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AIR3-CT94-2480
Crambe abyssinica, a comprehensive programme - Workshop - Part 4 - Utilisation |
Crambe produces an oil with a very high erucic acid content, and this composition determines some particular physico-chemical properties such as a high viscosity and a high smoke point. These characteristics, linked to the excellent biodegradability and the low toxicity of vegetable oils, make crambe oil very interesting in some non-food fields. In this work we report the results of some tribological analyses carried out in co-operation with some private industries to confirm the interesting properties of this product as biolubricant and in lipochemistry. In particular, for utilisation in steel casting and hardening, the heat removal and cooling rates of native and modified (without the unsaponifiable matter) crambe oil are reported and compared with some other vegetable and synthetic oils. The results showed that crambe oil has an higher capability in heat removal, and this is a very important characteristic for an utilisation as lubricant. For an utilisation as an hydraulic fluid, the Falex test and the main physico-chemical properties of a new formulation based on crambe oil was compared to a commercial one based on canola oil. The performance of crambe formulation indicates some interesting characteristics for hydrodynamic and boundary lubrication and as an hydraulic fluid. Finally, the very high long chain fatty acid content suggests some interesting possibilities for utilisation in the lipochemistry industry of the crambe fatty acids obtained after saponification. The main characteristics of crambe oil are discussed and compared to the animal oil at moment used in this field and the results show clearly that crambe oil can substitute fish oil from a technological point of view. This utilisation seems extremely interesting not only due to the higher quality of crambe oil but also for some advantages in commercialisation and stockage.
Friction (slip) and adhesion (blocking, mould release) are serious problems when processing a number of common plastics. Fatty acid amides are used extensively in polyolefin and other polymers to modify their surface properties alleviating these troublesome problems and allowing their use in a number of packaging applications. High friction in particular is a problem as polyethylene and polypropylene films would not be usable in high speed packing line operations (e.g. bread packaging). Fatty acid amides have been used as slip additives since the 1950s and received FDA approval for food use around this time. Oleamide and stearamide were first used for reduction of friction and blocking respectively, however, erucamide and behenamide have enjoyed the highest growth due to their superior performance. Amides work by migrating from the body of the polymer matrix to the surface where layers are formed. Slip is thought to occur along these layers thus amides act as 'external' lubricants. The advantage of this mode of action is that very small amounts are required (typically 500 - 2000 ppm in film) and amide is present at the surface in low concentrations early after extrusion. This allows easier surface treatment and printability than if a non-migrating additive or a coating process is used. Unsaturated primary amides show good slip properties whereas saturated amides have very poor slip characteristics and are better used as anti-blocking agents. Shorter chain amides are faster migrating in most polymers and are particularly useful where the matrix is highly crystalline. However they tend to be less stable and more volatile at high temperatures which limits their usage. Thus erucamide is usually preferred over oleamide for reducing friction in polypropylene even though it is slower acting. The main source of fatty acids for the production of erucamide is High Erucic Rape Oil (HERO) although alternative sources are being actively pursued (e.g. Crambe abyssinica, Brassica carinata, etc.). However, care must be taken in the use of these materials because, even after processing, there may be differences in the lipid profile which result in changes in performance.
Adjuvants are 'tank-mixed' with herbicides to improve the retention and penetration of the herbicide active ingredient; typical adjuvants include, surfactants and oil emulsifiable concentrates (ECs). Crambe oil was emulsified with 10 percent Atlox 3400B, a blend of anionic and nonionic surfactants. Its performance was judged by its effect compared with some commercial standards on retention and herbicide activity. Retention was measured by applying an aqueous solution of sodium fluorescein using a laboratory track sprayer fitted with an even-spray nozzle and calibrated to deliver 200 l ha l. The target plants were wheat and beans with 6 and 4 leaves, respectively. After droplet evaporation, fluorescein was recovered from excised foliage and measured by spectrofluorimetric assay. Neither emulsified Crambe oil nor the commercial standards increased retention on beans compared with water alone. Retention on the water-repellent wheat was enhanced by all the adjuvants. Retention was concentration-dependent for the oil-based adjuvants and appeared to be related to emulsifier content. The performance of Crambe EC was significantly better than that of the mineral oil-based EC(Fizol 11E) but less effective than one based on ethyl oleate (Vicchem EOP). However, none of the oil-based adjuvants matched the efficacy of the surfactants and polymeric adjuvants tested. Effectiveness of the adjuvants on the performance of the graminicide, quizalofop, was assessed by spraying as described earlier and recording foliage fresh weights. Quizalofop at 0, 5, 10, 20, 40 and 80 percent of the recommended dose was applied to Avena sativa cv. Craig at the 4-5 leaf stage. Crambe EC and a mineral oil EC (Actipron) were applied alone and mixed with herbicide at 1.0 and 2.0 percent of spray carrier volume (200 litres per ha). The oil ECs, Atlox B plus herbicide and quizalofop alone had no effect. Both Crambe EC and Actipron enhanced quizalofop activity significantly at 10 percent of the recommended dose and above with little difference between them. When the same treatments were applied to drought-stressed plants, 1 percent Crambe EC tended to be less effective than 1 percent Actipron, while 2 percent Crambe EC was slightly better than 1 percent Actipron. Similar trends were observed when sprayed plants were subjected to simulated rain one hour after herbicide application. The above results on spray retention and quizalofop activity suggest that Crambe EC performs as well as commercially available mineral- and plant-derived oil Ecs.
Crambe abyssinica is considered to be a very promising new oil crop
because of both its agronomic performance and the specific properties of its
oil. However for a successful introduction of this crop, applications of another
major component of the seed, i.e. proteins, could well be of decisive
importance. Little is known about the suitability of Crambe proteins for
applications with a higher added value, both food and non-food. Therefore, the
aim of this research is
a) to develop an isolation procedure for the
proteins and
b) to study their functional and biochemical properties.
After
dehulling and defatting, the protein content of the meal was 38 percent. About
66 percent of the proteins could be extracted at alkaline pH. From the extract
about half of the proteins could be recovered by isoelectric precipitation. The
proteins remaining soluble could be concentrated by ultrafiltration with a
recovery of about 65 percent. The process resulted in two fractions, i.e. an
isoelectric precipitate (Fraction I; protein content 78 percent) and a retentate
(Fraction II; protein content 87~o) which together account for 50 percent of the
proteins present in Crambe meal. Functional properties of both fractions have
been assessed. As expected, the solubility of Fraction I showed a minimum in the
isoelectric pH range. However, Fraction II was soluble (> 80 percent) over
the whole pH range tested (pH 3-11). The foaming properties of Fraction I were
better than those hen's egg white only at pH 9, whereas those of Fraction II
were superior at almost every pH tested. Only at alkaline pH, both fractions
showed good emulsifying properties (both stability and activity). Addition of
NaCl did not affect the properties (solubility and foaming) of Fraction II, but
improved those of Fraction I. Gel permeation chromatography (GPC3 showed that in
Fraction I high molecular weight proteins (>669 kDa) are present; the
proteins in Fraction II had lower molecular weights. SDS-PAGE (after reduction)
revealed that both fractions consist of proteins having molecular weights below
40 kDa. This indicates that the larger proteins found upon GPC are build up from
subunits. SDS-PAGE also revealed distinct differences in protein composition of
the two fractions.
Epi-progoitrin, the major glucosinolate of Crambe abyssinica, can be readily extracted from defatted crambe meal. A simple biotechnological process using immobilized myrosinase (Leoni et al., 1994) allows a high-yielding chemo- and stereocontrolled transformation of epi-progoitrin into glucose-free epi-goitrin, which was shown - using a novel chiral discrimination methodology involving a structurally modified b-cyclodextrin (Gosnat et al., 1995) - to be obtained in enantiomerically pure form. Figure Many regio- and stereochemically-controlled chemical modifications of epi-goitrin can be carried out in order to offer a wide array of bio-active stereo-defined molecules. As a member of the heterocyclic family 1,3-oxazolidine-2-thiones, epi-goitrin displays fascinating functional features: i) an ambident nucleophilic character ii) a chiral center (C-5) iii) a C-5 branched vinyl moiety. Diversified examples will be shown, including regiospecific N-acylations aimed at developing new systemic herbicides (Daubos et al., 1997) and S-alkylations serving as a prelude to the Eschenmoser reaction and other stereocontrolled rearrangements. With regard to molecular valorization of epi-goitrin, the chemical modification approach appears to be highly promising: after a preliminary chemical reactivity screening and diversified testing (stereochemical, technical, biological...) of the new compounds elaborated, investigation can be extended to the use of lower-cost (weaker degree of purity) chemo-enzymatically-produced material. As a consequence of the foregoing results, the status of crambe meal should evolve from troublesome waste towards profitable starting material for the production of enantiomerically pure fine chemicals.
References
Gosnat M., Djedaini-Pilard F., Perly, B., 1995. Etude par RMN de la
reconnaissance chirale par des cyclodextrines modifiees,J. Chem. Phys. 92,
1777-1781.
Leoni O., Marot C., Rollin P., Palmieri S., 1994. Preparation of
(5R)-5-vinyloxazolidine- 2-thione from natural epiprogoitrin using immobilized
myrosinase, Tetrahedron: Asymmetry 5, 1157-1160.
Daubos P., Grumel V., Iori R.,
Leoni O., Palmieri S., Rollin P., 1997. Crambe abyssinica meal a
starting material for the production of enantiomerically pure fine chemicals,
Ind. Crops Prod., in press
The objective of this study was exploitation of potentials of the Crambe abyssinica hull for applications in pulp and paper production, composites and cellulose derivatives. The first part of the study was focused on alternative process of cellulose isolation based upon energy saving and environmental impact reduction. For this purpose steam explosion and organosolv treatments were used. Crambe abyssinica cellulose was then characterised by SEM microscopy, X-ray diffraction, FTIR and solid NMR spectroscopy. Steam explosion treatment carried out at 200-C for 2 minutes induced a high fractionation of starting hull resulting in 4 fractions, the first soluble in water, the second in ethylacetate, the third in dioxane/water, being the solid fraction a mixture of cellulose and lignin insoluble in dioxane/water. Cellulose was isolated by chlorite treatment and purified by NaOH (1 percent w/v) at reflux. Organosolv treatment carried out in acetone/water (1:1) at 170 degrees C for 120 min in the presence of NaOH (2 percent w/w) and sulphite (16 percent w/w) was less effective in the fractionation of the polymer components of Crambe abyssinica hull. Chlorite and soda treatments at reflux were needed to obtain pure cellulose. The characterisation of Crambe abyssinica cellulose by X-ray, FTIR and NMR techniques evidenced a highly pure cellulose with a low crystallinity index (40 percent) in comparison with other annual plants, and thus useful for the preparation of cellulose derivatives. While the degree of polymerisation (600-800) is enough for this latter purpose, it is fairly low for the utilisation in papermaking. For this reason, in the second part of the study preliminary experiments were carried out by using Crambe abyssinica cellulose in mixture (20 percent) with conventional fibres for the preparation of paper samples.
Crambe oil has been tested as a possible adjuvant in fungicide formulations. This a new vegetable oil, rich in erucic acid and extracted from Crambe abyssinica, was formulated with POE-castor oil and a PEG-condensate (advised by ICI). Crambe oil improves slightly the wettability of Tilt 250 EC spray droplets, without increasing the risk of coalescence or run off. Propiconazol, the active ingredient (a.i.) of Tilt, penetrated faster into the leaf surface when crambe oil was added to the spray liquid and was concentrated in the cuticle of the leaf surface. A rather limited concentration of propiconazol was thus found in the inner leaf tissue. The transport process of propiconazol across the inner leaf compartments was influenced in a positive way by the addition of crambe oil to the spray liquid (Tilt). No fungicide action was observed when pure crambe oil was applied to an "in vitro" Botrytis cinerea culture. When added to a Tilt spray liquid, a small antagonistic effect was noticed. Crambe oil didn't show phytotoxic effects on germination and growth of wheat plants (Minaret). The phytotoxic side effects of the Tilt spray liquid decreased slightly when crambe was added. The results are promising but not fully convincing. It should be noted that the formulation of crambe oil can still be improved for instance by modifying the oil (alkyl or butyl esters) or by using other emulsifiers . An other aspect is that the results for Tilt spray liquid are not representative for all the fungicide spray liquids on the market. There is still a lot of trial and error research needed before final conclusions can be drawn.
Ester derivative of fatty acids are increasingly considered by industries in the fields of lubrication, surfactants, plastic materials, plant protection. This is particularly true for sectors which are in direct connection with consumers because of health and environment reasons. Esters derivatives of seed oils have the advantage to be synthesised from renewable resources and can be expected to be easily biodegradable, non-irritating and non-toxic. In plant protection, it is long known that methyl esters of seed oils increase the efficacy of several herbicides and some of them are used as co-formulants or tank-mix adjuvants. In the present study, we examined the influence of erucic acid esters on the foliar penetration of herbicides. Two series were studied: esters of glycerol (monoglycerides) and esters of neopentylpolyols with erucic acid. Condensation of erucic acid with glycerol was catalysed by a recyclable Amberlite A 26 anionic resin. This procedure yielded directly glycerol monoerucate by an eco-compatible process. Partial or total esters of neopentylpolyols were synthesised by means of a controlled reaction involving acidic polyesterification of erucic acid with pentaerythritol, trimethylolpropane and hydroxypivalate of neopentylglycol. The influence of glyceryl erucate on the foliar penetration of the herbicides phenmedipham and 2,4-D was studied on barley (Hordeum vulgare), cleavers (Galium aparine) and pea (Pisum sativum). On all species, glyceryl erucate could compare to glyceryl oleate as enhancer of phenmedipham foliar penetration and on barley and cleavers it proved to have an action comparable to methyl oleate, already used as co-formulant for herbicides or as tank-mix adjuvant. On all species, glyceryl erucate could compare to glyceryl oleate and methyl oleate as enhancer of 2,4-D foliar penetration. The promoting influence of esters of erucic acid and neopentylpolyols on the foliar penetration of the herbicide phenmedipham was studied on barley. An influence of the degree of esterification was observed in each series. With pentaerythritol, the di-ester was more potent than the mono, tri and tetra -esters, which had similar effects. With trimethylolpropane, the mono and di-esters had similar influence, which was higher than the triester. With hydroxypivalate of neopentylglycol, the di-ester increased phenmedipham penetration to a higher extent than the mono-ester. However all esters of erucic acid and neopentylpolyols increased foliar penetration of phenmedipham to a lesser extent than methyl oleate. These results show that erucic acid derivatives show some promise in the formulation of herbicides.
Myrosinase from Crambe abyssinica has been studied less than those of other cruciferous seeds such as Sinapis alba and Brassica napus. We evaluated total and soluble myrosinase activity of eight defatted meals obtained from different C. abyssinica cultivars (Belann, Belenzian, Meyer, Mario, C-29, Cebeco 9402, Cebeco 9404 and Indy) using the pH-Stat method, which is the most suitable technique for assaying myrosinase activity in heterogeneous solid-water systems (1). Total myrosinase activity of C. abyssinica cultivars, assayed with epi-progoitrin (EPRO) as a substrate, ranged from 213 U/g (C-29) to 484 U/g (Cebeco 9404). Nevertheless, when the assays were carried out with sinigrin (SIN) as a substrate, the values of myrosinase activity were about seven times lower, ranging from 35 U/g (C-29) to 68 U/g (Cebeco 9404). On the other hand, S. alba defatted meal showed similar total myrosinase activity with EPRO and SIN: the average value was 115 U/g. It is important to emphasise that soluble myrosinase activities of C. abyssinica samples, evaluated with EPRO, were very low (5-9 U/g). In addition, none of the following glucosinolates, sinalbin, glucotropaeolin, glucorafenin and rapeseed glucosinolates (in which progoitrin, isomer of EPRO, prevailed) gave total myrosinase activity values comparable to those obtained with EPRO. The optimum pH of crambe myrosinase determined using EPRO, was around 6.5. This datum is very close to that found for myrosinase from S. alba (2). In addition, we determined the effect of temperature on EPRO and SIN hydrolysis rates. The optimum temperature of crambe myrosinase activity was 37 degrees C for EPRO and 55 degrees C for SIN. The main results of this work are: 1) solubility of crambe myrosinase in aqueous extracts is very low; 2) bound myrosinase appears to be highly specific catalyst for EPRO. At 37 degrees C, the hydrolysis rate of EPRO (the natural substrate present in crambe meal) is seven times higher than others GLs. The results of this study suggest that crambe could contain, in addition to myrosinase, a labile cofactor, specific for EPRO catalysed-hydrolysis reaction.
References
1. Palmieri, S.; Iori, R.; Leoni, O.; J.
Agric. Food Chem. 1987, 35, 617-621
2. Iori, R.; Rollin, P.; Streicher, H.;
Thiem, J.; Palmieri, S.; 1996 FEBS Letters 385, 87-90
Continuing our researches under the Italian PRisCA (Research Project on Altemative Cultures) project we studied the possibility to use Crambe abyssinica oil as a starting material for synthetic lubricants. In this paper the procedures for the preparation of monoesters from methyl-, ethyl-, isopropyl- and 2-ethylhexil alcohol as well as diesters from neopentyl glycol, triesters from trimethylol propane and tetraesters from pentaerhytritol are described. The different reactions have been set up using free fatty acids, methylesters and crambe oil as a starting material. All reactions have been carried out in a solvent-free medium, using normally available catalysts and in experimental conditions which can be easily scaled up to industrial level. All the obtained products along with the refined Crambe abyssinica oil used as a reference have been analysed in their main characteristics like viscosity, viscosity index, cold behaviour, oxidative and hydrolytic stability. Values between 5.8 and 78.7 square mm/sec for 40 degrees C viscosity have been obtained while pour point ranges, on pure products, between +3 and -27 degrees C. The products obtained have a very good hydrolytic stability, while the oxidative one, because of the presence of double bonds in the fatty acids molecule, is reduced and this fact can represent a limit for some technical applications. Results of application tests like four balls machine and Noack test are reported. In this case the known superiority of synthetic esters is confirmed. The complete set of data shows that starting from Crambe abyssinica oil it is possible to obtain several different products covering a wide range of properties and different applications. Furthermore in some cases the chemical modification of native crambe oil results in a greater thermal and hydrolytic stability and also the tribological properties are improved. Taking into account of the different properties of esters, the application field of these product can be found in two stroke engines, as hydraulic and metalworking fluids and for chain saving applications.
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