Vegetable oils are extracted from various plants ranging from seeds or legumes to fruit flesh. With new processing technology improving yield, and increased number of industrial and commercial uses, their global production has increased significantly from 90.5MMT in 2000/2001 to 195.09MMT in 2017/2018 (US Department of Agriculture; USDA Foreign Agricultural Service, 2018a). Their unique chemical and physical properties attribute varied nutritive qualities and lead to numerous food and non-food uses, ranging from baked goods to medical commodities, cosmetics and biofuels.
Global Production and major producing countries
Coconut oil (CO) is among the most produced vegetable oils nowadays. Originating from the cocos nucifera, it is mostly produced in Asia (88.4%), with the major producers being the Philippines, Indonesia, India and Vietnam between 2007-2014 (FAOSTAT, 2018). The global coconut oil production has averaged 3.342 MMT (million metric tons) from 2007-2014 (see Table 1.), with a current global production of 3.44 MMT in 2017/2018 (FAOSTAT, 2018; US Department of Agriculture; USDA Foreign Agricultural Service, 2018b).
Processed coconut oil products can be classified as VCO (virgin coconut oil), CO (RBD: refined, bleached and deodorized), white oil (higher FFA), and industrial oil (crude).
CO processing may go through two different methods: dry and wet processing. Dry processing involves drying the coconut meat and then extracting via pressing or solvent extraction (resulting in crude oil), then refining to produce unrefined coconut oil. The wet processing bypasses the drying step then separating the protein from oil phases via pre-treatments or centrifugation resulting in refined coconut oil (Marina, Che Man et al., 2009). This method presents more complicated processing and results in lower yield (Gopala Krishna, Raj et al., 2010).
VCO results from cold-pressing oil extraction 24-48h (or enzymatic or solvent extraction) after harvest through GMP, avoiding oxidation triggers (light, O2 and heat) (Verallo-Rowell, Dillague et al., 2008). Some key differences between VCO and RBDCO include elevated total phenolic compounds in VCO (Marina et al., 2009).
The FA (Fatty Acid) profile of CO presents high saturated fat (90%), with approximately 60% in the form of MCT (6-12C length FA). The major FA is lauric acid (C12:0), representing 47.9% of total FAs (Sajjadi, Raman et al., 2016). Its high SFA content explains its physical characteristics including oxidative stability and a melting point of 24-27°C, above which it remains solid (Bhatnagar, Kumar et al., 2009; Ibrahim, 2000).
The remaining unsaponifiable components are polyphenols including tocopherols, caffeic acid, p-coumaric acid and catechin as well as phytosterols (F. M. Dayrit, 2015; Gopala Krishna et al., 2010). However, the method of extraction induces phenolic compound content variation (i.e. hot extraction promote increase phenolic content)(Gopala Krishna et al., 2010).
A unique property of CO is its high lauric acid content. This MCT renders the oil rapidly absorbed, bypassing liver metabolism and releasing its energetic potential without being stored as fat (F. M. Dayrit, 2015). MCTs are metabolized differently from LCT: 30% absorbed directly through intestine into portal vein. This leads to fast absorption and use with no need for esterification to carnitine (required for LCFA absorption), and free diffusion into mitochondria (F. M. Dayrit, 2015; Gopala Krishna et al., 2010; McCarty & DiNicolantonio, 2016).
Additionally, the MCT positions on the glycerol backbone influences the rate of hydrolysis, rendering it faster if at the sn-1 or sn-3 positions. With 54.3% of lauric acid at these positions, absorption is rapid and little is stored in the liver (F. M. Dayrit, 2015). Once in the liver, lauric acid metabolism follows many patterns: β-oxidation (producing acetyl-CoA for the TCA cycle), producing ketone bodies that can be readily utilized by the brain and tissues.
This oil has been used for many years in the tropical countries for cooking due to its flavour and stability at high temperatures. Increased world use of the oil has seen its physical properties used in processed foods such as confectionary, margarines, baked goods (Gopala Krishna et al., 2010; Ibrahim, 2000). Its short melting range (due to its FA composition) is a beneficial characteristic for the production of coating materials (Ibrahim, 2000). Its MP makes it an appropriate substitute for butter and cocoa butter in pastries and ice cream production.
The primary non-edible application of coconut oil is for soap-making due to its methyl esters (Gopala Krishna et al., 2010; Oluwatoyin, 2017). According to the FDA, coconut oil is the product with the most amount of uses (626) with concentration from 0.0001-70% (Burnett, Bergfeld et al., 2011). It is used in the cosmetic industry due to its emollient properties and inhibition of UVB effects (See Table 4.). Its moisturizing properties have served as bases for hair treatments inhibiting hair breaking and promoting healthy hair (Gavazzoni Dias, 2015). It has also been used as a cleanser, foaming agent and stabilizer (Burnett et al., 2011).
Recent technological developments have allowed for vegetable oils to serve as fossil fuel alternatives (Eryilmaz, Yesilyurt et al., 2016). This requires transesterification/alcoholysis to break them down into glycerine and biodiesel (Chouhan & Sarma, 2011). This includes coconut oil, reaching a yield of 90.3%, while using /2 as a catalyst (Chouhan & Sarma, 2011). Its minimal sulphur content would lead to reduced SO2 emissions (Abdulkareem, Odigure et al., 2010; Sajjadi et al., 2016).
CO has found use as a treatment for eczema due to its emollient and antiseptic qualities minimizing clinical (SCORAD) and instrumental flare-up parameters (TEWL, skin capacitance)(See Table. 3). Additional studies suggest that the monolaurin fraction may be the origin of its antimicrobial and antiviral nature (Oyi, Onaolapo et al., 2010; Verallo-Rowell et al., 2008).
Coconut is often used in a medical context as its MCT content presents qualities relating to easy digestion and absorption. The ketone producing qualities of MCTs has been linked to therapeutic qualities in treating physiological consequences of diabetes and hypertension, presenting neuroprotective effects and mitigating issues with obesity and lipid metabolism (See Table 3.). However, further investigating is required as to its efficacy in treatment of malabsorption and hypometabolic disorders (children with CF, individuals with HIV)(See Table 3.).
Economic benefit of value-addition
The antioxidant quality of coconut oil renders it a favourable addition to vegetable oil blends by increasing their stability (Gopala Krishna et al., 2010).
Harvesting, by-products and other uses
Due to its equatorial nature, coconuts may be harvested throughout the year, thriving in sandy soils with tropical climates (Lunn, 2009). By-products include copra meal and copra expellers. These are high in fiber (47%) with protein content of 20-26%. The protein is high in Arg:Lys ratio, though inferior to that of soymeal. However, this meal is consumed as such in the producing countries. It is also used as animal feed (pig, horse, beef) while having high WBC (increasing animal satiation and decreasing hunger)(Stein, Casas et al., 2015);(Foale, 2003).
Increased coconut crops lead to many different uses of the coconut plant parts by the growers, including the palm wood, fronds and stalks. This involves the leaves used to make artisanal goods (hats, baskets…), fire timber, or structural fences (Foale, 2003). Additionally the residual coconut fiber (coir) can be used as yarn, formed into stable string and ropes (bags, upholstery). Once the fiber is removed, the residue is called cortex material and can serve in agriculture for moisture preservation (Foale, 2003).
Major uses of coconut oil can be categorized in food and non-food products with its quality and processing dictating industrial or commercial endpoints. Overall, the application of coconut oil in food results in their use in cooking (depending on melting point, smoke point, oxidative stability) and integration into novel foodstuffs such as baked goods, confectionary or oil blends. As for the non-food applications, they range from cosmetic, plastic, biofuel and medical uses.
Table 1. Global coconut oil production quantities (in tons)(FAOSTAT, 2018)
Table 2. Global coconut oil production quantities (in millions of tons)(US Department of Agriculture; USDA Foreign Agricultural Service, 2018b)
|Author||Dose / Duration||Observed group /
|(Agero & Verallo-Rowell, 2004)||Twice a day topical application for 2 weeks||N=34
CO compared to mineral oil on xerosis
|Equivalent moisturizing potential. Increase skin surface lipid levels. Improvement of xerosis.|
|(Verallo-Rowell et al., 2008)||Topical application for 4 weeks||N=26
VCO compared to VOO on AD skin
|Post-treatment O-SSI significantly decreased -4.1 (p=0.004)
Post-treatment significantly lower SCORAD index scores with treatment
|(C. S. Dayrit, 2000)
|2.4g, monolaurin, 7.2g monolaurin, 50ml coconut oil||15 HIV-infected patients||CO and monolaurin have anti-viral effect, decreasing viral load|
|(Ogbolu, Oni et al., 2007)
|Coconut oil compared to fluconazole on Candida species (in vitro)
|All candida species were sensitive to coconut oil at 100% concentration and 90% of species were at 50% concentration|
|(Cardoso, Moreira et al., 2015)||6-9 months
13ml EVCO introduced into diet
|N=2 diet with CAD N=92 with CAD 13ml EVCO diet||Significant increase in HDL-C (p=0.01), no other changes in lipid profile
Significant decrease in waist circumference
|(Mumme & Stonehouse, 2015)||Meta-analysis of 13 trials n=749||Regular diet with LCTs compared to regular diet replacing LCTs with MCTs||Significant decrease in body weight: (–0.51 kg; P<0.001), WC (–1.46 cm; P<0.001), hip circumference (–0.79 cm; P=0.002), total body fat (standard mean difference –0.39; P<0.001), total subcutaneous fat (standard mean difference –0.46; P<0.001), and visceral fat (standard mean difference –0.55; P<0.001).
No changes in blood lipid levels
|(Paoli, Bianco et al., 2014)||Ketogenic diet review||Therapeutic attributes for neuromuscular and neurodegenerative diseases:
Appropriate energy source for brain hypometabolic disorders, decrease oxidative damage from metabolic stress, increase mitochondrial pathways and decrease cytochrome-c oxidase.
|(Evangelista, Abad-Casintahan et al., 2014)||2, 4, 8 weeks N=117
|N=58 Mineral oil compared to
N= 59 VCO on individuals with atopic dermatitis
|Mean SCORAD decrease by 68.23% in treated parents and 38.13% in control (p<0.001).
Increase in post-treatment skin capacitance.
|(Khaw, Sharp et al., 2018)||N=94 50-75yr
50g daily consumption
|50g daily EVCO, EVOO, unsalted butter||EVCO increased HDL-C compared to butter (+0.18 mmol/L) or olive oil (+0.16mmol/L).
No significant increase in LDL-C in EVCO compared to EVOO (−0.04 mmol/L, P=0.74).
TC/HDL-C and non-HDL-C saw no significant difference between EVOO and EVCO.
Table 3. Coconut oil studies
|(Gavazzoni Dias, 2015)||Coconut oil||Prewash and post-wash||Reduce protein loss.|
|(Burnett et al., 2011)||Coconut oil and derivatives||Extensive list of products||Various|
|(Kim, Jang et al., 2017)||Cultured Coconut Extract||Tested on cell and human tissue cultures||Increased collagen expression, barrier-enhancing and anti-inflammatory effect on UVB produced changes|
|(Korac & Khambholja, 2011)||Coconut Oil||20% UV protection|
Table 4. Coconut oil studies relating to cosmetic use
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* This article was initially written as a paper for the Food Commodities course at McGill University.