristic aroma compounds of 'Gold Finger' grapes were identified as hexanal, (E)-2-hexenal, and ethyl hexanoate. These results give a foundation for the further development of 'Gold Finger' grapes and provide a theoretical basis for the selection and breeding of novel aromatic grape varieties. © 2021 Society of Chemical Industry.

Bioactive Sugarcane Lipids in a Circular Economy Context.

Most of the global sugar and ethanol supply trade comes from the harvesting of Saccharum officinarum (i.e., sugarcane). Its industrial processing results in numerous by-products and waste streams, such as tops, straw, filter cake, molasses and bagasse. The recovery of lipids (i.e., octacosanol, phytosterols, long-chain aldehydes and triterpenoids) from these residues is an excellent starting point for the development of new products for various application fields, such as health and well-being, representing an important feature of the circular economy. By selecting green scalable extraction procedures, industry can reduce its environmental impact. Refluxed ethanol extraction methods have been demonstrated to meet these characteristics. On the other hand, effective non-solvent methodologies such as molecular distillation and supercritical CO2 extraction can fractionate lipids based on high temperature and pressure application with similar yields. Sugarcane lipophilic extracts are usually analyzed through gas chromatography (GC) and liquid chromatography (LC) techniques. In many cases, the identification of such compounds involves the development of high-temperature GC–MS/FID techniques. On the other hand, for the identification and quantification of thermolabile lipids, LC–MS techniques are suitable for the separation and identification of major lipid classes. Generically, its composition includes terpenes, phytosterols, tocopherol, free fatty acids, fatty alcohols, wax esters, triglycerides, diglycerides and monoglycerides. These compounds are already known for their interesting application in various fields such as pharma and cosmetics due to their anti-hypercholesterolemic, anti-hyperglycemic, antioxidant and anti-inflammatory properties.

Odorant degrading carboxylesterases modulate foraging and mating behaviors of Grapholita molesta

Odorant degrading carboxylesterases (CXEs) play key roles in the process of odor signal reception via degrading ester odorants. But the functional mechanisms of CXEs in modulating insect behaviors are unclear. Herein, we studied the roles that CXEs played in mating, foraging, and signal receptions of sex pheromones and host volatiles in Grapholita molesta. As a result, 23 candidate CXEs were identified by transcriptome analysis of G. molesta. The GmolCXE1 and 5 highly expressed in the antennae of male moths and GmolCXE14 and 21 abundantly expressed in larval heads, were significantly upregulated after exposure with odors from female adults or fresh ripe fruits respectively. After knockdown of GmolCXE1 and 5, or GmolCXE14 and 21 by RNA interference, the behavioral responses of G. molesta to ester sex pheromones or host volatiles were decreased, by exhibiting an inhibited searching behavior of G. molesta for females or fruits, respectively. Then evidence form GC-MS analysis, showed that the protein GmolCXE1 and GmolCXE5 could metabolize the sex pheromone components (Z/E)-8-dodecenyl acetate to their metabolites products (Z/E)-8-dodecenol, and that GmolCXE14 and GmolCXE21 could metabolize ethyl butanoate and ethyl hexanoate of ripe pears. In addition, fluorescent binding assays verified that GmolCXEs could degrade the free ester odor molecules, but not degrade the odor molecules protected by odorant-binding proteins. Our study not only demonstrated CXEs modulated the mating and foraging behaviors of G. molesta through inactivation of ester sex pheromone and host volatiles, but also discovered great potential molecular targets to develop behavioral inhibitors for pest management.

Carbonyl stretch of CH⋯O hydrogen-bonded methyl acetate in supercritical trifluoromethane.

Infrared spectroscopy in the gas phase was used to study the formation reaction of the CH⋯O hydrogen bonding complex involving the CH group of trifluoromethane, as a hydrogen donor, and the carbonyl group of methyl acetate, as a hydrogen acceptor, under different (T, p) conditions. The hydrogen-bonded carbonyl stretch of the molecular pair was monitored in dilute mixtures of methyl acetate in trifluoromethane at near-critical temperatures, from gas- to liquid-like densities. In the gas region, it was possible to discriminate the carbonyl signal of the hydrogen-bonded complex from that of the free ester and have access to their relative concentration. The equilibrium constant of the hydrogen bonding reaction and the standard enthalpy and entropy changes in the process were determined using the spectroscopic data. CH⋯O bonding was favored by lowering temperature or pressurizing F3CH in the mixture, remaining essentially no free carbonyl groups about the critical density. The carbonyl band of the hydrogen-bonded pair appeared as a single symmetric peak up to liquid-like densities, suggesting that the 1:1 methyl acetate-trifluoromethane complex has the most abundant stoichiometry. Spectral features as frequency shift and bandwidth of the hydrogen-bonded carbonyl were studied as a function of temperature and solvent-density. A bathochromic (red) vibrational shift was registered for the bound carbonyl band against density, with a sudden change in behavior in the near-critical region, while the width of this band remains mostly unresponsive.

THE EFFECT OF N-STEAROYLETHANOLAMINE ON THE ADIPOCYTE FATTY ACID COMPOSITION OF DIFFERENT AGE RATS WITH OBESITY-INDUCED INSULIN RESISTANCE

Chronic hypernutrition and high fat diet (HFD), rich in saturated fatty acids leads to molecular changes in insulin sensitive tissues and is followed by dyslipidemia. That is why the aim of our study was to investigate the fatty acid (FA) composition of phospholipids (PL), free fatty acids (FFA), triacylglycerol (TAG) and cholesterol esters (CE) of adipocytes in different age rats with HFD-induced insulin resistance (IR) and its changes under N-stearoylethanolamine (NSE) administration. The experimental model was induced on rats in age 10-month-old and 24-month-old by 6-month HFD and confirmed by the oral glucose tolerance test. NSE was administrated as water suspension per os in a dosage 50 mg/kg daily during 2 weeks. Adipocytes were isolated from abdominal fat using Type 1 Collagenase solution. Adipocytes lipid extract was separated on the fractions by thin-layer chromatography. The fatty acid composition of lipid fractions was analyzed by gas-liquid chromatography. Experimental data were processed statistically using Student’s t-test. It was demonstrated, that prolonged HFD induces IR and leads to changes in FA profile of adipocytes PL, TAG, CE and composition of FFA in rats from two age groups. The results we obtained shoved that the aging process affects the fatty acid composition of adipocytes. Particularly, there was a significant decrease in the amount of fatty acids in the fractions of phospholipids, triacylglycerols and cholesterol esters together with a decrease in the percentage of unsaturated fatty acids. It was also demonstrated, that HFD significantly alters the fatty acid composition of all investigated adipocytes lipid fractions of younger age group rats, while similar changes were much less manifested in older age group of animals. NSE administration had a positive effect on the normalization of the fatty acid composition of the studied lipid fractions of both age group rat adipocytes. This study demonstrated that prolonged HFD induces obesity, increases the risk of type 2 diabetes development and leads to changes in adipocytes FA profile in rats from two age groups. As far as NSE administration had a positive effect on normalization of FA composition of adipocytes, we can consider NSE as a prospective agent for the treatment of obesity-induced complications and correction of age-related dyslipidemia.

Comparative Assessment of Some Physicochemical Properties of Different Sesame Varieties and Oil Yield, Ethiopia

The proximate composition and physico chemical properties of released and improved Ethiopian sesame oil seed crops were evaluated. The results of statistical analyses showed significant variations in proximate composition values and physico chemical characteristics of sesame oil seed crops. The analysis of variance indicated that moisture content was ranged between 4.4% to 4.8%, total ash (4.70% to 8.72%), crude protein content (14.44% to 21.51%), crude fat /oil (44.40% to 50.84%) and carbohydrate was ranged between (16.23% to 29.46%). Maturity stage and storage conditions are the major factors for moisture contents. The lower moisture values indicated that there is low vulnerable for oil spoilage the so-called rancidity. Total ash values are the indication of inorganic elements that are present in food as minerals. From the ash values, comparatively Tate has a better mineral value as compared with others. Serkamo sesame variety has a better protein value while the minimum (14.44%) was recorded at Adi. This may due to the reason that protein values have direct correlation with agronomic practices. The oil contents of seed crops were significantly different; this may be due to genetic difference. The carbohydrate values have significant difference among varieties. These variations may be bringing form the concept that oil crops mostly have a better oil values, thus subtractions of carbohydrate from the proximate values have a significant effect on the carbohydrate’s values. On the other hand, the oil characterization of seed crops indicated that the range of saponification value was between (184.47 to 199.60 mgKOH/g), specific gravity (0.85 to 0.90), thousand seed weight (2.72 to 3.63 g), free fatty acid value (7.63 to 16.67%), ester value (151.32 to 182.90) and acid value (15.18 to 33.15 KOH/g). The physico chemical parameters of sesame oil seed crops were significantly different among varieties. This variation mainly exists due to genetic variabilities among the seed crops. From these ten different sesame varieties, Abasena with its lowest saponification value and high free fatty acid value indicated that the oil from this variety is regarded non-edible oil. Lower acid value indicated the oil stability against peroxidation. Abasena with its higher acid value indicated that the oil is not suitable for cooking as compared with the remain sesame varieties.

A Dinuclear Paddle-Wheel Cu(II) Complex [Cu2(L)4(H2O)2]·2H2O [HL=2-(Methoxycarbonyl)Benzoic Acid)]: Crystallographic, Magnetic, and Theoretical Analyses

A dinuclear paddle-wheel Cu(II) complex [Cu2(L)4(H2O)2]·2H2O (1) [HL=2-(methoxycarbonyl)benzoic acid)] is crystallized and characterized by spectral and magnetic analyses and single crystal X-ray crystallography. Single crystal XRD reveals that the complex crystallizes in the triclinic P-1 space group and has a square pyramidal environment around each copper(II) atom with a Cu ··· Cu intramolecular distance of 2.631 A. Noncovalent C-Hπp interactions generate a 1D chain, thus consolidating the crystal lattice. Such non-covalent interactions are verified theoretically by the Hirshfeld surface analysis, while a theoretical approach of molecular docking discloses the binding affinity of the complex with DNA which occurs interestingly in the major groove region through the free ester group present in the complex. Moreover, the temperature-variable magnetic data measured under an applied dc field of 0.1T in the temperature range 2-300 K show the presence of strong antiferromagnetic interactions between the two Cu(II) centres of the complex.

Determination of Saponification Value in Carnuba Wax by USP/NF Residual Titration Method <541>

Saponification value is defined as mg KOH needed to neutralize free acids and saponify esters in 1 g of the test substance. A search of the literature showed that the standard saponification methods of the U.S. Pharmacopeia, alcoholic potassium hydroxide were the only saponification reagent. The sample to investigate is saponified with an excess of ethanolic potassium hydroxide solution. After finished saponification the remaining excess of potassium hydroxide is determined by residual titration under Titrimetry , with aqueous volumetric hydrochloric acid. In this study, a test for saponification value has been successfully determined in carnuba wax. The average result has been found 90.9 mg KOH/g substance and, % RPD was 1.65%. This is in contradistinction to the U.S. Pharmacopeia/National Formulary (USP/ NF) Method.

A dinuclear paddle-wheel Cu(II) complex [Cu2(L)4(H2O)2]⋅2H2O (HL = 2-(methoxycarbonyl)benzoic acid): Crystallographic, magnetic, and theoretical analyses

A dinuclear paddle-wheel Cu(II) complex [Cu2(L)4(H2O)2]⋅2H2O (1) (HL = 2-(methoxycarbo­nyl)benzoic acid) is crystallized and characterized by spectral and magnetic analyses and single crystal X-ray crystallography. Single crystal XRD reveals that the complex crystallizes in the triclinic P–1 space group and has a square pyramidal environment around each copper(II) atom with a Cu⋯Cu intramolecular distance of 2.631 Å. Noncovalent C—H⋯π interactions generate a 1D chain, thus consolidating the crystal lattice. Such non-covalent interactions are verified theoretically by the Hirshfeld surface analysis, while a theoretical approach of molecular docking discloses the binding affinity of the complex with DNA which occurs interestingly in the major groove region through the free ester group present in the complex. Moreover, the temperature-variable magnetic data measured under an applied dc field of 0.1 T in the temperature range 2—300 K show the presence of strong antiferromagnetic interactions between the two Cu(II) centres of the complex.

Saponification of ethyl acetate in the presence of β-cyclodextrin

The saponification of ethyl acetate (EtAc) in the presence of β-cyclodextrin (β-CD) was measured by conductimetry at different temperatures within a batch reactor. A new mathematical model for obtaining reaction kinetics and concentration profiles from conductivity was derived. The observed rate constants (kobs) decrease with the increase in concentration of β-CD, at each temperature. This inhibitory effect is the result of the EtAc being complexed by β-CD, and the alkaline hydrolysis that occurred was due to the free ester in the solution, because the ester molecules included within the cyclodextrin cavity were unreactive. In the solution, the release of the guest is controlled by chemical equilibria. That is, the net concentrations of free ester decrease along with the increasing concentrations of cyclodextrin, which results in the deceleration of the reaction. From the kinetic data, the association equilibrium constant (K1:1) for the formation of the 1:1 inclusion complex was determined. K1:1 increased with an increase in temperature. The inclusive process was spontaneous and entropy-driven, an effect that results from the hydrophobic effect. The proposed saponification reaction mechanism and the dependence of the reaction rate on the temperature and concentration of cyclodextrin are consistent with the observed experimental results.

Variability of growth and oil characteristics of Jatropha curcas L. in North-east India

ABSTRACTSuccess of improvement of Jatropha curcas depends on wide germplasm from different agro-ecological regions showing specific and attractive traits. The present study aimed to compare characteristics of 28 jatropha accessions in the light of enhancing the viability of the oil-based biodiesel chain. The tested jatropha accessions showed a wide range of responses. The plant morphology (height, branching and leaves) also indicated some vigorous genotypes. The growth was accompanied by a wide range of leaf gas exchange (CO2 and moist) that gave water use efficiency values ranging between 0.5 and 8.5. The morphological and physiological differences had no significant influence on seed weight (67–76 g/100 seeds). Oil yield with a mean value of 27.93% can be considered a medium yield for jatropha; only few accessions had oil over 30%. However, differences were well evident in free fatty acid (1.4–28.7%), phorbol ester (PE, 1.1–4.3 mg/g oil), tocopherol (73.7–907.8 ng/mg oil) and unsaturated fatty acid (78.8–90.8%) contents. The present data support studies to correlate genetic, morphological, physiological and biochemical traits in each genotype considered for future selection of ideotypes with low undesirable free fatty acid contents, and potential valorisation of secondary oil products (PEs, tocopherols) to enhance the economic viability and sustainability of the jatropha oil-based biodiesel chain.

Bile lipids in rats under chronic social stress

Our experiments studied changes in lipid compound of bile of non-purebred male rats under the condition of social stress while the preparation “Korvitin” was used against the stress. Using the method of thin-layer chromatography, we determined the concentrations of phospholipids, cholesterol and its esters, free fatty acids and triglycerides in the animals’ bile, which was obtained through vivesection a day and a month after the rats were first subjected to chronic social stress (model of social defeat), and also in the bile of the animals which were treated intragastrically with “Korvitin” against the stress (1 mg/kg, 7 days). In the bile of the male rats which experienced chronic social stress the concentration of free cholesterol decreased and the content of its esters increased both immediately after the initiation of stress and after a month of exposure to stress. The concentration of free fatty acids in the bile decreased after modeling chronic social stress, but increased in liver secretion, taken a month after the animals first experienced stress. In the bile of male rats immediately after the procedure of exposing the animals to stress, the content of phospholipids decreased. Using “Korvitin” during the modeling of social stress caused decrease in the content of phospholipids in the rats’ bile and caused significant increase in the concentration of free fatty acids, triglycerides and cholesterol esters in the liver secretion. The study found significant changes in the concentration of lipids in the bile and in their distribution in the organism of male rats under the conditions of experimentally induced chronic stress. The effect of stress on the bile of rats requires further study for determining its pathogenic role.

‘Fortified’ wines volatile composition: Effect of different postharvest dehydration conditions of wine grapes cv. Malvasia moscata (Vitis vinifera L.)

The impact of postharvest dehydration on the volatile composition of Malvasia moscata grapes and fortified wines produced from them was assessed. The ripeness effect of fresh grapes on volatile compounds of dehydrated grapes was evaluated for the first time in this study. Fresh grape berries were densimetrically sorted, and more represented density classes were selected. Dehydration of riper berries (20.5 °Brix) led to volatile profiles richer in terpenes, particularly linalool and geraniol. The effect of dehydration rate on the volatile composition of dehydrated grapes and fortified wines was also evaluated. Fast dehydration grapes were richer in total free terpenes, and the resulting wines contained greater amounts of volatile compounds. The predominant compounds were free esters, but linalool, rose oxide, citronellol and geraniol can also contribute to wine aroma, particularly for fast dehydration. β-Damascenone can be an active odorant, although its contribution was greater in wines made from slow dehydrated grapes.

Influence of vacuum on kinetic of low quality rapeseed oil amidation by aminoethylethanolamine

The process of direct amidation of low­grade canola oil with high free fatty acids content has been researched. Influence of different technological parameters on consumption of reagents and accumulation of reaction products have been established for the temperature of reaction 160 °С. Concentrations of esters, free fatty acids, alkylimidazolines and amine components have been determined during the reaction time. Application of vacuum during the amidation process has great influence on free fatty acids consumption as well as on alkylimidazoline formation. Effective rate constants have been calculated for reactions of conversion of free fatty acids and esters into amides with and without vacuum. It has been determined that effective rate constant of free fatty acids consumption under atmospheric pressure is three times lower than under vacuum 40–60 mm. Hg. as well as those for esters. Along with an increase in free fatty acids consumption, the speed of alkylimidazolines formation rapidly increases with vacuum applying. Such effect is explained by shifting of equilibrium in reactions of free fatty acids consumption and alkylimidazoline formation by removing of reaction water by vacuum. Formation of amides of fatty acids and alkylimidazolines confirmed by IR­spectroscopy.

Isolasi Bakteri Penghasil Lipase dengan Kemampuan Esterase untuk Produksi Metil Ester

Lipase (triasilglieserol hidrolase, EC 3.1.1.3) is an enzyme that can hydrolyze mono-and di and tri acylglycerols (TAG) into free fatty acids, glycerol. Lipase has esterase activity that can form between free fatty acid esters with alcohols. Microorganisms that produced lipase spread from molds, yeasts, and bacteria. Four isolates of bacterial lipolytic ( SG_T , SG_Z , DS_T , and DS_Z ) that has the ability esterase for fatty acids from olive oil and methanol have been isolated from typical Indonesian food containing high oil (fried cassava , dodol salak). Media isolation which used are tributyrin agar –tributyrin and tributyrin - olive oil. Fried cassava isolates have a tendency to live in an acidic pH environment , while isolates dodol salak (fruit snake) has a tendency to live at alkaline pH . All isolates showed that the optimum production of lipase (from 0.45 to 0.73 U m ) was achieved in the range of 32 -hour incubation time (room temperature ) . Fried cassava isolates showed the highest esterase activity, which produce the largest methyl ester is 15.303%. This isolates is a potential lipolytic bacterial as a lipase producer for production of fatty acid methyl ester ( FAME ) / enzymatic biodiesel

Effect of solvent on the extraction of microalgae lipid for biodiesel production

The effect of solvent on the microalgae lipid extraction was studied. The efficiency of lipid extraction from microalgae was found to differ according to the solvent used. The existence of formic acid contributed to the extraction of lipid to a great extent. With 8 mg/L formic acid existing in the system, the lipid yield and free fatty methyl ester(FAME) yield increased from 39% to 42% and from 81% to 90% respectively compared to the control. The highest lipid yield of 42% was achieved from Chlorella protothecoidesis with an FAME yield of 89% when a mixed solvent of 14 mL/g dichloromethane, 2 mL/g methanol and 4 mL/g formic acid was used.