Wax analysis of vegetable oils using liquid chromatography on a double-adsorbent layer of silica gel and silver nitrate-impregnated silica gel

A chromatographic method is described to measure the crystallizable wax content of crude and refined sunflower oil. It can also be applied to any other vegetable oil. The preparative liquid chromatography step on a glass column containing a silica gel adsorbent superimposed upon a silver nitrate-impregnated silica gel support is used to isolate a wax fraction which is then analyzed by gas chromatography. The recovered wax fraction contains, in addition to the crystallizable waxes, hydrocarbons and other compounds with gas chromatographic retention times corresponding to waxes with chain lengths C₃₄−C₄₂. These compounds are short-chain saturated waxes in fruit oils, such as grapeseed and pomace. In seed oils such as sunflower, soybean or peanut, the compounds initially referred to as “soluble esters” are identified as monounsaturated waxes, esters of long-chain saturated fatty acids, and a monounsaturated alcohol, mainly eicosenoic alcohol. Such waxes are absent from corn or rice bran oils.     

Epichlorhydrin in der Wachssynthese

Epichlorohydrine in the Synthesis of Waxes Waxes that are soluble in usual wax solvents are of interest in special fields of application. It is not possible to prepare clear solutions of appreciable concentration using natural waxes, such as carnauba wax or derivatives of montana wax. Although these waxes are well soluble when hot, however, on cooling they separate out as crystalline or pasty masses. For preparing easily soluble waxes a new path of synthesis was found. Thus, waxes having ether or ester groups which were also easily soluble in the cold were prepared by reacting epichlorohydrine with such compounds, which, apart from having a long hydrocarbon chain also possessed a functional group with one active hydrogen atom.     

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

To 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.     

Organogel Formation of Soybean Oil with Waxes

Many waxes including plant waxes and animal waxes were evaluated for the gelation ability toward soybean oil (SBO) and compared with hydrogenated vegetable oils, petroleum waxes and commercial non-edible gelling agents to understand factors affecting the gelation ability of a gelator. Sunflower wax (SW) showed the most promising results and all SW samples from three different suppliers could make a gel with concentrations as low as 0.5 wt%. Candelilla wax and rice bran wax also showed good gelation properties, which, however, varied with different suppliers. Gelation ability of a wax is significantly dependant on its purity and detailed composition. A wax ester with longer alkyl chains has significantly better gelation ability toward SBO than that with shorter alkyl chains indicating that the chain length of a component in a wax such as wax ester is an important factor for gelation ability. The SW–SBO organogel showed increased melting point with increased SW content, showing the melting point range from about 47 to 65 °C with 0.5–10 wt% SW. The effects of cooling rate on crystal size and firmness of a gel were investigated. The dependence of firmness on cooling rate was so significant that the desired texture of an organogel could be achieved by controlling the cooling rate in addition to controlling the amount of gelling agent. This research reveals that a small amount of food grade plant waxes including SW may replace a large amount of the hardstock containing trans-fat or saturated fat.     

Characterisation of waxes by differential scanning calorimetry

The characterisation of hydrocarbon and natural waxes by differential scanning calorimetry is described. It is shown that the determination of the melting, cooling and remelting curves of a wax, and comparison with the corresponding curves of authenticated waxes, affords a rapid and valuable method for the identification of many waxes. Heats of transition of many waxes are also given.     

Einfluß der Gruppenkomponenten auf die Eigenschaften von Estermontanwachsen

Influence of Group Components on the Properties of Montana Ester Waxes The group of wax esters and hydrocarbons was separated from the refined wax R by means of ion exchange on Wofatit SBW and column chromatography on silica gel. A part of the wax acids obtained was esterified with ethyleneglycol. Twenty wax systems having various compositions were prepared from wax acid glycolester and hydrocarbon group components. The wax systems were investigated for drop point, characteristic values, density, electrostatic properties, penetration, flow point, and flow curve. Furthermore, the formation of water emulsions was studied with these wax systems. Relationships between the composition of group components and definite physical and chemical characteristics were established.     

Improved method for the determination of wax esters in vegetable oils

In this work, a modified International Olive Council (IOC) method for wax determination involving a double‐adsorbent layer of silica gel and silver nitrate‐impregnated silica gel is presented (SN method). Column chromatography by the SN method did not show retention of wax esters standards with an even number of carbon atoms (C34–C44), observing recovery percentages higher than 90% even for unsaturated wax esters. All wax fractions were lower by the SN method than by the IOC method, resulting in a percentage decrease in the total wax content (olive oils: 20–50%, crude sunflower oil: 38%, crude soybean oil: 58% and crude grape seed oil: 13%). Olive oils analysed by the SN method showed increases of up to 27% in C40 relative percentage with respect to the IOC method. Additionally, decreases were observed by the SN method in the relative percentages for odd‐carbon atom waxes for the seed oils in comparison to the IOC method (crude sunflower oil: 27%, crude soybean oil: 28% and crude grape seed oil: 13%). The main advantages of the proposed modification consist in its easy implementation and a better determination of wax esters (C34–C60) by controlling their complete recovery and removing interfering substances. The method is suitable for quality control and for authentication of olive oil and seed oils as well as in processing monitoring. Practical applications: The proposed method is useful in the quality, authentication and processing control of fruit and seed oils. Moreover, it can be an important tool for vegetable oil industries to control the efficiency of the wax separation process to prevent turbidity in the refined oil.     

Chromatographic isolation of the original constituents of natural waxes. The composition of ouricuri wax

A chromatographic method was developed which separated a known mixture of alleged wax constituents into four groups,viz., dotriacontane, octadecyl stearate and stearone, octadecanol, and stearic acid on especially prepared alumina. This adsorbent, when prepared fresh, did not give a satisfactory separation of spermaceti wax. On re-use after regeneration by exhaustive washing with methanol and water, spermaceti wax was resolved into esters (95.4%), alcohols (2.6%), and acids (1.2%). A resolution of ourieuri wax into four major classes (nine fractions) was obtained on alumina (M. Woelm, aniontrophie, pII4) of lesser adsorptive activity than the two previous preparations. Two of the latter fractions were further resolved on silica gel. There isa priori evidence that the constitutents of natural plant waxes do not conform rigidly to the pattern of mixtures of simple normal esters. An estimated composition of ouricuri wax (in per cent) is hydrocarbons 1.3, simple esters 23.5, hydroxy-mono-esters 22.4, hydroxy-di-esters 17.2, hydroxy-aeidie-poly-esters 5.4, free acids 8.7, free alcohols 3.0, resins 14.8, moisture 1.4, and ash 0.4.     

Viscoelastic and adhesion properties of EVA/tackifier/wax ternary blend systems as hot-melt adhesives

Two types of wax were added to a ethylene vinyl acetate (EVA) copolymer/aromatic hydrocarbon resin (tackifier) blend in the molten state and the miscibility, viscoelastic and adhesion properties of ternary blends as hot-melt adhesives (HMAs) were investigated. Miscibility and viscoelastic properties were studied using differential scanning calorimetry (DSC), Brookfield viscometry and dynamic mechanical thermal analysis (DMTA), and their adhesion strength was determined in terms of single lap shear strength. DSC thermograms of both types of waxes showed their melting peaks in a similar region to that of EVA/tackfier blend. It was difficult to evaluate the miscibility of ternary blends using DSC because the melting peaks of the waxes overlapped with those of the EVA/tackifier blend, although the glass transition temperature (T _g) of the ternary blend systems slightly increased with increasing wax concentration. However, their storage modulus (E′) increased slightly and loss tangent (tan δ) showed different peaks when two types of wax were added to the EVA/tackifier blend. Therefore, the miscibility of EVA/tackifier blend altered with addition of waxes. In addition, their melt viscosity decreased with increasing wax concentration. Furthermore, the adhesion strength of the ternary blends decreased with increasing wax concentration, despite the increment of storage modulus. These results suggested that the ternary blends of EVA/tackifier/wax were heterogeneous.     

Characterization of Oleogels Based on Waxes and Their Hydrolyzates

In this paper, the structuring of liquid oils, also known as oleogelation, is systematically investigated for the first time using a quasi-quaternary mixing system approach. Native waxes with different quantities of wax esters (WE), n-alkanes (hydrocarbons (HC)), fatty acids (FA), and fatty alcohols (FaOH) are applied in mixtures with hydrolyzed waxes to systematically change the composition. Hydrolyzed waxes contain high levels of FA and FaOH. The model systems are investigated on microscopic level (brightfield light microscopy (BFM), cryogenic scanning electron microscopy (cryo-SEM)) as well as on their macroscopic properties (rheology, gel hardness) and calorimetric behavior (differential scanning calorimetry (DSC)). It is found that sunflower wax (SFW)-based gels (12% structurant) become less hard on any admixture. Beeswax (BW)-based gels show significant increases in hardness when 25% and 50% (w/w) hydrolyzate are admixed. This could be related to stepwise crystallization. Further analysis reveals that the dissolution/melting behavior of the wax ester mixtures can be surprisingly well described as ideal solubility of a single pseudocomponent. The approach to unravel the individual contributions of the different species present in waxes is successful and marks a first step to better understand the systematic of wax functionality as oleogelators. Practical Application: The substitution of hardstock fats in structured oil phases is of interest for two reasons. The improved nutritional profile oleogels offer are beneficial for public health while the elimination of palm oil based ingredients appears to be a general public desire. Among the technical solutions for non-TAG oil structuring waxes are very promising. This is primarily due to their availability, prior consumption, potentially low cost for functionality. Currently waxes are technically and scientifically wrongly treated as single components. In order to better utilize the potential of waxes and design future sourcing strategies it is necessary to understand the wax functionality at a compositional/molecular level. This contribution marks the first step into this direction by considering classes of molecules with respect to their contribution to functionality. This understanding is considered as a key for future compositional design.     

Natural montan wax and its raffinates

Natural waxes have been used by mankind since prehistoric times. Many uses of wax are based on the imitation of its natural functions. Waxes in nature primarily serve to provide protective barriers on the surfaces of living organisms. Their functions are also determined by wax characteristics such as adhesion and cohesion, as well as slip and deformation effects. In ancient times, for example, wax seals were used to help preserve food and beverages. Beeswax has remained an important material for manufacturing candles up to the present day. Recent vegetable waxes have been used in industry since the mid‐nineteenth century, for example in care products. Refined and chemically processed montan‐based waxes are quite similar to naturally occurring vegetable ester waxes in their structure and application characteristics. They are similar in their environmental characteristics and are also nontoxic. Crude montan wax itself belongs to the naturally occurring waxes of vegetable origin such as candelilla wax and carnauba wax.     

Solvent-free slack wax de-oiling—Physical limits

In order to get more knowledge about the fundamentals of solvent-free slack wax de-oiling by melt crystallization, investigations on multicomponent paraffin waxes have been performed, which included X-ray powder diffraction and optical microscopy. The tested neutral oil and medium slack waxes consisted mainly of n- and iso-paraffins with different chain lengths. The results suggest that only n-paraffins formed orthorhombic crystals at room temperature with c-axes corresponding to the average chain length of the paraffin waxes. The crystals were surrounded by less crystalline, rather amorphous, solid phase containing mainly iso-paraffins. The typical solid–solid transition of crystal lattice in neutral oil slack waxes from orthorhombic to hexagonal system at temperatures below melting point increases the mobility of the low melting components. This is the key for the applicability of the melt crystallization process. Investigations on sweating suggest a strong influence of the n-paraffins content on mechanical stability of crystal structures and on the separation efficiency of sweating.     

A Silica Gel Based Method for Extracting Insect Surface Hydrocarbons

Here, we describe a novel method for the extraction of insect cuticular hydrocarbons using silica gel, herein referred to as “silica-rubbing”. This method permits the selective sampling of external hydrocarbons from insect cuticle surfaces for subsequent analysis using gas chromatography–mass spectrometry (GC-MS). The cuticular hydrocarbons are first adsorbed to silica gel particles by rubbing the cuticle of insect specimens with the materials, and then are subsequently eluted using organic solvents. We compared the cuticular hydrocarbon profiles that resulted from extractions using silica-rubbing and solvent-soaking methods in four ant and one bee species: Linepithema humile, Azteca instabilis, Camponotus floridanus, Pogonomyrmex barbatus (Hymenoptera: Formicidae), and Euglossa dilemma (Hymenoptera: Apidae). We also compared the hydrocarbon profiles of Euglossa dilemma obtained via silica-rubbing and solid phase microextraction (SPME). Comparison of hydrocarbon profiles obtained by different extraction methods indicates that silica rubbing selectively extracts the hydrocarbons that are present on the surface of the cuticular wax layer, without extracting hydrocarbons from internal glands and tissues. Due to its surface specificity, efficiency, and low cost, this new method may be useful for studying the biology of insect cuticular hydrocarbons.     

Effect of the extraction and bleaching processes on jojoba (Simmondsia chinensis) wax quality

The aim of the work was to evaluate the effect of extraction method and bleaching on the quality of jojoba waxes from Argentina. Jojoba waxes obtained by cold pressing, Golden wax (expeller‐pressed wax) and Lite wax (bleached wax) were analyzed using standard methods adopted as recommended practices by the American Oil Chemists Society. Physical parameters, fatty acid and alcohol compositions were unchanged among waxes. Cold‐pressed wax was noteworthy by its lower peroxide value, higher amounts of tocopherol and total phenol contents. Accordingly, it presented the best oxidative stability. Bleaching caused a strong decrease in both tocopherol and phenol contents; consequently the bleached wax showed poor oxidative stability.     

橡胶防护蜡的作用机理及影响其防护性能的因素

结合橡胶防护蜡的作用机理说明橡胶制品环境温度、石蜡化学组成、硫化胶交联度、石蜡内部迁移、胶料配合剂和石蜡浓度是直接影响防护蜡性能的因素。指出改性防护蜡是今后橡胶防护蜡的一个发展方向。     

Thermal and mechanical properties of LDPE/sisal fiber composites compatibilized with functionalized paraffin waxes

The effect of maleic anhydride‐grafted hard paraffin wax (MA‐g‐wax) and oxidized hard paraffin wax (OxWax), as possible compatibilizers, on the morphology, thermal and mechanical properties of LDPE/sisal fiber composites were examined. The differential scanning calorimetry (DSC) results show that sisal alone did not change the crystallization behavior of LDPE, while the two waxes influenced the crystallization behavior of LDPE in different ways, whether mixed with LDPE alone or in the presence of sisal. The thermal properties seem to be influenced by the fact that the waxes preferably crystallize around the short sisal fibers, and by the fact that the two waxes have different compatibilities with LDPE. The TGA results show an increase in the thermal stability of the blends in the presence of the two waxes, with LDPE/OxWax showing a more significant improvement. The presence of wax, however, reduced the thermal stability of the LDPE/sisal/wax composites. The presence of OxWax and MA‐g‐wax similarly influenced the tensile properties of the composites. Both waxes similarly improved the modulus of the compatibilized composites, but in both cases the tensile strengths were worse, probably because of a fairly weak interaction between LDPE and the respective waxes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Chemometric Classification of Comb and Cuticular Waxes of the Honeybee Apis Mellifera Carnica

Waxes are important as building material and for the chemical communication of the honeybee Apis mellifera carnica. In this study chemometric tools were established for classifying the different waxes inside the hive. By using gas chromatography in combination with mass spectrometry, components of different types of waxes were analyzed. By considering different substance classes of waxes, discriminant function analyses revealed distinct subtypes of comb waxes and of cuticular waxes. It is shown that the aging of comb wax is in part a spontaneous physicochemical process due to differential volatilities of compound classes with different chain length ranges. On the other hand it is directly influenced by the bees by adding lipolytic enzymes to the comb wax. The data suggest that the varying cuticular wax and comb wax compositions could serve as cues for bees to recognize castes, sexes, or comb age.     

Umweltverhalten und Toxikologie der Wachse

Environmental Behaviour and Toxicology of Waxes Plant and animal waxes are chemically relatively stable nontoxic substances and are used by humans since ages. In the nature waxes have protective function against environmental influences. This protective action is possible due to great resistance of the waxes towards environment, which also means low biological degradability. Obviously, waxes are undigestible and non-toxic in human and animal organism. Partially synthesized waxes based on montana wax, a plant fossil wax, have a structure similar to natural waxes, and therefore they resemble natural waxes with regard to environmental behaviour and are fully harmless from toxicological viewpoint. Also fully synthetic waxes, such as polyethylene waxes and polyethylene oxide waxes have, according to results obtained so far, no undesirable effects on environment. Waxes have been approved in foods worldwide, obviously due to their favorable toxicological properties.     

HYDRODYNAMIC STUDIES IN FISCHER-TROPSCH DERIVED WAXES IN A BUBBLE COLUMN

Gas hold-up and Sauter mean bubble diameter measurements were made in a 0.051 m diameter by 3 m long glass bubble column in the system, nitrogen-molten wax, with three different waxes (paraffin wax FT-300, Sasol's Arge wax and Mobil's reactor wax). Paraffin wax has a tendency to foam and gas hold-up is a strong function of gas distributor type, temperature and start-up procedure, whereas the reactor waxes do not foam and are much less affected by these variables, In experiments at 265°C with a 1.85 mm single hole orifice plate distributor the gas hold-ups were nearly the same for all three waxes. However, significant differences in Sauter mean bubble diameters were obtained in experiments with different waxes; FT-300 wax produced the smallest Sauter mean bubble diameters whereas Mobil's reactor wax produced the largest bubbles. Addition of 1-octadecanol and octadecanoic acid (up to 10wt%) to the FT-300 paraffin wax caused an increase in gas hold-up and a delay in the foam break-up in runs at 265°C with the 1.85 mm orifice plate distributor.     

Separation of some paraffin wax grades using solvent extraction technique

Solvent extraction technique has been used to separate paraffin wax grades; with different characteristics; from El-Ameria light, middle and heavy slack waxes. The wax deoiling has been done by solvent extraction at different extraction temperatures and different solvent feed ratios (S/F by weight). The extraction solvents used are furfural, N-methyl-2-pyrrolidone (NMP) and N, N, dimethylacetamide (DMA). The wax products are evaluated according to TAPPI-ASTM equation and petroleum wax specifications. The data revealed that DMA and NMP are suitable extracting solvents for isolating of semi- and scale-refined grades of paraffin waxes from light and middle slack waxes. But furfural solvent can separate only semi-microcrystalline waxes from heavy slack wax.