Virgin hemp seed oil: An interesting niche product

Virgin hemp seed oil is not widespread on the market, although it is characterised by an interesting fatty acid composition with a high content of polyunsaturated fatty acids. Linoleic acid is the predominant fatty acid, which comes, together with α‐linolenic acid (18:3n‐3), to approximately 80% of the total fatty acids. From a nutritional point of view, up to 7% γ‐linolenic acid (18:3n‐6) and 2.5% stearidonic acid (18:4n‐3) are very interesting. The total amount of tocopherols is high between 80 and 110 mg/100 g, with γ‐tocopherol as the main tocopherol (85%). Due to the high amount of unsaturated fatty acids, hemp seed oil is very susceptible to oxidative deterioration, which results in a fast impairment of the oil during storage. In addition, the high amounts of chlorophyll in the oil due to harvesting of high amounts of immature seeds require light protection, which is often neglected because of merchandising purposes. The virgin oil is characterised by a nutty taste with a slightly bitter aftertaste. The use of virgin hemp seed oil is recommended during mild processing of food without heat.     

Extraction and solubility evaluation of functional seed oil in supercritical carbon dioxide

Hemp (Cannabis sativa L.) seed oil is valued for its nutritional properties and for the health benefits associated with it. Its greatest feature is that the ratio of linoleic acid and linolenic acid is the desirable value of 3:1. In this research, supercritical carbon dioxide was applied to extraction of functional oil from hemp seed. In order to determine the effect of temperature and pressure on the yield of extracted components, the oil was extracted from hemp seed at temperatures between 40 and 80 °C, pressures of 20–40 MPa and a CO₂ flow rate of 3 mL/min. The solubility of hemp seed oil in SCCO₂ determined experimentally was fitted to the Chrastil equation to determine the model parameters. The solubility calculated by Chrastil equation was compared with the experimental data. Finally, the fatty acid profile of the oil was evaluated by gas chromatography-flame ionization detection (GC-FID). There are no significant differences in the compositions of five abundant fatty acid components of the oil obtained at different sampling times with SCCO₂ extraction and other extraction methods.     

Oxidative stability of Echium plantagineum seed oil bodies

Echium plantagineum seed contains a highly polyunsaturated oil (approximately 14% linoleic acid, 10% γ‐linolenic acid, 33% α‐linolenic acid and 14% stearidonic acid); almost half of the fatty acids are omega‐3 fatty acids, so there is an interest in the possible health benefits of this oil, which, once extracted, is prone to oxidation. For the first time in reported literature, oil bodies (OBs), the organelles that store the oil in mature seed, were recovered from E. plantagineum seeds. The oxidative stability of these organelles ex vivo, dispersed in an aqueous continuous phase, was tested against processed E. plantagineum oil emulsions stabilised with either SDS or Tween 20. For both primary and secondary oxidation products the OBs were the most stable form of dispersed oil, and the dispersed systems were all more stable than bulk E. plantagineum oil after incubating at 40°C for 7 days. The possible reasons for the enhanced chemical stability of E. plantagineum OBs are explored in this paper. Practical applications: OBs, the natural store of oil in oilseeds, can be recovered from seeds intact and are relatively stable to oxidation ex vivo. Echium seed OBs, enriched in physiologically active omega‐3 fatty acids, therefore offer an attractive alternative to traditional oil extraction methods and overcome the need to encapsulate the omega‐3 rich oil.     

Storage of sunflower‐seeds: variation on the wax content of the oil

Storage conditions of oil seeds before industrial extraction might influence the quality of the crude oil. The objective of this work was to study the influence of sunflower seed storage conditions (temperature and time) on the quality of the resulting oil in terms of its wax content and composition. Sunflower seeds were stored under different conditions, 10, 21 and 37 °C, in sealed recipients. Extractions of the seeds with hexane were made to obtain the oil at different storage times. The amount of oil extracted (25–40%) showed no significant differences with storage conditions. Wax content of the samples was determined with two different methods (laser polarized turbidimetry and microscopy), and results showed that wax concentration increased with storage conditions (time and temperature). Composition of wax components, determined using capillary gas chromatography, during storage was approximately constant for C₃₅–C₃₉ and showed significant differences for C₄₀–C₄₈ components. Waxes with high carbon number cause more turbidity than waxes with low carbon number, due to their higher melting point, resulting in a low‐quality crude oil and therefore in variations in processing conditions during the oil refining. According to the data showed in this study, seed storage at low temperatures during short periods of time may be the more adequate conditions to obtain high‐quality oil.     

Virgin grape seed oil: Is it really a nutritional highlight?

In comparison to refined grape seed oil which is neutral in taste and smell, the virgin oil is characterized by a pleasant vinous and fruity aroma, which also reminds of raisins if high‐quality raw material is used for the production. Difficulties arise from the susceptibility of the raw material to microbial and enzymatic deterioration as a result of the high moisture content after pressing the juices from the grapes. Grape seed oil has a high content (70%) of linoleic acid, whereas the total part of unsaturated fatty acids amounts to about 90%. In comparison to other edible oils, the oil contains, in addition to tocopherols, antioxidant‐effective tocotrienols. During the oil pressing process, only a small amount of phenolic compounds is transferred into the oil (0.01 mg/g), while most of these nutritionally interesting components remain in the press cake. Here, the content of phenolic compounds is about 2000 times higher. During storage of virgin grape seed oil, the pleasant sensory attributes change, and more and more degradation products like ethyl acetate, acetic acid or ethanol are detectable. Parts of the seed material, which come into the oil during pressing, result in a faster impairment of the oil.     

Utilization of green seed canola oil for biodiesel production

Increasing percentage of green canola seed every year is a serious problem for canola growers. Chlorophyll content of this oil is very high, which makes it more susceptible to photo‐oxidation and ultimately the oxidation stability of the oil is very reduced. Hence green seed canola oil is underutilized for edible purposes. The present work is an attempt to produce high‐quality biodiesel from green seed canola oil and methanol, ethanol and various mixtures of methanol and ethanol using KOH as a catalyst. A mixture of alcohols improved the rate of reaction. After transesterification of green seed canola oil using KOH, the chlorophyll content of the oil was decreased substantially (from 22.1 ppm to 10.3 ppm). Characteristics of the esters prepared from green seed canola oil were well within the limits of ASTM standards. Lubricity of the green seed oil esters was excellent (20% decrease in wear scar area) when added at 1 vol% to the base fuel. Oxidation stability is crucial for long‐term storage of the fuel. Oxidation stability index (OSI) of green seed esters was 4.9 h at 110 °C, which is much less than the European Standard (6 h at 100 °C). The low oxidation stability of green seed esters is attributed to its higher chlorophyll (10.3 ppm) content. An attempt was also made to reduce the chlorophyll content of the oil before transesterification using activated carbon treatment, and it was observed that chlorophyll content was reduced from 22.1 to 2.2 ppm. Copyright © 2006 Society of Chemical Industry     

Composition of organic and conventionally produced sunflower seed oil

The aim of the present study was to highlight the main differences between seed oils produced from conventionally cultivated crops and organically cultivated ones and processed using mild extraction procedures. The composition and the nutritional and health aspects of both types of sunflower seed oils were compared and were analytically tested to determine the macroscopic differences in proximate composition, the main differences in the minor components, the main quality parameters, the in vitro antioxidant activity, and the presence of trans-ethylene steroisomers in FA. No significant trends were found in the oil samples for TAG and FA composition, but remarkable differences were found in the composition of minor components and in the main chemical and analytical quality properties. The organically grown samples had a higher total antioxidant activity compared with the conventional samples. Trans FA were found only in the conventional oils.     

Hemp (Cannabis sativa L.) Varieties: Fatty Acid Profiles and Upgrading of γ‐Linolenic Acid–Containing Hemp Seed Oils

Hemp seeds (HS) constitute a rich nutrient source and contain γ‐linolenic acid (GLA, 18:3, n‐6), which is a healthy fatty acid (FA). The objectives of this research are i) to look for GLA‐rich varieties of unhusked hemp seeds (UHS) and commercial hulled hemp seeds (HHS); ii) to check the influence of different extracting systems on both oil yield and FA profiles; iii) to test a simultaneous oil extraction/GLA‐enrichment process looking to improve GLA content. Hop and European hackberry seeds (both from Cannabaceae family) are also analyzed for comparative purposes. GLA is the most discriminant FA among UHS varieties, ranging in both UHS and HHS seeds from 0.5% to 4.5% of total FA, while hop seeds are the richest GLA source from Cannabaceae (7.2% of total FA). The extraction system selected for hemp seeds processing has a clear influence on oil yields, although, the FA profiles are slightly modified. The use of n‐hexane and n‐hexane:acetone in extractions allows an improvement in oil yields at the same GLA percentage. A process comprising saponification and subsequent cooling allows the improvement of GLA percentage in both hemp and hop seeds extracts at values higher than 10% of total FA, at high yields (>70%). Practical Applications: The global HS market increases significantly year after year and the demand of hemp products is increasing rapidly. The natural GLA sources in nature are limited, and although hemp contains GLA, this reaches low percentages in the oil. Hemp is a well‐established crop with highly standardized agricultural technologies, thus, the development of any well‐designed processes feasible for application in oil extraction industries, would allow the development of new GLA‐based functional seed oils. This would boost the development of the agricultural and food industries dedicated to revaluing hemp products.     

Structure and properties of hemp fabric treated with chitosan and dyed with mixed epoxy‐modified silicone oil

To enhance the color yield and improve the soft handle, hemp fabrics were treated with chitosan of molecular weight 4200 and degree of deacetylation 0.90, and then dyed using Remazol Brillant Blue R with mixed epoxy‐modified silicone oil in different volume ratios. The structural changes in hemp fibers were investigated by means of scanning electron microscope, FTIR, TG, DSC, and XRD. The properties of tensile, bending, dyeing, and color fastness for hemp fabric were also studied. The results showed that when compared with the untreated hemp fiber, the thermal performance of chitosan/silicone oil‐modified hemp fiber changed and the percent residual weight increased in the range of temperature 25–550°C. The crystal grain size decreased and the degree of crystallization increased. For chitosan/silicone oil‐treated hemp fabric, the flexural stiffness and tensile properties degraded. The maximum color yield (K/S value) was obtained when the volume ratio of dyeing liquor to silicone oil was 2 : 1. The color fastnesses to rubbing and wet scrubbing were also improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Management of environmental crop conditions to produce useful sunflower oil components

The objective of this study was to investigate the impact of water availability and temperature after flowering on oil, major fatty acid and sterol contents in seeds of standard and oleic sunflower genotypes, under managed and controlled field conditions. When water deficit was effective from the beginning to the end of anthesis, it modified the fatty acid composition of standard hybrids. When water was supplied, a major enhancement of oleic acid content was associated with a concomitant reduction of linoleic acid content and a decrease in saturated fatty acid contents. Higher temperatures increased the oleic acid content in seeds of standard hybrids. Oil content was enhanced under colder temperature and irrigation. The content of minor oil components, phytosterols, was also enhanced when seed development occurred under high temperature and severe water stress. As a whole, the data showed that combining water management, sowing date and choice of genotype may orientate the biosynthesis of seed components and thus generate seed composition variability suitable for industrial purposes.     

Virgin sunflower oil

Sunflower oil is the second most important virgin oil in Europe but, from the nutritional point of view, the assessment of this oil has become increasingly poorer over the last few years because of the high amount of linoleic acid in traditional sunflower seeds. Today sunflower oil with a high oleic acid content is coming more into the focus of interest since the fatty acid composition is more comparable to rapeseed and olive oil. Another important aspect is that the high content of oleic acid results in a high oxidative stability, making this oil interesting for a wide range of applications. A special challenge is the production of high‐quality tasty virgin sunflower oil because, in contrast to other raw materials, about 30% of sunflower seeds consist of hulls that are covered by waxes. During oil processing these waxes are co‐extracted with the oil, resulting in undesired turbidity of the oil on storage. Pressing of the raw material is done in a screw press or expeller and results in residue fat contents between 7 and 15% depending on the pressing conditions. We discuss two possibilities to avoid or to remove waxes by dehulling of the seeds or winterisation of the resulting oil. Dehulling is carried out by an impact dehuller with removal of the hulls by airflow and gravity. Removal of hulls before pressing improves the sensory quality of the oil because it results in products with a mild sunflower seed‐like nutty taste, while oils from whole seeds often have a woody and bitter taste. In addition, the development of heat during pressing is reduced if dehulled seeds are used for oil production. Conventional sunflower seeds are processed mainly in big oil mills, whereas in small and medium‐sized facilities organic raw material is in use.     

Quality differences between pre‐pressed and solvent extracted rapeseed oil

Most seed oils are obtained by pre‐pressing the crushed seeds followed by solvent extraction of oil from the press cake. The prepressed oil will contain no solvent residues, and is moreover expected to contain more nutritionally valuable compounds, which can in turn enhance the oxidative stability of the oil. However, reports on differences between extracted and pressed oils are scarce. Therefore, in this study, for a case study on rapeseed oil, the composition and quality were systematically compared between pre‐pressed and solvent extracted oil. In the extracted oil, solvent residues and a clear sensory difference were detected, which disappeared almost completely during refining. The crude oils had a high content in free fatty acids and in primary and secondary oxidation products, which were higher in the extracted than in the pressed oil. However, surprisingly, also the content of minor compounds was slightly higher in the extracted oil than in the pressed oil. This can be explained by a selective extraction of those compounds into the solvent. During refining, a difference between pressed and extracted oils still existed but was less pronounced. The slight difference in antioxidants content might explain the higher oxidative stability of extracted over pressed oils. Practical applications : Traditionally, high yields of vegetable oils are obtained by pre‐pressing the seeds, followed by solvent extraction of the residual oil from the press cake. The solvent extraction leads to higher oil yields, but is expected to affect the composition and quality of the oil, and has moreover negative environmental impacts. In this study, the solvent extracted oil contained slightly higher levels of tocopherols and phytosterols, and had slightly higher oxidative stability, which are desirable quality aspects. In contrast, the solvent extracted oil contained also higher levels of undesirable phospholipids, as well as solvent residues, which were, however, removed during degumming and deodorization, respectively. These results suggest that the final quality of refined pre‐pressed and solvent extracted oils is comparable from nutritional and safety point of view. A choice for pressing instead of solvent extraction will, therefore, rather be driven by sustainability concerns than by nutritional aspects.     

Why is it so difficult to produce high‐quality virgin rapeseed oil for human consumption?

Virgin rapeseed oil becomes increasingly popular for the consumer because of the pleasant seed‐like and nutty taste and smell. The oils are produced in small and medium‐sized facilities by extraction of rapeseed using only a screw press and purifying the oil by sedimentation or filtration. Thus, the producers have no chance to improve the oil quality if the seed quality is bad. Therefore, it is an art to produce high‐quality virgin rapeseed oil that is accepted by the consumer. The most important step in the production chain of virgin rapeseed oil is the period after harvest until the processing, while extraction of the oilseed and purification has only a minor influence on the oil quality. The paper describes the pitfalls during the production of virgin rapeseed oil which primarily wait for the producer during storage of the seeds. Improper storage conditions result in increased metabolic processes in the seeds and an increase of the populations of microorganisms and insects, which finally leads to the degradation of nutrients and the formation of unpleasant aroma compounds.     

Current advances in sunflower oil and its applications

The fatty acid and triacylglycerol composition of a vegetable oil determine its physical, chemical and nutritional properties. The applications of a specific oil depend mainly on its fatty acid composition and the way in which fatty acids are arranged in the glycerol backbone. Minor components, e. g. tocopherols, also modify oil properties such as thermo‐oxidative resistance. Sunflower seed commodity oils predominantly contain linoleic and oleic fatty acids with lower content of palmitic and stearic acids. High‐oleic sunflower oil, which can be considered as a commodity oil, has oleic acid up to around 90%. Additionally, new sunflower varieties with different fatty acids and tocopherols compositions have been selected. Due to these modifications sunflower oils possess new properties and are better adapted for direct home consumption, for the food industry, and for non‐food applications such as biolubricants and biodiesel production.     

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil via response surface methodology

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil (HOSO) via response surface methodology is presented in this study. The results of an experimental program conducted on an industrial‐scale deodorizer were analyzed statistically. Predictive models were derived for each of the oil quality indicators (QI) in dependence on the studied variable deodorization process parameters. The deodorization behavior of some minor components was analyzed on a pilot‐scale deodorizer. For comparison, a similar experimental program was also performed on the laboratory‐scale. The results of this study demonstrate that optimization of the deodorization process requires a suitable compromise between often mutually opposing demands dictated by different oil QI. The production of HOSO with top‐quality organoleptic and nutritional values (high tocopherol and phytosterol contents and low free and trans fatty acid contents) and high oxidative stability demands deodorization temperatures in the range between 220 and 235 °C and a total sparge steam above 2.0% (wt/wt in oil). The response surface methodology provides the tools needed to identify the optimum deodorization process conditions. However, the laboratory‐scale experiments, while showing similar response characteristics of QI in dependence on the process parameters and thus helpful as a guide, are of limited value in the optimization of an industrial‐scale operation.     

Production technology and characteristics of Styrian pumpkin seed oil

Cucurbita pepo subsp. pepo var. Styriaca, the so‐called Styrian oil pumpkin, is a phylogenetically young member of the Cucurbita spp. A single mutation occurred only in the 19^th century and led to dark green seeds with stunted outer hulls. This mutation facilitated the production of Styrian pumpkin seed oil that became a regional specialty oil in the south‐eastern part of Europe during the last few decades. We describe in this article the production and economic value of this edible specialty oil as well as the most important parameters relevant for its quality. Furthermore, we report on its molecular composition including fatty acids, vitamins, phytosterols, minerals, polyphenols, and those compounds that are responsible for its color, taste and flavor. Finally, information is provided on potential contaminants of Styrian pumpkin seed oil as well as its putative beneficial health effects.     

Development and commercialization of GLA safflower oil

GLA safflower oil is a new commercial source of gamma‐linolenic acid (GLA), an important dietary omega‐6 fatty acid with properties similar and complementary to those of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In its native form, GLA safflower oil contains 60–70+% GLA. It is one of the first dietary supplements developed using modern biotechnology methods and is the first of a new generation of genetically modified (GM) plant oil ingredients developed solely for improvement of human health and nutrition.     

Tocopherol oil concentration in field-grown sunflower is accounted for by oil weight per seed

Tocopherols are natural antioxidants that increase the stability of fat-containing foods and perform important biological activities. Significant variations (389 to 1873 μg g oil⁻¹) in the total tocopherol concentration of sunflower seed oil have been reported. The main objectives of this work were to determine the influence of intercepted photosynthetically active radiation on tocopherol concentration during seed filling and to establish and validate relationships between tocopherol concentration in oil and other quality variables of the seed. Seven sunflower hybrids were grown under good water and nutritional conditions in two similar experiments carried out in two contrasting environments. Treatments were applied to modify the amount of radiation intercepted per plant during seed filling in order to obtain a range in oil yield per plant and its components. Greater per plant intercepted radiation decreased the tocopherol concentration in oil. Tocopherol concentration decreased when oil weight per seed increased. Tocopherol concentration stabilized for oil weight per seed higher than 23 mg oil seed⁻¹. This exponential relationship accounted for 73% of the variability in tocopherol concentration (507 to 1203 μg g oil⁻¹) despite differences in hull type, locations, hybrids, and radiation treatments. The proposed relationship acceptably predicted independent results. Crop management techniques could lead to seeds with greater concentrations of tocopherols.     

Physicochemical studies of hemp (Cannabis sativa) seed oil using enzyme‐assisted cold‐pressing

The effects of enzyme‐assisted cold‐pressing (EACP) on the physicochemical attributes of Cannabis sativa (hemp) seed oil were investigated using five enzyme preparations: Protex 7L, Viscozyme L, Kemzyme, Feedzyme, and Natuzyme. The oil contents (28.4–32.8%) offered by the enzyme‐treated hempseeds were found to be significantly (p <0.05) higher than that determined for the control (26.7%). The protein, fiber, and ash contents of the seeds were unaffected by the enzyme treatment. There were no significant (p >0.05) variations observed for the values of iodine number, refractive index, density, unsaponifiable matter and fatty acid composition between the enzyme‐extracted and control hempseed oils. The levels of saponification value, free fatty acids, iodine value and peroxide value were slightly varied between the oils tested. The color intensity of the enzyme‐extracted oils was also higher than that of the control oil. A relatively higher level of tocopherols (724.4–788.8 mg/kg) was observed in the enzyme‐extracted oils compared to the control (691.2 mg/kg), showing an enhancement of ca. 4.8–14.1% in the total tocopherols. The Rancimat profiles and sensory scores of the enzyme‐extracted oils were noted to be improved compared to the control. The results of the present analysis (with respect to the control) showed that the enzyme added during the hempseed cold‐pressing resulted in considerably higher oil yields, without adversely affecting the quality of the oil.     

Physical‐chemical characteristics and oxidative stability of oil obtained from lyophilized raspberry seed

Fresh raspberry (Rubus idaeus), cultivar Willamette, was freeze‐dried (lyophilization). A byproduct of lyophilization is “fine dust” of raspberry consisting of finely ground raspberry fruit body and seed. The seeds were separated. The seed oil was isolated and its physical and chemical characteristics were determined. Parameters that characterize the seed and quality of the oil were examined, including fatty acid composition, oxidative stability under different storage conditions, and radical‐scavenging activity. The fatty acid composition was determined by GC/FID and the contents of the dominant fatty acids were found as: oleic 16.92%, linoleic 54.95%, and α‐linolenic acid 23.97%. The oxidative stability of the oil was poor. The induction period by Rancimat test at 100 °C was 5.2 h. The radical‐scavenging activity is similar to that of resveratrol [1,3‐benzenediol 5‐(1^E‐2‐4‐hydroxy‐phenyl‐ethyl)]. Although this product is used in the candy industry, it would be far more useful if raspberry oil of satisfactory quality could be extracted. This paper demonstrates that sifted lyophilized seeds can be used for the extraction of oils. This process allows for maximal usage of the byproducts, reduces losses and it increases the development of new products.