Wax Mixtures Research Articles

Wheat Transcription Factor TaMYB60 Modulates Cuticular Wax Biosynthesis by Activating TaFATB and TaCER1 Expression.

Cuticular wax mixtures cover the epidermis of land plants and shield plant tissues from abiotic and biotic stresses. Although cuticular wax-associated traits are employed to improve the production of bread wheat, regulatory mechanisms underlying wheat cuticular wax biosynthesis remain poorly understood. In this research, partially redundant transcription factors TaMYB60-1 and TaMYB60-2 were identified as positive regulators of wheat cuticular wax biosynthesis. Knock-down of wheat TaMYB60-1 and TaMYB60-2 genes by virus-induced gene silencing resulted in attenuated wax accumulation and enhanced cuticle permeability. The roles of wheat fatty acyl-ACP thioesterase genes TaFATB1 and TaFATB2 in cuticular wax biosynthesis were characterized. Silencing wheat TaFATB1 and TaFATB2 genes led to reduced wax accumulation and increased cuticle permeability, suggesting that TaFATB1 and TaFATB2 genes positively contribute to wheat cuticular wax biosynthesis. Importantly, transcription factors TaMYB60-1 and TaMYB60-2 exhibit transcriptional activation ability and could stimulate the expression of wax biosynthesis genes TaFATB1, TaFATB2, and ECERIFERUM 1 (TaCER1). These findings support that transcription factor TaMYB60 positively regulates wheat cuticular wax biosynthesis probably by activating transcription of TaFATB1, TaFATB2, and TaCER1 genes.

Micromorphological and Chemical Characterization of Drimys winteri Leaf Surfaces: The Secondary Alcohols Forming Epicuticular Wax Crystals Are Accompanied by Alkanediol, Alkanetriol and Ketol Derivatives.

The cuticle is a hydrophobic coating of most aerial plant surfaces crucial for limiting non-stomatal water loss. Plant cuticles consist of the lipid polyester cutin and associated waxes with compositions varying widely between plant species and organs. Here, we aimed to provide a comparative analysis of the dark-glossy adaxial and pale-glaucous abaxial sides of Drimys winteri (Winteraceae) leaves. Scanning electron microscopy showed nanotubular wax crystals lining the entire abaxial side of the leaf (including stomatal pores), while the adaxial side had patches of mixed platelet/tubule crystals and smooth areas between them. Consecutive treatments for wax removal and cutin depolymerization revealed that the waxes were deposited on a cutin network with micron-scale cavities across the entire abaxial surface including the stomata pores, and on a microscopically smooth cutin surface on the adaxial side of the leaf. Gas chromatography coupled to mass spectrometry and flame ionization detection showed that the wax mixtures on both sides of the leaf were complex mixtures of very-long-chain compounds dominated by the secondary alcohol nonacosan-10-ol and alkanediols with one hydroxyl on C-10. It is therefore very likely that the characteristic tubular wax crystals of both leaf sides are formed by these alcohols and diols. Further secondary alcohols and alkanediols, as well as ketols and alkanetriols with one functional group on C-10, were identified based on mass spectral fragmentation patterns. The similarities between all these mid-chain-functionalized compounds suggest that they are derived from nonacosan-10-ol via regio-specific hydroxylation reactions, likely catalyzed by three P450-dependent monooxygenases with different regio-specificities.

Project ChemicalBlooms: Collaborating with citizen scientists to survey the chemical diversity and phylogenetic distribution of plant epicuticular wax blooms.

Plants use chemistry to overcome diverse challenges. A particularly striking chemical trait that some plants possess is the ability to synthesize massive amounts of epicuticular wax that accumulates on the plant's surfaces as a white coating visible to the naked eye. The ability to synthesize basic wax molecules appears to be shared among virtually all land plants, and our knowledge of ubiquitous wax compound synthesis is reasonably advanced. However, the ability to synthesize thick layers of visible epicuticular crystals ("wax blooms") is restricted to specific lineages, and our knowledge of how wax blooms differ from ubiquitous wax layers is less developed. Here, we recruited the help of citizen scientists and middle school students to survey the wax bloom chemistry of 78 species spanning dicot, monocot, and gymnosperm lineages. Using gas chromatography-mass spectrometry, we found that the major wax classes reported from bulk wax mixtures can be present in wax bloom crystals, with fatty acids, fatty alcohols, and alkanes being present in many species' bloom crystals. In contrast, other compounds including aldehydes, ketones, secondary alcohols, and triterpenoids were present in only a few species' wax bloom crystals. By mapping the 78 wax bloom chemical profiles onto a phylogeny and using phylogenetic comparative analyses, we found that secondary alcohol and triterpenoid-rich wax blooms were present in lineage-specific patterns that would not be expected to arise by chance. That finding is consistent with reports that secondary alcohol biosynthesis enzymes are found only in certain lineages but was a surprise for triterpenoids, which are intracellular components in virtually all plant lineages. Thus, our data suggest that a lineage-specific mechanism other than biosynthesis exists that enables select species to generate triterpenoid-rich surface wax crystals. Overall, our study outlines a general mode in which research scientists can collaborate with citizen scientists as well as middle and high school classrooms not only to enhance data collection and generate testable hypotheses but also to directly involve classrooms in the scientific process and inspire future STEM workers.

Optimization of organogels prepared with turpentine oil and wax mixtures via response surface methodology and determination of vaporization kinetic parameters.

The main aim of the study is to investigate the thermal, textural and vaporization behaviors of turpentine oil (representing essential oils) organogels prepared with wax mixtures (beeswax, BW; shellac wax, SHW) instead of a single wax. The second aim was to determine the optimum level of wax addition to minimize vaporization of volatiles using response surface methodology. Both weighing and thermogravimetric analyses showed that when the total wax concentration increased, the vaporization was decelerated. The variation of the hardness and melting point values depended on both wax types and amounts in the mixtures. Additionally, the kinetics of the vaporization of the volatile compounds at 37 °C were evaluated, and both first- and second-order reaction kinetic models fitted well for the vaporization with R2 values of 0.96-0.99. The organogelation increased the thermal stability and limited the release of volatiles. The multiple response optimization results showed that the melting point, the reaction rate constant and the weight loss of the organogels produced with 24.43% BW and 17.68% SHW were 44.40 °C, 4.00 × 10-3 day-1 and 30.02%, respectively. As a result, essential oil organogels produced with a wax mixture instead of a single wax can provide controlled release of volatiles as well as tailored texture and melting range. © 2024 Society of Chemical Industry.

Impact of binary mixtures of natural waxes in mechanical properties and microstructure of oleogels.

Solid fats are critical to obtaining a wide range of food texture and quality characteristics, but their consumption is strongly associated with higher cardiovascular disease risks. Structuring unsaturated oils with natural waxes into oleogels (OG) is an innovative solution to develop fat mimics with a healthier profile. Soy wax (SW), beeswax (BW) and carnauba wax (CW), have been used in binary mixtures of waxes, aiming to understand their interactions and influence on OG quality properties and microstructural characteristics. In the present study, OGs were produced using binary wax mixtures and analyzed for texture, color, smoke point, microstructure, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Wax combinations led to antagonistic (mixtures with SW) and synergistic interactions (BW/CW) based on their mechanical properties. At the microstructural level BW/CW blends showed a reduction in crystal size and with a more compact structure. XRD and FTIR spectra revealed a packing of orthorhombic perpendicular subcell for most OGs, whereas SW produced samples with an arrangement with β' crystals, characteristic of edible solid fats. Additionally, when compared to commercial beef fat, BW/CW mixtures showed similar quality attributes indicating that they could act as fat mimic. The combined analysis of microstructure, spectroscopic and mechanical properties enhanced the understanding of how the nature of the interactions between waxes and lipid phases impact in the final quality of the structured oils. The study's insights indicate that binary wax combinations can efficiently replace solid fats, offering healthier alternatives at the same time as preserving desired sensory characteristics. © 2024 Society of Chemical Industry.

Precipitated wax content and yield stress of model wax-oil mixtures determined by arrest of flow during cooling at fixed stress

To estimate yield stress and other rheological properties relevant to modeling of wax deposition in pipelines where flow is continuous, but stress varies across the pipe radius, model wax-oil mixtures are cooled at multiple cooling rates under constant shear stress until a temperature is reached, at which flow is arrested by gelation due to wax crystal formation. From these data, combined with a measurement of temperature-dependence of precipitated wax concentration by differential scanning calorimetry, an apparent yield stress σy, below which flow is arrested at each temperature, is related to the concentration of precipitated wax Cp and the cooling rate. Results are reported for multiple concentrations in oil of two independent wax mixtures: a many-component commercial wax mimicking the composition of field oil, and a simpler six-alkane mixture. These transient rheological data are fit to a pseudo “Herschel–Bulkley” constitutive equation from which it is found that the yield stresses obtained during flow under cooling are generally an order of magnitude, or more, lower than the yield stresses obtained in the previous work in flow at a comparable constant temperature after cooling in the absence of flow. We also find a strong decrease in the arrest temperature with a decreasing cooling rate, with no convergence even at the lowest cooling rate of 0.0625 °C min−1, indicating that under slower cooling, flow continues even under low stresses. The cooling-rate-dependent yield stress obtained in our study under constant stress provides a challenge to the recent models of gelation under flow stress and is of relevance to wax deposition in pipelines.

Wax appearance temperature under shear in methane-saturated mineral oil + paraffin wax mixtures: Effects of concentration and pressure

Increasing oil production from cold environments, such as offshore deep-water, has resulted in flow assurance issues due to wax deposition and hydrate formation. Understanding of the high-pressure flow properties of waxy oils is important to minimize blockages and related issues. However, the effect of pressure on wax appearance temperature (WAT) and viscosity of waxy oils is not widely studied due to the challenges of high-pressure rheology experiments. Here, a model waxy oil system was investigated using a high-pressure rheology from 0 to 1400 psig at 100 s−1. The focus was on paraffin wax in heavy mineral oil, and we examined wax concentrations of 5, 10, 15, and 20 wt%. First, waxy oils were saturated in methane, and then, temperature was decreased until wax appearance occurred. The findings revealed that wax concentration has a larger effect on WAT than pressure. At a constant pressure of 0 psig, WAT increases up to 13 °C when wax concentration increases from 5 to 20 wt%. Increasing pressure from 0 to 1400 psig results in up to 6 °C depression in wax appearance temperature for 20 wt% wax. The findings of the current study contribute to addressing flow assurance challenges in cold environments by enhancing the understanding of waxy oil rheology under methane-saturated, high-pressure conditions.

Evaluation of paper coated with cationic starch and carnauba wax mixtures regarding barrier properties

Studies of single-use packaging have aimed to replace materials obtained from non-renewable sources with biodegradable materials from renewable sources in response to environmental concerns. Their barrier properties maximize shelf life and product safety. To provide such green packaging, this work aimed to describe the chemical, physical, morphological, and barrier properties of bilayer coatings made from mixtures of cationic starch (S) and carnauba wax (W) on kraftliner paper (86 ± 1 g/m²). Two coating layers (15.0 ± 0.5 g/m²) of both materials in different proportions were compared to uncoated paper and doublewet-and-dry paper. The addition of cationic starch to carnauba wax raised the melting point of the wax, preventing it from completely entering the paper's pores but instead producing a layer on top of them. The hydroxyl groups present in coated paper S contributed to its hydrophilicity, showing a high Cobb value, absorbing 153 g/m² more water than control samples. Further, the mixtures showed higher hydrophobicity than the cationic starch-treated samples, with a high-water contact angle (100 ± 4°), similarly found for the W treatment. In addition, mixtures showed 0.35°/s less wettability than the W treatment. In terms of mechanical strength, the lower tensile strength and Young's modulus of the coated sheets brought on by hornification appear to have been predominantly caused by water in the suspensions. The addition of carnauba wax to the cationic starch decreased the resistance of coated papers to oil. However, there was an improvement in the water barrier by decreased water absorption and wettability and an increase in water contact angle.

Spray coating of edible insect waxes for liquid food packaging

In this study, insect waxes (Beeswax and Shellac wax) were spray-coated onto paper, cups, and bowls to achieve surface hydrophobicity for packaging applications. The thin coatings of wax mixtures with different ratios of waxes were employed at various annealing temperatures and studied in detail for the thermal, chemical, surface, and barrier properties of 20 coated papers. SEM confirmed the presence of multi-structured wax particles on the surface of coated papers only when annealed up to 80 °C (at 100 °C complete melting of wax particles occurred), where increasing Shellac wax in the wax mixtures resulted in large aggregates of wax particles on the paper. FTIR confirmed Beeswax with shorter fatty acid chains, comparing Shellac wax with longer fatty acid chains. Additionally, DSC confirmed a lower melting point for Beeswax, comparing Shellac wax with the higher melting point. The robustness of waxes after annealing was evident from the tape and crinkle tests. The spray-coated paper with insect wax mixture showed good repellency towards different food simulants, such as water, acetic acid, ethanol, octane, and several food products, as measured using contact angles. Lowered water absorption was noted for coated pulp-based bowls. The coating also showed self-cleaning or anti-fouling properties.

Hardness, plasticity, and oil binding capacity of binary mixtures of natural waxes in olive oil

In this study, olive oil oleogels structured with less than 4% binary blends of sunflower wax (SFW), rice bran wax (RBW), candelilla wax (CDW), and beeswax (BW) were characterized. Among the different binary wax oleogels, samples structured with 3% (w/w) of binary mixtures of SFW and RBW, as well as binary mixtures of CDW and BW, displayed a high oil binding capacity relative to any other mixtures. Moreover, in some binary wax oleogels, back extrusion hardness and elastic constant were significantly higher than that of oleogels prepared using the individual waxes. This was interpreted as a synergism between these waxes. Image analysis of oleogel brightfield micrographs indicated that the samples with a higher elastic constant had a lower box-counting fractal dimension and larger crystals, suggesting that this increase in the elastic constant was a consequence of the lower fractal dimension of the wax crystal network, in agreement with established fractal structural-mechanical models for van der Waals colloidal networks. The crystal structure of the individual waxes and their blends showed orthorhombic perpendicular subcell packing arrangements, which did not change upon mixing, suggesting this length scale did not play a role in the observed synergism. The melting point of binary mixtures of waxes in olive oil was in the range of 43.2 °C to 67.4 °C and pseudo-ideal mixing behavior was observed. The hardness and plasticity (brittleness) of the 2% and 3% binary wax mixtures in olive oil characterized using back extrusion, were similar to those of a commercial soft margarine, suggesting a potential use of the wax oleogels as margarine or spread replacers.

Shear alters wax appearance in mineral oil + paraffin wax mixtures

Shear alters wax appearance in mineral oil + paraffin wax mixtures

Molecular dynamics simulation of the n-octacosane-water mixture confined in hydrophilic and hydrophobic mesopores: The effect of oxygenates

Wax and water mixtures are the main products of the Gas-To-Liquids (GTL) process through the Fischer-Tropsch synthesis (FTS), along with relatively small quantities of oxygenated compounds such as alcohols. It has been established that water production in high concentrations leads to phase segregation inside the catalyst support pores. Excess water conditions are considered responsible for sintering of catalytic nanoparticles, which reduces catalyst lifetime and increases GTL operational cost. Apart from the effects of increased water concentration in wax – water FTS mixtures, the presence of oxygenates has not been studied at the molecular level. Moreover, the effect of the surface support chemistry on the wax – water mixture inside catalyst pores is essential in understanding mixture phase behavior. All these open questions are of significant interest for the petrochemical industry. The present study focuses on simulating by means of Molecular Dynamics (MD) the n-octacosane (n-C28) – water mixture inside titanium dioxide (TiO2) and silicon carbide (SiC) mesopores at low-temperature FTS conditions (473.15 K). The presence of small alcohols such as methanol and ethanol on the n-C28 – H2O mixture's phase behavior was also evaluated. The united atom TraPPE (TraPPE-UA) force field was used for n-C28 and the alcohols, while the SPC/E was used for water. Catalyst support atoms were modeled as Lennard-Jones spheres (charged or neutral) at fixed positions. Our simulations show that inside TiO2, water molecules organize into two discrete layers on the TiO2 surface, with n-C28 occupying the pore center; mixture phase separation is completely reversed inside the SiC pore. In both cases, alcohol addition does not influence either n-C28 or H2O distribution inside the pores. Furthermore, we examine the hydrogen bonds formed between water molecules and how these are influenced upon alcohol addition and confinement. Finally, through the calculation of lateral diffusion coefficients, we provide insights on the mobility of the individual n-C28 – H2O mixture components inside the pores considered.

Chemical composition of the cuticular membrane in guava fruit (Psidium guajava L.) affects barrier property to transpiration

The cuticular membrane covering almost all aerial plant organs has a primary function in limiting uncontrolled water loss. The guava fruits were collected and this work was done to study the potential contribution of cuticular chemical composition to fruit transpiration after harvest. The detailed cuticular chemical composition, based on gas chromatography together with mass spectrometry, and the transpiration rate determined gravimetrically in guava fruit were characterized in the present study. The predominant wax mixtures were fatty acids and primary alcohols with homologous series of C16–C33, as well as various pentacyclic triterpenoids with abundant amounts of ursolic acid, maslinic acid and uvaol. The most prominent cutin compounds were C16 and C18‒type monomers dominated by 9(10),16-diOH-hexadecanoic acid and 9,10-epoxy-ω–OH–octadecanoic acid, respectively. Relatively high water permeability with a value of 5.1 × 10−4 m s−1 was detected for guava fruit. The lower efficiency of the cuticle as barrier to transpiration in guava fruit, as compared to that of other reported fruits, leaves, and petals, was seemingly related to the relatively short average chain-length of acyclic compounds in wax mixtures. These findings provide useful insights linking the chemical composition of the cuticular membrane that covers plant organs to putative physiological roles.

Exogenous hormones influence Brassica napus leaf cuticular wax deposition and cuticle function.

BackgroundCuticular waxes cover plant surface and play important roles in protecting plants from abiotic and biotic stresses. The variations of wax deposition and chemical compositions under changing environments have been shown to be related to plant adaptations. However, it is still not clear whether the wax depositions could be adjusted to increase plant adaptations to stressed conditions.MethodsIn this study, exogenous methyl jasmonate (MeJA), the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and salicylic acid (SA) were applied to test their effects on cuticular wax deposition in two Brassica napus cultivars, Zhongshuang 9 (ZS9, low wax coverage ) and Yuyou 19 (YY19, high wax coverage). Next, we measured the water loss rate and the transcriptional expression of genes involved in wax biosynthesis as well as genes related to disease defense.ResultsSeven wax compound classes, including fatty acids, aldehydes, alkanes, secondary alcohols, ketones, and unbranched as well as branched primary alcohols, were identified in B. napus leaf wax mixtures. MeJA, SA and ACC treatments had no significant effect on total wax amounts in YY19, whereas ACC reduced total wax amounts in ZS9. Overall, hormone treatments led to an increase in the amounts of aldehydes and ketones, and a decrease of secondary alcohol in ZS9, whereas they led to a decrease of alkane amounts and an increase of secondary alcohol amounts in YY19. Concomitantly, both cultivars also exhibited different changes in cuticle permeability, with leaf water loss rate per 15 min increased from 1.57% (averaged across treatments) at 1.57% (averaged across treatments) at 15 min to 3.12% at 30 min for ZS9 (except for ACC treated plant) and decreased for YY19. MeJA-treated plants of both cultivars relatively had higher water loss rate per 15 min when compared to other treatments. Conclusion. Our findings that B. napus leaf wax composition and cuticle permeability are altered by exogenous SA, MeJA and ACC suggest that the hormone treatments affect wax composition, and that the changes in wax profiles would cause changes in cuticle permeability.

Physical-Chemical Characterization and Thin Layer Chromatographic Comparison of a Local Propolis with the Mangifera indica Resin

Mango (Mangifera indica) is an abundant tree of Cuban flora that is known for many healing properties and a deposit of bees as a source of raw materials for the propolis production. This work aimed to determine if the resin of mango felled bark was used by honeybees in the elaboration of a specific type of propolis. This could be possible by qualitatively comparison of its samples with the mango resin and the quality of this propolis through its physicochemical characteristics. To do this, propolis was collected and hydroalcoholic extracts were prepared. From this, botanical origin was determined by the technique of thin layer chromatography. Humidity, oxidation index, wax, resin and mechanical mixtures were evaluated from raw material. Results demonstrated that the samples of propolis collected presented a chromatographic profile similar to mango resin. In the samples of propolis, it was determined that quercetin and mangiferin are present in their qualitative composition of secondary metabolites. On the other hand, the mango propolis satisfies the requirements established by international regulations for good quality propolis in terms of humidity, oxidation index and mechanical mixtures.

Concentration dependent cholesteryl-ester and wax-ester structural relationships and meibomian gland dysfunction

BackgroundWith dry eye, the ratio of cholesteryl ester (CE) to wax ester (WE) decreases substantially in meibum, but the functional and structural consequences of this change are speculative. The aim of this study is to confirm this finding and to bridge this gap in knowledge by investigating the effect of varying CE/WE ratios on lipid structure and thermodynamics. MethodsInfrared spectroscopy was use to quantify CE and WE in human meibum and to measure hydrocarbon chain conformation and thermodynamics in a cholesteryl behenate, stearyl stearate model system. ResultsThe CE/WE molar ratio was 36% lower for meibum from donors with dry eye due to meibomian gland dysfunction compared with meibum from donors without dry eye. CE (5 mol %) dramatically increased the phase transition temperature of pure WE from -0.12 °C to 63 °C in the mixture. Above 5 mol % CB, the phase transition temperature increased linearly, from 68.5 °C to 85 °C. In the ordered state, CE caused an increase in lipid order from about 72% trans rotamers to about 86% trans rotamers. Above 10% CE, the hydrocarbon chains were arranged in a monoclinic geometry. ConclusionsThe CE/WE is lower in meibum from donors with dry eye due to meibomian-gland dysfunction. Major conformational changes in the hydrocarbon chains of wax and cholesteryl ester mixtures begin to occur with just 5% CB and above. General significanceCE-WE interactions may be important for in understanding lipid layer structure and functional relationships on the surface of tears, skin and plants.

Chemical Composition of the Cuticle Membrane of Pitaya Fruits (Hylocereus Polyrhizus)

This study comprehensively analysed the chemical composition of the cuticle in pitaya fruits. The total coverage amount of the waxes versus cutin monomers accumulated at a ratio of 0.6, corresponding to masses per unit of 30.3 μg·cm−2 and 50.8 μg·cm−2, respectively. The predominant wax mixtures were n-alkanes in homologous series of C20–C35, dominated by C31 and C33; as well as triterpenoids with an abundant amount of uvaol, lupenon, β-amyrinon, and β-amyrin. The most prominent cutin compounds were C16- and C18-type monomers, in which 9(10),16-diOH-hexadecanoic acid and 9,10-epoxy-ω-OH-octadecanoic acid predominated, respectively. The average chain length (ACL) of aliphates in pitaya fruit cuticle (30.5) was similar to that estimated in leaf waxes, and higher than that in most of the fruit and petal waxes that have been reported. We propose that the relatively high ACL and wax/cutin ratio might enhance the cuticular barrier properties in pitaya fruit cuticle to withstand drought.

Physical Properties of Beeswax, Sunflower Wax, and Candelilla Wax Mixtures and Oleogels

AbstractTo be able to tailor and optimize the physical properties of oleogels for various food applications, more information is needed to understand how different gelators interact. Therefore, the objectives of this study were to evaluate the interactions between binary mixtures of beeswax (BW), candelilla wax (CLW), and sunflower wax (SFW) in pure form as well as in 5% wax oleogels made with soybean oil, in terms of their crystallization and melting properties, crystal morphology, solid fat content, and gel firmness. CLW:BW mixtures had eutectic melting properties, and oleogels from these mixtures with 40:60 to 90:10 CLW:BW were firmer compared to oleogels made with one wax. The main components in SFW and BW appeared to cocrystallize or crystallize at the same temperature, but nonlinear changes in melting point and solid fat content profile of oleogels prepared with the mixed waxes indicated that SFW dominated oleogel formation. In addition, oleogels prepared with mixtures of SFW and BW had lower firmness compared to oleogels prepared with one wax, indicating an incompatibility between the two waxes. The main wax components in SFW and CLW never cocrystallized, and low levels of CLW appeared to prevent SFW from forming a crystalline platelet network. This resulted in low firmness of oleogels made from mixtures of 90:10 to 60:40 SFW:CLW compared to oleogels prepared with one wax. However, the firmest oleogels of all mixtures were made from 10:90 SFW:CLW. Changes in gel firmness and melting properties with mixed wax oleogels were likely to be due to changes observed in the crystal size and morphology. In addition, the firmest gels were shown to result from mixtures that were predicted to have >40% hydrocarbon content, and a high hydrocarbon to wax ester ratio, but minor components such as free fatty acids and fatty alcohols may have also influenced firmness.

Coverage and composition of cuticular waxes on the fronds of the temperate ferns Pteridium aquilinum, Cryptogramma crispa, Polypodium glycyrrhiza, Polystichum munitum and Gymnocarpium dryopteris.

The cuticular waxes sealing plant surfaces against excessive water loss are complex mixtures of very-long-chain aliphatics, with compositions that vary widely between plant species. To help fill the gap in our knowledge about waxes of non-flowering plant taxa, and thus about the cuticle of ancestral land plants, this study provides comprehensive analyses of waxes on temperate fern species from five different families. The wax mixtures on fronds of Pteridium aquilinum, Cryptogramma crispa, Polypodium glycyrrhiza, Polystichum munitum and Gymnocarpium dryopteris were analysed using gas chromatography-mass spectrometry for identification, and gas chromatography-flame ionization detection for quantification. The wax mixtures from all five fern species contained large amounts of C36-C54 alkyl esters, with species-specific homologue distributions. They were accompanied by minor amounts of fatty acids, primary alcohols, aldehydes and/or alkanes, whose chain length profiles also varied widely between species. In the frond wax of G. dryopteris, C27-C33 secondary alcohols and C27-C35 ketones with functional groups exclusively on even-numbered carbons (C-10 to C-16) were identified; these are characteristic structures similar to secondary alcohols and ketones in moss, gymnosperm and basal angiosperm waxes. The ferns had total wax amounts varying from 3.9 μg cm-2 on P. glycyrrhiza to 16.9 μg cm-2 on G. dryopteris, thus spanning a range comparable with that on leaves of flowering plants. The characteristic compound class compositions indicate that all five fern species contain the full complement of wax biosynthesis enzymes previously described for the angiosperm arabidopsis. Based on the isomer profiles, we predict that each fern species, in contrast to arabidopsis, has multiple ester synthase enzymes, each with unique substrate specificities.

On the properties and application of beeswax, carnauba wax and palm fat mixtures for hot melt coating in fluidized beds

Coating of particulate solids is a well-known process within the chemical, pharmaceutical and food industry. Most of these industries use it to achieve a defined product behavior. Melt-coatings, in this paper beeswax, carnauba wax and palm fat, are more difficult to apply compared to solvent-based coatings because of the complex solidification behavior.This contribution focuses on the experimental investigation of the crystallization process. The thermal crystallization behavior of mixtures of beeswax, carnauba wax and palm fat is investigated to determine the processability and the achievable coating quality prior to lab trials. Mixing of the melts results in a broadening of the crystallization temperature range, making the process more challenging. The rheological behavior in the phase transition of different mixtures shows a rather sudden change in the flowability contrary to the extended thermal solidification. The sudden change is a consequence of the linking of the appearing crystals, which was visualized at different solidification temperatures by polarization microscopy. The Martens hardness of the solidified material was adjusted by blending between 2 and 17 N/mm2. The coating was applied in a lab-scale fluidized bed based on parameters determined from the characteristics. A micro-computed tomography image shows a closed coating of varying thickness. It was possible to predict the coating process with these natural products out of the material properties, and adapt them by blending. Furthermore the results of this contribution show that there is a gap between the pure processabilty and the achievable coating quality.