The behavior of distilled monoglycerides in the presence of water

Summary When concentrated monoglycerides (such as distilled products) are heated to about their melting point with water, a gel is formed. The exact temperature of gelation is dependent upon molecular weight of the fatty acid (monolaurin does not gel, but monopalmitin does) and upon the the purity of the monoglyceride. Additives can prevent gelation, with triglycerides (15% to 20% required) about twice as effective as diglycerides (30% to 40% required). Highly hydrophilic co-emulsifiers prevent gelation, resulting in one of three types of emulsions, at least two of which are thixotropic. Water is partially soluble in monoglycerides and in monoglyceride containing blends. By this technique many water-soluble materials can be incorporated into an oil solution. Communication No. 240 from the laboratories of Distillation Products Industries.     

Squirting and refilling: Dynamics ofp-benzoquinone production in defensive glands ofDiploptera punctata

Diploptera punctata, a Pacific islands cockroach, discharges a fine aerosol ofp-benzoquinones from a pair of tracheal glands in response to disturbance or CO₂ anesthesia. In addition, the glands and their contents are shed at each molt. We measured the amount ofp-benzoquinones discharged in response to pinching and anesthesia and the filling of glands after discharge and molting. Roaches discharge highly variable amounts of quinones but appear to retain approximately 11% of their lifetime total benzoquinone content after repeated discharges. Roaches rapidly fill their glands after molting (18g quinone/day) but after discharging appear to refill at a much slower rate or not at all. This lack of refilling could result from an inability to produce quinones after a finite time period or in excess of a fixed quantity. The delayed accumulation ofp-benzoquinone with respect to the alkylated derivatives in newly molted adults suggests competition for aromatic amino acids between cuticular and defensive quinone synthesis.Paper 92 in the series Defense Mechanisms of Arthopods. Paper 91 is T. Eisner, M. Eisner, T. Jaouni, and H.M. Fales. 1990.p-Methoxyphenol: Chemical basis of stench of a female butterfly.Naturwissenschaften 77:33.     

Physiological activity of water beetle defensive agents. I. Toxicity and anesthetic activity of steroids and norsesquiterpenes administered in solution to the minnowPimephales promelas Raf.

By means of a bioassay employing the minnowPimephales promelas, the anesthetic activities and toxicities of various defensive steroids and norsesquiterpenes produced by the Dytiscidae and Gyrinidae were compared with those of a wide selection of steroid standards. The most widely occurring major components of dytiscid secretions, 4-pregnen-3-ones and related derivatives, were among those compounds most active in minnow bioassays. The norsesquiterpenes gyrinidal and gyrinidione were among the most toxic compounds tested but they possessed little anesthetic action. The anesthetic activity of gyrinidone was comparable to that of testosterone. Steroid activity in the minnow bioassay was highly related to the degree of oxygenation; steroids oxygenated only at the termini of the molecule were most active. Less or additional oxygenation resulted in a loss of activity. When steroids were rapidly administered to minnows the activities of many of them were similar, suggesting they share a common mode of action.     

The estimation of lactic acid in lactylated monoglycerides and shortenings containing lactylated monoglycerides

A titrimetric method has been presented for the determination of lactic acid in lactylated monoglycerides and shortenings containing these products, when the only water soluble acid present is lactic acid. Analyses by this method: of knowns, samples from a material balance test, and commercial products, indicate that it is applicable to these types of product. Comparison of analyses of the material balance samples and commercial products by the titrimetric method and the colorimetric p-phenylphenol method indicated that the latter gave lower and more variable results.     

Physiological activity of water beetle defensive agents. II. Absorption of selected anesthetic steroids and norsesquiterpenes across gill membranes of the minnowPimephales promelas Raf.

The uptake of selected steroids and norsesquiterpenes by live minnows,Pimephales promelas, was studied when the compounds were administered externally in aqueous solution. The gills of minnows absorbed 80% of the steroid removed from solution. Steroid absorption across minnow gills is apparently a nonmediated process as rate saturation could not be demonstrated. Initial absorption rates of test compounds were inversely correlated with (1) the degree of oxygenation, (2) water solubility, and (3) polarity on silica gel thin-layer chromatography. These findings support the Stein model of non-mediated transport. The majority of compounds anesthetic and toxic to minnows exerted their effects at a similar internal concentration. Anesthesia occurred at ca. 10^–6–10^–5 M and death at 10^–4–10^–3 M. Since various agents causing membrane stabilization and lysis in in vitro systems act in an identical concentration range, it is proposed that the defensive steroids and norsesquiterpenes of water beetles act via membrane stabilization and lysis.     

The preparation and purification of monoglycerides

Mono- and diglycerides were produced by reacting the following oils with glycerol: coconut, peanut, sesame, linseed, and sardine. It was shown that the yield of monoglyceride was not dependent upon the fatty acid composition of the oil but on the solubility of glycerol in oil, which is dependent in part on the temperature. An excess of glycerol above that which is soluble does not change the composition of the reaction product. At 180°C, no more than 45% monoglycerides can be formed by glycerolysis. Presented at the 51st annual spring meeting, Dallas, Texas, April 4–6, 1960.     

The determination of monoglycerides and glycerin in mixtures

A new method of analyzing mixtures containing monoglyceride and glycerin is presented. It is based upon oxidation of the sample with periodic acid. The new method is more rapid than the older methods because it is not necessary to separate the two layers when the glycerin is extracted from the solution of the sample. Precision of the titrations is improved because in the older methods the sample titration must equal at least 80% of the blank titration, but in the new method the sample titration can be very small and a correspondingly greater difference represents the monoglyceride or glycerin in the sample.     

Enzymatic preparation of monoglycerides in microemulsion

Monoglycerides have been obtained in 80% yield by enzyme catalyzed hydrolysis of the corresponding triglyceride. The reaction was carried out in an oil-rich microemulsion (L 2 phase) formulated without cosurfactant. Best results were obtained with the anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT), isooctane as hydrocarbon component and a molar ratio of aqueous buffer of pH 7 to surfactant of 12. The enzyme used was a 1,3-specific lipase which leaves the 2- position intact. However, the 2-monoglyceride formed slowly undergoes acyl migration to 1-monoglyceride which subsequently is hydrolyzed to glycerol and fatty acid. Optimal reaction time at 35 C reaction temperature was found to be three hr.     

Determination of monoglycerides in crude oils and fats

The periodate oxidation method was adapted for the determination of small amounts of monolycerides present in natural oils and fats. The modification consisted in enriching the monoglycerides by extraction with 90% acetic acid saturated with boric acid in order to eliminate interfering substances prior to the reaction with periodate. A multifold concentration of monoglycerides originally present was achieved. This reduced the error of the standard periodate method to a minimum. Crude oils, such as soybean, rice bran, coconut, and palm, analyzed by the modified method showed monoglyceride contents considerably lower than those obtained by direct reaction of periodate with these oils.     

Increasing the stability of vegetable oil solutions with the aid of monoglycerides and a cosurfactant

The conditions for an enhanced mutual miscibility of water and Canola oil, with the aid of one or two surface active components, were investigated at 25 C. First, the ability of short chain alcohols to increase the mutual solubility was charted. Such systems frequently are denoted detergentless microemulsions. Second, normal microemulsion systems were formed by using surface active monoglycerides of foodstuff grade. Third, the synergism was monitored when both the surfactant and the cosurfactant (the alcohols) were mixed either with water or oil. Finally, the combined effect was determined when all four components were mixed together into a microemulsion system. It is shown that the extension of the ternary solution phase is dependent primarily on the surfactant used. Some improvement of the mutual solubility of water and oil, however, also was produced by the alcohols. The solubilization capacity of water in the quaternary systems is easily understood when the solution phase is compared with the microemulsion phases of the ternary systems included. Although no dramatic composition dependency was found, an enhanced solubility of water was observed for the oil rich microemulsions of roughly equal weight fractions of the surfactant components. Presented in part at the 8th Scandinavian Symposium on Surface Chemistry, Lund, Sweden, 1984.     

Glycerolysis of marine oils and the preparation of acetylated monoglycerides

Conclusions The glycerolysis reaction was applied to menhaden, tuna, herring, sardine, and salmon-egg oils. Optimum reaction time for the preparation of α-monoglycerides was found to vary, reproducibly, from 45 to 60 min., depending on the particular kind of marine oil employed. The method was suitable for the preparation of kilogram quantities. A laboratory method for the prepagation of kilogram quantities of highly pure acetylated α-mono-glycerides was developed. Both the glycerolysis mixtures from marine oils and their acetylated products were light in color and substantially free of odor. Thin-layer silicic acid chromatography, as described here, was found suitable for the analysis of acetoglycerides from marine oils. The work indicated that the method may have wide use for the separation and identification of other lipid classes as well. This is Contribution No. 497 from the technological laboratories of the Bureau of Commercial Fisheries, Fish and Wildlife Service, U. S. Department of the Interior. This is a laboratory of the Division of Industrial Research and Services, Bureau of Commercial Fisheries, U. S. Fish and Wildlife Service, Department of the Interior.     

合成系列高纯度单脂肪酸甘油酯

用丙酮保护的一锅合成法,即通过甘油与丙酮反应制得异亚丙基甘油,在对甲苯磺酸催化作用下与脂肪酸反应制备了单月桂酸甘油酯、单肉豆蔻酸甘油酯、单棕榈酸甘油酯、单硬脂酸甘油酯、单山嵛酸甘油酯5种单脂肪酸甘油酯。制备的系列单脂肪酸甘油酯的质量分数均大于90%,收率都高于75%。并根据熔点测定和红外图谱分析结果,确定了产物结构。实验发现系列单甘酯合成中脂肪酸碳数与反应难易间的规律为:脂肪酸碳数越多,反应越难于进行,单甘酯的质量分数和收率也越低,这一规律与热力学计算所得规律一致。     

Enzymatic synthesis of monoglycerides in a membrane bioreactor with an in-line adsorption column

The chemical synthesis of monoglycerides requires high temperatures, which may lead to the polymerization of unsaturated fatty acids. The enzymatic synthesis of these esters is performed at moderate temperatures and, hence, polymerization is avoided. However, enzymatic processes often end up with a mixture of the product, by-product, substrate and enzyme. An alternative process is an immobilized enzyme membrane reactor equipped with an inline adsorption column to adsorb the monoglycerides, preferentially onto the adsorbate. A silica 60 column has shown preferential adsorption of monocaprinate. The adsorption of a mixture of decanoic acid, mono- and diglycerides is based on two different mechanisms. The decanoic acid will interact with hydroxyl groups at the silica gel surface, which results in a noncompetitive decanoic acid adsorption onto 25% of the silica gel surface. On the remaining part of the silica gel surface, mono- and diglycerides adsorb competitively. When a mild eluant is used, such as 5% ethanol in hexane, only the competitively adsorbed molecules are desorbed. This results in a purification factor of approximately 90% after desorption. The column can be desorbed off-line in a continuous membrane/repeated batch column process. This results in an estimated production of monoglycerides of 60 mol (15 kg) of monoester per gram enzyme.     

Sequestration and metabolism of protoxic pyrrolizidine alkaloids by larvae of the leaf beetle Platyphora boucardi and their transfer via pupae into defensive secretions of adults

Several neotropical leaf-beetles of the genus Platyphora ingest and specifically metabolize plant acquired pyrrolizidine alkaloids (PAs) of the lycopsamine type (e.g., rinderine or intermedine) and enrich the processed alkaloids in their exocrine defensive secretions. In contrast to the related palaearctic leaf beetles of the genus Oreina, which absorb and store only the non-toxic alkaloid N-oxides, Platyphora sequesters PAs exclusively as protoxic tertiary amines. In this study, the ability of P. boucardi larvae to accumulate PAs was investigated. Tracer studies with [¹⁴C]rinderine and its N-oxide revealed that P. boucardi larvae, like adult beetles, utilize the two alkaloidal forms with the same efficiency, but accumulate the alkaloid as a tertiary amine exclusively. Ingested rinderine is rapidly epimerized to intermedine, which is localized in the hemolymph and all other tissues; it is also detected on the larval surface. Like adults, larvae are able to synthesize their own alkaloid esters (beetle PAs) from orally administered [¹⁴C]retronecine and endogenous aliphatic 2-hydroxy acids. These retronecine esters show the same tissue distribution as intermedine. A long-term feeding experiment lasting for almost four months revealed that retronecine esters synthesized from [¹⁴C]retronecine in the larvae are transferred from larvae via pupae into the exocrine glands of adult beetles. Pupae contain ca. 45% of the labeled retronecine originally ingested, metabolized, and stored by larvae; ca. 12% of larval radioactivity could be recovered from the defensive secretions of adults sampled successively over two and a half months. Almost all of this radioactivity is found in the insect-made retronecine esters that are highly enriched in the defensive secretions, i.e., more than 200-fold higher concentration compared to pupae.     

The Shared Proteome of the Apomictic Fern Dryopteris affinis ssp. affinis and Its Sexual Relative Dryopteris oreades

Ferns are a diverse evolutionary lineage, sister to the seed plants, which is of great ecological importance and has a high biotechnological potential. Fern gametophytes represent one of the simplest autotrophic, multicellular plant forms and show several experimental advantages, including a simple and space-efficient in vitro culture system. However, the molecular basis of fern growth and development has hardly been studied. Here, we report on a proteomic study that identified 417 proteins shared by gametophytes of the apogamous fern Dryopteris affinis ssp. affinis and its sexual relative Dryopteris oreades. Most proteins are predicted to localize to the cytoplasm, the chloroplast, or the nucleus, and are linked to enzymatic, binding, and structural activities. A subset of 145 proteins are involved in growth, reproduction, phytohormone signaling and biosynthesis, and gene expression, including homologs of SHEPHERD (SHD), HEAT SHOCK PROTEIN 90-5 (CR88), TRP4, BOBBER 1 (BOB1), FLAVONE 3’-O-METHYLTRANSFERASE 1 (OMT1), ZEAXANTHIN EPOXIDASE (ABA1), GLUTAMATE DESCARBOXYLASE 1 (GAD), and dsRNA-BINDING DOMAIN-LIKE SUPERFAMILY PROTEIN (HLY1). Nearly 25% of the annotated proteins are associated with responses to biotic and abiotic stimuli. As for biotic stress, the proteins PROTEIN SGT1 HOMOLOG B (SGT1B), SUPPRESSOR OF SA INSENSITIVE2 (SSI2), PHOSPHOLIPASE D ALPHA 1 (PLDALPHA1), SERINE/THREONINE-PROTEIN KINASE SRK2E (OST1), ACYL CARRIER PROTEIN 4 (ACP4), and NONHOST RESISTANCE TO P. S. PHASEOLICOLA1 (GLPK) are worth mentioning. Regarding abiotic stimuli, we found proteins associated with oxidative stress: SUPEROXIDE DISMUTASE[CU-ZN] 1 (CSD1), and GLUTATHIONE S-TRANSFERASE U19 (GSTU19), light intensity SERINE HYDROXYMETHYLTRANSFERASE 1 (SHM1) and UBIQUITIN-CONJUGATING ENZYME E2 35 (UBC35), salt and heavy metal stress included MITOCHONDRIAL PHOSPHATE CARRIER PROTEIN 3 (PHT3;1), as well as drought and thermotolerance: LEA7, DEAD-BOX ATP-DEPENDENT RNA HELICASE 38 (LOS4), and abundant heat-shock proteins and other chaperones. In addition, we identified interactomes using the STRING platform, revealing protein–protein associations obtained from co-expression, co-occurrence, text mining, homology, databases, and experimental datasets. By focusing on ferns, this proteomic study increases our knowledge on plant development and evolution, and may inspire future applications in crop species.     

Kinetics of acyl migration in monoglycerides and dependence on acyl chainlength

The chemical rearrangement reaction of β- into α-monoglycerides is described. Four monoglycerides with different fatty acid chainlength have been investigated, and the equilibrium constant and the reaction velocity constants characterizing the reaction of the chemical rearrangement were estimated with a mathematical model. A 1∶6.5 mixture of α/β-monoglycerides appeared to rearrage to a mixture of 1∶1 α/β-monoglycerides within 24 h. Furthermore, the reaction velocity of the rearrangement reaction of β- to α-monoglycerides depended on the fatty acyl chainlength in the monoglyceride.     

Further improvements in the yield of monoglycerides during enzymatic glycerolysis of fats and oils

Three approaches were used in an effort to increase the yield of monoglycerides (MG) during the lipase catalyzed reaction of glycerol with triglyceride fats and oils: i) various commercially available lipases were screened for ability to catalyze MG synthesis; ii) mixtures of lipases were compared with single lipases; and iii) two-step temperature programming was applied during the reaction. Of these, temperature programming was found to be the most effective. With an initial temperature of 42°C for 8–16 hr followed by incubation at 5°C for up to 4 days, a yield of approximately 90 wt% MG was obtained from beef tallow, palm oil and palm stearin. When the second incubation temperature was greater than 5°C, the yield of MG was progressively lower with increasing temperature. In the case of screening of newly available commercial lipase preparations, lipases fromPseudomonas sp. were found to be most effective, giving a yield of approximately 70 wt% MG at 42°C from tallow. Lipases fromGeotrichum candidum, Penicillium camembertii (lipase G) andCandida rugosa were inactive. A mixture of lipases fromPenicillium camembertii andHumicola lanuginosa was found to be more effective than either enzyme alone, giving a yield of approximately 70 wt% MG using beef tallow or palm oil. A mixture ofPenicillium camembertii lipase with eitherPseudomonas fluorescens lipase orMucor miehei lipase was not more effective thanPseudomonas fluorescens orMucor miehei lipase alone.     

Lipase G-Catalyzed synthesis of monoglycerides in organic solvent and analysis by HPLC

Monoglycerides were synthesized with Lipase G fromPenicillium sp. as biocatalyst. This enzyme successfully catalyzed the esterification of glycerol with oleic acid (18:1 n-9) or eicosapentaenoic acid, EPA (20:5 n-3) in hexane. Esterification at 40°C for 24 hr resulted in 86.3 mol% and 64.3 mol% incorporation of 18:1 n-9 and 20:5 n-3, respectively. Lipase GC fromGeotrichum candidum was not effective in esterifying the fatty acids under the present experimental conditions. Lipase G was able to incorporate 98.5 mol% and 98.1 mol% of 18:1 n-9 onto glycerol in 24 hr or less at 25°C and 37°C, respectively, in the absence of molecular sieve 4A. The product formed was analyzed by high performance liquid chromatography (HPLC) with a combined evaporative light scattering mass detector (ELSD) and ultraviolet detection at 206 nm. The result of this study demonstrates that Lipase G is capable of incorporating long-chain fatty acids of potential health benefit onto glycerol.     

Appraisal of methods of total monoester estimation in commercial monoglycerides

Analytical techniques of estimating total monoglycerides in industrial products and difficulties encountered in their estimation are critically discussed. A modification is suggested of a recently published procedure which combines the “Partition method” with the methods of Martin and of Brokawet al. A tentative method of determining total monoglycerides based on simultaneous isomerization and periodate oxidation is described. *** DIRECT SUPPORT *** A03O2182 00005     

Solubility of monoglycerides in oil and its relation to the production of global edible spread

Summary Solubility data have been presented for monostearin, monopalmitin, and monoglycerides of triple-pressed stearic acid and hydrogenated lard in cotton-seed oil. Monoglyceride precipitated from solution by quick chilling became less soluble after tempering 18 hrs. at 45°C. Decreased solubility was related to increased crystallinity as determined by X-ray diffraction. Solubility data thus confirmed conclusions previously reported that tempering operates to improve global spread primarily through recrystallization which is now shown to involve converting precipitates of low degree of molecular order into more perfect crystals. Presented at the fall meeting of the American Oil Chemists’' Society, Minneapolis, Minn., Oct. 11–13, 1954.