Positional distribution of Δ5-acids in triacylglycerols from conifer seeds as determined by partial chemical cleavage

The positional distribution of various Δ5-acids in the seed triacylglycerols from several conifer species has been established after partial chemical degradation with Grignard reagent. The species studied were representative of four conifer families and were specially selected for their particularly high Δ5-acid contents. These species were Taxus baccata (Taxaceae; 5,9-18:2 acid, 11.9%), Larix decidua (Pinaceae; 5,9,12-18:3 acid, 28.5%), Sciadopytis verticillata (Taxodiaceae; 5,11,14-20:3 acid, 16.7%), and Juniperus communis (Cupressaceae; 5,11,14,17-20:4 acid, 19.8%). Calculations from the fatty acid compositions of triacylglycerols and of the mixture of 1,2- and 2,3-diacylglycerols generated by the Grignard reagent indicated that, for the four species, there was a considerable enrichment of Δ5-acids (generally more than ten times) in the 1,3-positions as compared to the 2-position, where Δ5-acids represented always less than 2% of total fatty acids esterified to triacylglycerols. This distribution was practically independent from the species (four families studied), the chainlength (18 or 20 carbon atoms), and the number of ethylenic bonds (two to four) in the Δ5-acids. Similar distributions were established for triacylglycerols from the seeds of three pine species that are available on a ton-scale: Pinus pinea, P. koraiensis, and P. pinaster. These observations confirm and extend previous studies conducted with other conifer species by similar techniques or by ¹³C-nuclear magnetic resonance spectroscopy. Consequently, the almost exclusive location of Δ5-acids in the external positions of triacylglycerols is now well established and appears to be a general feature of conifer seed oils.     

Structure−property relationships of halogen‐free flame‐retarded poly(butylene terephthalate) and glass fiber reinforced PBT

Flame retardancy for thermoplastics is a challenging task where chemists and engineers work together to find solutions to improve the burning behavior without strongly influencing other key properties of the material. In this work, the halogen‐free additives aluminum diethylphosphinate (AlPi‐Et) and a mixture of aluminum phosphinate (AlPi) and resorcinol‐bis(di‐2,6‐xylyl phosphate) (AlPi‐H + RXP) are employed in neat and reinforced poly(butylene terephthalate) (PBT), and the morphology, mechanical performance, rheological behavior, and flammability of these materials are compared. Both additives show submicron dimensions but differ in terms of particle and agglomerate sizes und shapes. The overall mechanical performance of the PBT flame‐retarded with AlPi‐Et is lower than that with AlPi‐H‐RXP, due to the presence of larger agglomerates. Moreover, the flow behavior of the AlPi‐Et/PBT materials is dramatically changed as the larger rod‐like primary particles build a percolation threshold. In terms of flammability, both additives perform similar in the UL 94 test and under forced‐flaming combustion. Nevertheless, AlPi‐Et performs better than AlPi‐H + RXP in the LOI test. The concentration required to achieve acceptable flame retardancy ranges above 15 wt %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

FA composition and regiospecific analysis of Acer saccharum (sugar maple tree) and Acer saccharinum (silver maple tree) seed oils

GC analysis was performed to determine regiospecific distribution and FA composition in seed oils of the Aceraceae species, Acer saccharum and A. saccharinum. The oil content in the seeds was low at 5.0% in A. saccharum and 5.8% in A. saccharinum, and the main FA were linoleic (30.8 and 29.4%), oleic (21.3 and 27.6%), palmitic (10.1 and 10.5%), and cis-vaccenic (9.4 and 7.9%) acids, respectively. In addition, both oils contained long-chain monoenes of the n−9 and n−7 groups, including 11-eicosenoic, 13-docosenoic, 15-tetracosenoic, 13-eicosenoic, and 15-docosenoic acids, whereas γ-linolenic acid accounted for 0.8% of total FA in A. saccharum, and 0.5% in A. saccharinum. Regiospecific analysis, performed using the methodology of dibutyroyl derivatives of MAG, indicated that linoleic, oleic, and linolenic acids were mainly esterified at the internal position of TAG in both seed oils, whereas long-chain monoenes of the n−7 group were almost exclusively esterified on the external positions.     

Abietoid seed fatty acid composition—A review of the genera Abies, Cedrus, Hesperopeuce, Keteleeria, Pseudolarix, and Tsuga and preliminary inferences on the taxonomy of Pinaceae

The seed fatty acid (FA) compositions of Abietoids (Abies, Cedrus, Hesperopeuce, Keteleeria, Pseudolarix, and Tsuga) are reviewed in the present study in conclusion to our survey of Pinaceae seed FA compositions. Many unpublished data are given. Abietoids and Pinoids (Pinus, Larix, Ficea, and Pseudotsuga)—constituting the family Pinaceae—are united by the presence of several Δ5-olefinic acids, taxoleic (5,9–18∶2), pinolenic (5,9,12–18∶3) coniferonic (5,9,12,15–18∶4), keteleeronic (5,11–20∶2), and sciadonic (5,11,14–20∶3) acids, and of 14-methyl hexadecanoic (anteiso-17∶0) acid. These acids seldom occur in angiosperm seeds. The proportions of individual Δ5-olefinic acids, however, differ between Pinoids and Abietoids. In the first group, pinolenic acid is much greater than taxoleic acid, whereas in the second group, pinolenic acid is greater than or equal to taxoleic acid. Moreover, taxoleic acid in Abietoids is much greater than taxoleic acid in Pinoids, an apparent limit between the two subfamilies being about 4.5% of that acid relative to total FA. Tsuga spp. appear to be a major exception, as their seed FA compositions are much like those of species from the Pinoid group. In this respect, Hesperopeuce mertensiana, also known as Tsuga mertensiana, has little in common with Abietoids and fits the general FA pattern of Pinoids well. Tsuga spp. and H. mertensiana, from their seed FA compositions, should perhaps be separated from the Abietoid group and their taxonomic position revised. It is suggested that a “Tsugoid” subfamily be created, with seed FA in compliance with the Pinoid pattern and other botanical and immunological criteria of the Abietoid type. All Pinaceae genera, with the exception of Pinus, are quite homogeneous when considering their overall seed FA compositions, including Δ5-olefinic acids. In all cases but one (Pinus), variations from one species to another inside a given genus are of small amplitude. Pinus spp., on the other hand, have highly variable levels of Δ5-olefinic acids in their FA compositions, particularly when sections (e.g., Cembroides vs. Pinus sections) or subsections (e.g., Flexiles and Cembrae subsections from the section Strobus) are compared, although they show qualitatively the same FA patterns characteristic of Pinoids. Multicomponent analysis of Abietoid seed FA allowed grouping of individual species into genera that coincide with the same genera otherwise characterized by more classical botanical criteria. Our studies exemplify how seed FA compositions, particularly owing to the presence of Δ5-olefinic acids, may be useful in sustaining and adding some precision to existing taxonomy of the major family of gymnosperms, Pinaceae.     

Regiospecific analysis of conifer seed triacylglycerols by gas-liquid chromatography with particular emphasis on Δ5-olefinic acids

Dibutyroyl derivatives of monoacylglycerols (DBMAG) from conifer seed oil triacylglycerols (TAG) were prepared by partial deacylation of TAG with ethylmagnesium bromide followed by diesterification with n-butyryl chloride. The resulting mixtures were analyzed by gas-liquid chromatography (GCL) with 65% phenylmethyl silicon open tubular fused-silica capillary column operated under optimal conditions and separated according to both their fatty acid structures and their regiospecific distribution. Seed oils of 18 species from 5 conifer families (Pinaceae, Taxaceae, Cupressaceae, Cephalotaxaceae, and Podocarpaceae) were analyzed. The chromatograms showed a satisfactory resolution of DBMAG containing palmitic (16∶0) stearic (18∶0), taxoleic (cis-5, cis-9 18∶2), oleic (cis-9 18∶1), cis-vaccenic (cis-11 18∶1), pinolenic (cis-5, cis-9, cis-12 18∶3), linoleic (cis-9, cis-12 18∶2), α-linolenic (cis-9 cis-12, cis-15 18∶3), and an almost baseline resolution of DBMAG containing gondoic (cis-11 20∶1), cis-5, cis-11 20∶2, sciadonic (cis-5, cis-11, cis-14 20∶3), dihomolinoleic (cis-11 cis-14 20∶2), juniperonic (cis-5, cis-11, cis-14, cis-17 20∶4), and dihomo-α-linolenic (cis-11, cis-14, cis-17 20∶3) acids. We have observed that results for Pinus pinaster and P. koraiensis seed oils obtained with this new simple method compared favorably with literature data established with other usual regiospecific analytical techniques. Δ5-Olefinic acids are esterified mainly at the external positions of the glycerol backbone in all cases, in agreement with data obtained by other methodologies allowing validation of the GLC regiospecific method. To date, 45 gymnosperm species (mostly Coniferophytes) from 21 genera belonging to 9 families have been analyzed, all of them showing a definite enrichment of Δ5-olefinic acids in the external positions of TAG. These fatty acids (FA), with one exception only, represent between-2 and 8% of FA esterified to the internal positions. For some species, i.e., P. koraiensis and P. pinaster, this asymmetrical distribution was established by at least three analytical procedures and confirmed by stereospecific analysis of their seed TAG.     

ATMOSPHERIC FREEZE-DRYING PART 1 : DESIGN,EXPERIMENTAL INVESTIGATION AND ENERGY-SAVING ADVANTAGES

This paper describes the experimental study of a new process for freeze-drying based on a fluidized bed of dry adsorbent working at atmospheric pressure. Process feasibility has been demonstrated. The kinetics of dehydration have been established systematically for thin-sliced potatoes. A comparison has been carried out with vacuum freeze-drying. Processing time is longer than under vacuum freeze-drying, but energy savings of 35% can be expected from a continuous duty facility.     

Arachidonic, eicosapentaenoic, and biosynthetically related fatty acids in the seed lipids from a primitive gymnosperm, Agathis robusta

The fatty acid composition of the seeds from Agathis robusta, an Australian gymnosperm (Araucariaceae), was determined by a combination of chromatographic and spectrometric techniques. These enabled the identification of small amounts of arachidonic (5,8,11,14–20∶4) and eicosapentaenoic (5,8,11,14,17–20∶5) acid for the first time in the seed oil of a higher plant. They were apparently derived from γ-linolenic (6,9,12–18∶3) and stearidonic (6,9,12,15–18∶4) acids, which were also present, via chain elongation and desaturation, together with other expected biosynthetic intermediates [bis-homo-γ-linolenic (8,11,14–20∶3) and bishomo-stearidonic (8,11,14,17–20∶4) acids]. Also present were a number of C₂₀ fatty acids, known to occur in most gymnosperm families, i.e., 5,11–20∶2, 11,14–20∶2 (bishomo-linoleic), 5,11,14–20∶3 (sciadonic), 11,14,17–20∶3 (bishomo-α-linolenic), and 5,11,14,17–20∶4 (juniperonic) acids. In contrast to most other gymnosperm seed lipids analyzed so far, A. robusta seed lipids did not contain C₁₈ Δ5-desaturated acids [i.e., 5,9–18∶2 (taxoleic), 5,9,12–18∶3 (pinolenic), or 5,9,12,15–18∶4 (coniferonic)]. These structures support the simultaneous existence of Δ6- and Δ5-desaturase activities in A. robusta seeds. The Δ6-ethylenic bond is apparently introduced into C₁₈ polyunsaturated acids, whereas the Δ5-ethylenic bond is introduced into C₂₀ polyunsaturated acids. A general metabolic pathway for the biosynthesis of unsaturated fatty acids in gymnosperm seeds is proposed. When compared to Bryophytes, Pteridophytes (known to contain arachidonic and eicosapentaenoic acids), and species from other gymnosperm families (without such acids), A. robusta appears as an “intermediate,” with the C₁₈ Δ6-desaturase/C₁₈→C₂₀ elongase/C₂₀ Δ5-desaturase system in common with the former subphyla, and the unsaturated C₁₈→C₂₀ elongase/C₂₀ Δ5-desaturase system specific to gymnosperms. The following hypothetical evolutionary sequence for the C₁₈ Δ6/Δ5-desaturase class in gymnosperm seeds is suggested: Δ6 (initial)→Δ6/Δ5 (intermediate)→Δ5 (final).     

Geometrical isomers of linolenic acid in low-calorie spreads marketed in France

The fatty acid compositions of 20 samples of low-calorie spreads marketed in France have been examined by gasliquid chromatography (GLC) of their isopropyl esters on a fused silica capillary column coated with 100% cyanopropyl polysiloxane. Spreads containing linolenic acid at a level of 2.3% or higher (5 out of the 20 samples under study) also containtrans- 18:3 isomers. These were identified, after fractionation of their isopropyl esters by thin-layer chromatography (TLC) on silica-gel plates impregnated with AgNO₃, by GLC on two capillary columns of different polarities and comparison of their equivalent chain lengths with those of authentic standards. Identifications were supported by GLC/mass spectrometry of the dimethyl esters resulting from ozonolysis in BF₃/methanol of the monoenes isolated by AgNO₃-TLC after hydrazine reduction of 18:3 isomers. 9c,12c,15t-18:3 and 9t,12c,15c-18:3 were found to be the most abundant 18:3 isomers in the spreads, with small amounts of 9c,12t,15c-18:3. These isomers occurred in the relative proportions 52–55, 41–42 and 4–6%, respectively. These proportions are independent of the origin of the sample. The tentatively identified 9t,12c,15t-18:3 also occurred in some instances. In 2 of the spreads, total geometrical isomers of linolenic acid accounted for 0.9–1% of the total fatty acids (up to 28% of the total 18:3n-3 fraction). The presence of 18:3n-3 geometrical isomers in the spreads is likely due to rapeseed or soybean oils that were deodorized under rather harsh conditions before these were blended with other fats or oils. Partial hydrogenation of these oils may also contribute to accumulation of the same linolenic acid isomers in the spreads.     

Anodic stripping voltametric cell for determination of copper and lead in atmospheric dust

Studies of air pollution by metals contained in dust particules usually require mineralization of a dust-collecting filter. This treatment introduces impurities into the sample. To avoid such contamination, an anodic stripping cell was constructed requiring no preliminary treatment of the sample filter. The cell uses a three-electrode amperometric system in differential pulse anodic stripping mode (DPAS). Solubilization of the metals from dust by a complexing agent, instead of the strong acid normally encountered in other methods, allows selective determination of metals according to their chemical form. With this cell, minimal handling of the collection filter and a large area mercury-coated vitreous carbon electrode located close to the sample filter (2 mm) lead to limits of detection as low as 0.15 μg of lead and 10 ng of copper. Precision is 2% for lead determination and 4% for copper determination (RSD).     

Multiple reactor testing of a synthetic sorbent for regenerative sulfur capture in fluidized bed combustion of coal

A new synthetic regenerable sorbent was developed as an alternative to limestone and dolomite for regenerative sulfur capture in fluidized bed combustion (FBC of coal. The sorbent consists of CaO (8-9 wt%) on a spherical 3 mm diameter γ-Al₂O₃ support. A shrinking unreacted core model (SURE2) is proposed to describe the sulfation process. Experiments have been carried out in a 12 mm internal diameter fixed bed reactor, a 0.05 m ID fluidized bed reactor and a thermobalance. The results obtained for all three reactors are in good agreement with the predictions of the SURE2 model.