Camelina [
Camelina sativa (L.) Crtz.] is an important oilseed crop with several excellent qualities that are contributing tothe rising interest in its use for food, feedstock, pharmaceuticals, biofuel and other industries
(Betancor et al., 2015; Haslam et al., 2016), its history goesback to the Bronze Age
(Putnam et al., 1993). Although camelina has been cultivatedin Europe for over 2000 years for oil and livestock fodder, the crop has gained increased popularity recently as abiofuel source due to its oil content. Although widely grown up to the early 1940’s commercial production ceased with the introduction of oilseed rape
(Putnam et al., 1993). In addition,
Quezal and Santa (1962) indicate the presence of
Camelina microcarpa in the high Plateaus of Algeria as wild plant. The lower cost of hydrogenating rape oil and the lack of knowledge on the value of oils containing a high percentage of polyunsaturated fatty acids were the main causes of the lack of interest in camelina. There are two cultivated forms such as winter and summer, but the winter forms yielding higher than summer
(Mosio-Mosiewski et al., 2015). In addition, the camelina crop canbe grown on marginal farmland, with relatively low inputs and no irrigation. This plant also has very high resistance against pests such as cockroaches and pollen eating that is common in oil seeds. Underfavorable conditions, camelina crops yield >2 t/ha, but lower yields (1.2 to 2.2 t/ha) are observed under conditions of limiting nutrients or water (
Crowley and Frohlich, 1998;
Gehringer et al., 2006). The particular value of camelina oil is given by its content in polyunsaturated fatty acids (50-60%), by its content in omega 3 (35-40%) and by its content in omega 6 (15-20%). Due to these properties, camelina oil is one of the richest vegetal sources of omega 3. Extraction of oil from camelina seeds by mechanical expeller yields a meal that consists of approximately 10% residual oil, 45% crude protein, 13% fibers, 5% minerals and other minor constituents such as glucosinolates and vitamins, which in turn has prompted studies for its use as an aquaculture and animal feed supplement. Present review covers various aspects of
Camelina sativa research including its origin,classification and genetics, morphology, minimum inputs to grow camelina, allelopathic potential and camelina products and applications.
Origin of Camelina
Camelina sativa is an ancient crop that is believed to have evolved as a weed in fields planted with flaxseed
(Chaturvedi et al., 2019); it is originated from Southern Europe and South-West of Asia
(Berti et al., 2016), although the exact region remains uncertain. In adition, a molecular analysis of a number of
Camlina sativa accessions of Russian- Ukrainian origin revealed that this region is a hotspot for genetic diversity in
Camlina sativa, suggesting that it could be the centre of origin for this species
(Ghamkhar et al., 2010). Known as “gold-of pleasure” or “false flax”, after losing any prominence in Europe during the 1940s, camelina breeding research started again in Germany in the 1980s
(Vollmann et al., 2005).
Classification and genetics
Camelina [
Camelina sativa (L.) Crantz] is a summer or winter growing annual herb in the family Brassicaceae, Class of Dicotyledons and is related to
Arabidopsis thaliana, a much researched species. As illustrated in the Fig 1,
C. sativa (2n=40), is an ancient oilseed crop with a new found application as an aviation biofuel and omega-3 rich feedstock. The genus Camelina, represented by seven or eight species
(Brock et al., 2019), belongs to one of the most karyo logically variable crucifer genera, with chromosome numbers ranging from 2n = 12 to 40 (2n = 12, 14, 16, 26, 28, 32, 36, 38 and 40) and a threefold genome size variation
(Hutcheon et al., 2010; Brock et al., 2018).
Morphological description
Morphologically, camelina has a smooth or hairy steam, whose height may be between 65 and 110 cm (Fig 2A)
(Berti et al., 2016). Rosette leaves are not lobed and are withered at flowering, leaves on stems are alternate, lanceshaped, lacking a petiole and usually clasping, they are typically 2 to 8 cm long and 2 to 10 mm wide and may be smooth or have a few, primarily forked, hairs (
Francis and Warwick 2009). The inflorescence is composed of small pale-yellow flowers (Fig 2B), which are made up offour petals that further develop pear-shaped silicles (Fig 2C). The final number of pods per plant can range from approximately 60 to 115 and it is positively and negatively correlated with increased N fertilization and increased sowing density, respectively
(Czarnik et al., 2018). Camelina seed pods are siliques; globular and rounded, divided by a septum and typically contain 10 to 25 seeds; at maturity, seed pod change their color from green to yellow-reddish and then completely dry at full maturity
(Jankowski et al., 2019). Camelina seeds are brown to light brown with a thousand kernel weight (TKW) of 1 to 2 g (
Meakin, 2007).
Minimum inputs to grow camelina
Camelina is an annual crop which can be cultivated both in spring and in winter seasons
(Dobre et al., 2014; Berti et al., 2016), winter varieties showing a high resistance to harsh climate conditions. In addition, camelina has modest requirements for agro-ecological conditions; an important feature of camelina is its high level of resistance against insect pests and plant pathogens and low doses of nutrients
(Volmann et al., 2005). Kim et al., (2015) proved that the Camelina cultivation requires low water and fertilizers compared with other crops from the same family. Moreover, it was noted the adaptability of Camelina to different medium conditions
(Berti et al., 2016) and its capacity to grow in marginal lands
(Kim et al., 2015, Petre et al., 2015). Camelina is well adapted to cool temperate semi-arid climates (
Mulligan, 2002) and it is more tolerant of drought and spring freezing in comparison with other crops from the same family
(Krzysztof et al., 2019). Due to the small seed size (Fig 3), camelina is planted at shallow depths (6-8 mm) to ensure plante mergence and good stand establishment.In addition, seeding rate of 5-7 kg seeds ha-1 is adequate to ensure good dense stand. Camelina can be grown under conventional tillage or no-till conditions (
Enjalbert and Johnson, 2011). However, excessive crop residue can reduce seedling emergence with no-till,therefore seeding rates need to be increased under no-till (
Enjalbert and Johnson, 2011).
Allelopathic -
Camelina sativa
Allelopathy is expected to be an important part of integrated weed management as a supplementary tool for weed control in the agro-ecosystems because of increasing public concern about harmful effects of pesticides on the environment and human health as well as increasing rate of weed resistant to known chemicals
(Uremis et al., 2009). Selective breeding has been done to improve the allelopathic activity in some crops: rice, wheat and barley (
Bertholdsson, 2007;
Kong et al., 2011). Brassicaceae family plants are frequently cited as allelopathic (
Jafariehyazdi and Javidfar, 2011) and include oilseed [canola (
Brassica napus L
.), camelina [
Camelina sativa (L.) Crantz.], mustard (
Brassica rapa L.)] and vegetable crops [broccoli (
Brassica oleracea L.) and radish (
Raphanus sativus L.)]. In addition, Brassica species contain allelochemical compounds as glucosinolate and their corresponding degradation products that are, under special conditions, released to environment and affects seed germination and plant growth (
Bones and Rossiter, 1996). Leaves are the main source of allelopathic inhibitors and the focus of many allelopathic investigations;
Lovett and Duffield (1981) reported positive effects of
Camelina sativa leaf washings on flax growth, which observed no significant increase in flax root or shoot weight in response to Camelina leaf washings.
Camelina sativa in rotation cropping systems
Leclère et al., (2018), reports that the
Camelina sativa was identified as a possible summer cover crop in double cropping systems, this type of approach tremendously widens the opportunities of Camelina to pass from the status of niche crop to cash cover crop in Europe. One new potential use of Camelina is as a cover crop in maize soybean rotations in the Midwest USA; winter Camelina can be direct sown following the harvest of short-season cereals such as wheat (
Triticum aestivum L.)
(Berti et al., 2015) and ithas the potential to be established by broadcasting into longer season standing crops such as maize and soybean. On the contrary, Previous cropping systems research reported growing Camelina in place of fallow in a wheat-fallow rotation showed minimal reduction in winter wheat yield (6%) in wet years
(Hess et al., 2011). However, in drier years, winter wheat yields following Camelina were 13%-30% lower than yields after fallow
(Chen et al., 2015; Hess et al., 2011).
Camelina products and applications
The high oil content of Camelina seeds could also favor the accumulation of bioactive compounds such as terpenes, whichare components of essential oils used in food additives, cosmetics, drugs, rubber and lubricants
(Degenhardt et al., 2009). Camelina oil can be used for biodiesel and renewable jetfuel production
(Mupondwa et al., 2016). In addition, Camelina oil and meal have other industrial applications such as making adhesives, coatings,gums, resins and varnishes
(Kim et al., 2015; Nosal et al., 2015).
Camelina oil extraction methods
Camelina oil is extracted from the seeds by many processes such as cold pressing, solvent extraction or super critical CO
2 extraction. The cold pressing technique is applied in two ways: screw press and/or hydraulic press. It is an alternative technique to conventional solvent extraction method because it does not require the use of organic solvent or heat. This technique isaffected by temperature, frequency and press nozzles size
(Popa et al., 2017). Supercritical CO
2 (SC-CO
2) fluid extraction is an alternative technique to cold pressing.
Belayneh et al., (2015) compared the composition of oil obtained using 3 different extraction methods: classical extractions by Soxhlet and cold pressing and supercritical-CO
2 extraction. The extraction yields obtained were: 35.9% -Soxhlet extraction with hexane during 6 hours, 29.9% -cold pressing extraction, respectively 31.6% - supercritical-CO
2. The last mentioned method showed a high efficiency regarding oil recovery-88% of the quantity recovered normally with hexane extraction. There were no significant differences between the compositions of the three oils
(Belayneh et al., 2015).
Camelina seed composition
Camelina sativa oil
Camelina sativa oil is the main product from CS seeds and the average yield of oil from the seeds isabout 40% on dry matterbasis (
Zubr, 2009). Camelina seeds contain over 38.9% fat, 30 per cent a-linolenic acid (18:3 n-3) (an omega-3 fatty acid) and 25.8 per cent crude protein. Due to the high oil content, omega-3 fatty acid and crude protein, finding alternative use of Camelina meal (a co-product obtained from Camelina seed after oil extraction) in animal diets will increase the market value ofthe crop. The high levels of a-linolenic acid (C18:3, ALA) in camelina oil provide an ideal plant chassis for the synthesis of omega-3 long chain polyunsaturated fatty acids (LC-PUFAs) like eicosapentaenoic acid (C20:5, EPA) or docosahexaenoic acid (C22:6, DHA). Omega-3 LC-PUFAs are central dietary recommendations for fetal development and adult cardiovascular and cognitive health.
Also almost the same percentages of linolenic, linoleic, oleic, eicosenoic and erucic acids were reported following studies conducted by different researchers, as it is shown in Table 1. The oil is also very rich in natural antioxidants, such as tocopherols, making this highly stable oil very resistant to oxidation and rancidity. Camelina oil has a high content of eicosenoic acid, which is rarely found in plants; this makes Camelina a source of medium chain fatty acid (MCFA), which obtained only from palm and coconut oils
(Righini et al., 2016). MCFA are known for their positive action on metabolic disorders of lipids, by suppressing the fat depositions and oxidation in animals and humans (
Nagao and Yanagita, 2010).
Camelina sativa meal
Camelina sativa meal is the product obtained from high-pressure crushing of seed or from a pre-presssolvent extraction process, which removes the oil from the whole seed; it represents an important output with considerable economic value. Camelina meal is used in animal feed
(Nain et al., 2015); chicken
(Ciurescu et al., 2016) and sheep
(Cieslak et al., 2013) fed Camelina meal had lower blood plasma cholesterol and higher contents of a-linolenic, eicosapentaenoic acid and docosahexaenoic acid in muscles. Cold-pressed Camelina meal contains 35-40 per cent crude protein, 6-12 per cent fat, 6-7 per cent ash and 41 per cent neutral-detergent fiber. The gross energy is 4600-4800 kcal/kg
(Cherian et al., 2009). In addition,
Camelina sativa meal is a good source of vitamins B1 (thiamin), B3 (niacin) and B5 (pantothenic acid).Thiamin play functions as a coenzyme intransketolation and is important in neural transmission. It is directly involved in maintenance of normal appetite and healthy attitude (Berdanier, 2002).
Zubr (2010) reports that
Camelina sativa meal is a marginal source of mineral except the micromineralsiron, manganese and zinc. Analyses of
Camelina sativa reveal prevalently low content of macro-minerals. The highest content between 1.0-1.6% is calcium, potassium, phosphorus. (
Zubr, 2010). Among micro-minerals,
Camelina sativa presents markedly high content ofiron (329 μg/g), manganese (40 μg/g) and zinc (69 μg/g) (
Zubr, 2010).
Applications of Camelina sativa
In total, 80% of
Camelina sativa oil is utilized in health-food products. Approximately, 14% of oil is used in industrial raw materials like cosmetics, detergents, surfactants, emulsifiers, lubricants, fuel, oleo chemicals, plasticizers and adhesives (
Carlsson, 2009). In addition, the camelina by-products, such as
Camelina sativa meal are valorized especially for animal feed
(Woyengo et al., 2016).
Feed stock and biofuels
Biodiesel defined as a fuel comprised of mono-alkyl esters of long chain fatty acids derived from a renewable lipid feedstock, such as, animal fats or vegetable oils (
Litvin, 2009), provide a clean and effective fuel for diesel engines. Thus biodiesel is distinguished than diesel fuel in terms of aromatic content, Sulfur content, flash point and biodegradability. Recently, as feedstock for biofuel production,
Camelina sativa has attracted renewed interest due to some useful and distinguishable agronomic traits such as: very short growth cycle, resistance to drought andlow temperature, capacity to growth in marginal soils and lower demand of fertilizers, herbicides and pesticides
(Vollmann et al., 2007). In addition,
Camelina sativa oil is mainly used for the jet fuel production. The jet fuel obtained from
Camelina sativa oil tested versus the classical one proved no degradation of the engines and its use resulted in lower soot and carbon monoxide emissions
(Berti et al., 2016). For biofuel production, it was tested also the use of
Camelina sativa meal, which by pyrolysis may lead to high energy liquid fuels with increased stability due to low oxygen content (
Goímez-Monedero et al., 2015). The
Camelina sativa base feed is given to different terrestrial animals, aquatic animals and birds to improve their general health;
Hixson and Parrish (2014) have tested the replacement of fish oil and fish meal used in aquaculture Atlantic cod diet with
Camelina sativa oil and meal.
Camelina sativa meal is full of mineral content that makes it suitable for animal feed (Table 2). According to experimental data, the use of fish oil can be replaced with Camelina oil in Atlantic salmon diet, without any impact on weight gain
(Hixson et al., 2014). Hence, it is clear that
Camelina sativa products as diet are suitable because has good amount of micronutrient
(Bullerwell et al., 2016). In addition,
Camelina sativa meal can be used as additive for animal feed because it has good amount of protein and omega-3-FA (
Ryhänen et al., 2007). (Table 2). It is also rich in protein and poly unsaturated fatty acids (PUFAs) and can be used in cattle feed (
Hurtaud and Peyraud, 2007).
Camelina sp meal has high amount of protein and energy, which can be a good source for ruminant feeds (
Matthäus and Zubr, 2000). In dairy cows, this meal can reduce milk fat, resulting in more spreadable butter (
Hurtaud and Peyraud 2007).
Human nutrition
Many studies in human nutrition and health have determined the relationship between the diet and the occurrence of various diseases. The using
Camelina sativa as animal feed encouraged researchers to use them as human feed. Due to high content of unsaturated fatty acids in
Camelina sativa oil its oxidative stability should be an important factor,
Camelina sativa oil was found to be more stable towards oxidation than highly unsaturated linseed oil but less stable than rapeseed, olive, corn, sesame and sunflower oils (
Abramovič and Abram, 2005). In addition, the
Camelina sativa oil is a rich source of essential fatty acids (linoleic and a-linolenic acids) as well as omega-3 (α-linolenic)
(Hrastar et al., 2009). The low content of erucic acid represents an advantage when using
Camelina sativa oil in human diet, considering that the ingestion of high quantities of erucic acid are thought to be responsible of cardiac lipidosis (
Vollmann and Eynck, 2015). The high levels of omega-3 lipids in
Camelina sativa oil are perceived as beneficial for human health (
Zubr, 1997;
Eidhin et al., 2003) and the high levels of tocopherols, including vitamin E, make
Camelina sativa oil more stable to oxidation than other high omega-3 oils such as linseed oil
(Hrastar et al., 2009).
Camelina is known to have the capacity to reduce serum triglycerides and cholesterol; also, due to its fatty acids profile the camelina oil may be used in human diet as nutraceutical: in salads, for cooking, in margarine with enriched content of omega-3 fatty acids, in salad dressings, mayonnaise, ice cream (
Abramovič and Abram, 2005).
Medicinal therapeutic applications
Human body cannot synthesize α-linolenic acid (omega-3) and its deficiency may result in clinical symptoms including neurological abnormalities and poor growth. Therefore, a-linolenic acid should be included in the diet. The consumption of
Camelina sativa oil riched on α -linolenic acid (32.8-33.0%) can help to improve the general health to the desired level (
Lu and Kang, 2008). In addition, the meal (Cake) of Camelina seed contains many phenolic compounds, which showed antioxidant activity like tocopherols, sinapine and sinapic acid
(Salminen et al., 2006). Many studies proved the efficiency of using the Camelina oil in treatment of burns, wounds and eye in flammations and it is applied topically; in Slovenia, Camelina oil is used as traditional home remedy
(Chaturvedi et al., 2019). Dobrzyńska and Przysławski (2021) determined cholesterol reducing effect of Camelina oil in a test with mildly and moderately hypercholesterolemic subjects. The volunteers consumed 33 mL Camelina oil per day during 6 weeks. Their total cholesterol in blood serum was reduced from 5.9 to 5.6 m mol/L and LDL (low density lipoprotein) decreased by 12.2 per cent. Experimental evidence, however, proves that Camelina oil possesses a cholesterol reducing property. Besides the effects of a-linolenic acid and tocopherols also phytosterols were found effective in lowering cholesterol
(Ortega et al., 2006). In traditional home treatments,
Camelina sativa oil is useful in the treatment of stomach and duodenal ulcers (
Rode, 2002).
Camelina oil in cosmetics
A number of other industrial uses for camelina oil have been proposed, including use in paints, inks, soaps, varnishes, lubricants, cosmetics and as a plastic additive (
McVay and Lamb, 2007;
El Bassam, 2010). The specific dermatological effects of poly-unsaturated fatty acids make
Camelina sativa oil suitable for cosmetic applications, such as cosmetic oils, skin creams and lotions (
Hurtaud and Peyraud, 2007). Camelina oil also has a total tocopherol content of 750 mg/kg oil
(Abramovic et al., 2007) and phytosterols (511 mg/100 g oil)
(Schwartz et al., 2008) which make it a suitable ingredient in cosmetic preparations that help inpreventing photo-oxidation.
Pesticide and antifungal activities of Camelina sativa
Camelina sativa has vast number of neutraceutically important bioactive compounds.Bioactive components like different classes of phenolics, glucosinolates, tocopherols, poly unsaturated fatty acids, mono unsaturated fatty acids, polysaccharides and lignans are reported by researchers in
Camelina sativa (
Abramovic and Abram, 2005;
Berhow et al., 2013), it’s can be used as potent antifungal, pesticidal, or insecticide in the field crops. The study of
Hu et al., (2011) proved that the applied of
Camelina sativa meal at 5% and 1% to soil, it suppresses the
Phymatotrichopsis omnivore sclerotial germination and hyphal growth of fungi, this fungus can infect the roots of over 2000 different species of plants and often results in rapid plant wilting and death; by using
Camelina sativa meal one can protect fungal attack
(Hu et al., 2011). In addition, Glucosinolates (GSLs) are secondary metabolites and act as natural pesticides and prevent herbivory (
Halkier and Gershenzon, 2006). GSLs in the presence of waterafter an unstable intermediate formation converts into thiocynate, isothiocyanate, ornitrile, these compounds help in defense of plant (
Spencer and Daxenbichler, 1980).
Glucosinolates
Glucosinolates (GSLs) are one group of compounds found within and on the surface of cruciferous plants that can act as deterrents or attractants of insect pests and that have been shown to play a part in the recognition of host plants by insects. Glucosinolates are natural, sulfur-rich anionic secondary metabolites, widely distributed in plants of the order Brassicales, GSLs are natural pesticides
(Fahey et al., 2003; Halkier and Gershenzon, 2006). Camelina seed contains two aliphatic glucosinolates in a significant level; these are glucoarabin (GSL9) and glucocamelinin (GSL10) while the third glucosinolate (GSL11) is in very small amount (
Vaughn and Berhow, 2005). The research of
Sizmaz et al., (2016) proved that the Camelina meal had greater level of glucosinolates than Camelina seed.
Toxicity effects of glucosinolates
GSLs themselves are biologically inactive molecules, but GSL degradation products are biologically active and known for their diversified biological effects. In addition, the hydrolysis catalyzed by thioglucosidases leads to the formation of biologically active products. The toxicity of GSLsis generally attributed to the isothiocyanates, thiocyanates, oxazolidinetiones and nitrilesoriginating from enzymatic cleavage of GSLs by myrosinase.
Obour et al., (2015) showed that the Camelina has two anti-nutritional factors, the presence of high erucic acid and glucosinolates which limits the amount of meal that can be fed makes higher dietary consumptions of Camelina oil unsafe. The concentration of glucosinolates in dry Camelina seeds ranges from 13 to 36 mol/g. When ingested in sufficient quantity, Glucosinolates cause deleterious effects in animals such as reduced palatability as well as decreased growth and production. Consequently, Camelina meal cannot exceed 10 wt % of the total foodration given to feedlot beef cattle and broiler chickens in the United States. However, even a 10% ceiling represents significant market potential where large numbers of animals are raised for human consumption, thus representing an important revenue stream for Camelina meal (
Moser, 2010).
Beneficial effects of glucosinolates
The contact of GSs with the enzyme myrosinase in the presence of water causes immediately the hydrolysis. The hydrolysis products consist of an aglycone moiety, glucose and sulphate. The aglycone moiety is unstable and re-arranges to form isothiocyanates (ITCs), thiocyanates, nitriles, oxazolidinethiones and epithionitriles depending upon the structure of the GSL and the reaction conditions (Fig 4). Natural GSs and their derivatives possess biocidal activity and show toxicity to a range of soil borne as well as plant pathogens and pests
(Lord et al., 2011). GSs rich plant sources and extracts with the ability to inhibit the growth of pathogens, offer the opportunity to explore them in controlling many plant diseases and as potential bio fumigants
(Sotelo et al., 2015). GSs and glucosinolate hydrolysis products (GSHPs) volatiles, too, such as ITCs, have at low concentrations been used to control plant pathogens and/or are included as active ingredients among synthetic commercial nematicidal compounds. In addition, GSs and GSHPs have shown great potential as anti-inflammatory agents through their ability to suppress inflammatory mediators independently or with other substances
(Rajan et al., 2016). GSHPs, mainly volatile ITCs, demonstrate potential in anti-hepatotoxic activity. They include gluconapin, glucoerucin and glucoraphanin that display above 53% acetylcholinesterase (AChE) inhibitory activity in a dose-dependent manner
(Blazevic et al., 2013). In addition to natural GSs, synthetic GSHPs and their derivatives also show good cholinesterase inhibitory activity. This has been illustrated in phenyl ITCs and its derivatives that display the most promising inhibitory activity with potential applications in treating Alzheimer’s disease
(Burcul et al., 2018).
