Zpracování kokosového oleje
Modified coconut oil (MCO)
- From the glycerolysis of virgin coconut oil (VCO) and glycerol
- Under various conditions
- Should have different amounts of bioactive fatty acids (FAs) and acylglycerols (AGs)
- Lauric acid (LA)
- monolaurin (ML)
- Dilaurin (DL)
- Trilaurin (TL) in MCO
www.ncbi.nlm.nih.gov/pubmed/30265940
Virgin coconut oil (VCO)
- Usually extracted from fresh coconut
- Using a low-heat process
- no chemicals
- Zachovává tak:
- Polyphenols,
- Fatty acids,
- Sterols
- Tocopherols in the oil [8]
- Coconut oil obtained from the coconut tree (Cocos nucifera)
- Extensive use in tropical and subtropicals regions
- Coconut oil traditionally produced in West Africa
- Crushing and pressing copra to extract the oils
- In large mills [4]
Extrakce z kokosového mléka
- VCO is commonly manufactured from coconut meat (wet kernel)
- By natural or mechanical means
- Without or with the application of heat
- Chemical refining, bleaching, or deodorizing methods are omitted
- Therefore, the nature of resulting VCO is not changed (Villarino, Dy, & Lizada, 2007)
VCO
- Coconut milk emulsion stability is generally governed by some proteins in the aqueous phase (Peamprasart & Chiewchan, 2006)
- Collapse of coconut milk emulsion is required
- To maximize the yield of VCO
- Emulsion of coconut milk must be collapsed to a high degree
- Oil can be released and separated effectively
- VCO from the wet extraction process
- Destabilization of coconut milk emulsion has been implemented via several processes
- Physical extraction
- Fermentation
- Enzymatic extraction (Raghavendra & Raghavarao, 2010) [30]
- By either hot or cold pressed techniques
- Method used is reported to influence the quality and grade of the oil
- Both wet and dry methods are used
- Some approaches also involve solvents for the final extraction, if using coconut expeller cake
- VCO, manufactured using controlled temperature (hot or cold) methods are thought to be the most effective methods
- To retain the highest levels of biologically active components:
- Tocotrienols
- Squalene (hydrocarbon, important for animal steroid formation)
- Tocopherols
- Sterols (phytosterols) [9]
- VCO can also be considered as a functional food supplement [9]
Copra oil
- Derived from the dried coconut meat or kernel
- Processed with no temperature control [9]
A High-Fructose-High-Coconut Oil Diet
- Induces Dysregulating Expressions of Hippocampal Leptin and Stearoyl-CoA Desaturase, and Spatial Memory Deficits in Rats.
- Thirty-two male Wistar rats were divided into 3 groups for 20 weeks
- Control group (n = 8)
- High-fructose soybean oil group (37.5% of fat calories, n = 12)
- High-fructose coconut oil group (37.5% of fat calories, n = 12)
- Coconut oil group exhibited significantly higher
- Serum fasting glucose,
- Fructosamine,
- Insulin,
- Leptin,
- Triglyceride levels
- Hippocampal leptin expression and leptin receptor mRNA levels were significantly lower
- SCD1 mRNA was significantly higher in rats fed the high-fructose-high-coconut oil diet [23]
- Compared to those of the control and soybean oil groups [23]
Buď měli olej žluklý / tepelně zpracovaná - hydrogenovaný / nebo je kombinace s vysokým obsahem fruktózy fakt nevhodná a dokáže zvrátit benefity kokosového oleje.
Dokážu si představit, že když do svalové buňky vtrhne ketolátka z kokosového oleje a chce být mentabolizována v Krebsově cyklu a ještě se k tomu přidá fruktoza, která si také vynutí spálení v Krebsově cyklu, že to bude působit prozánětlivě obojí a že pokud v oleji nebude dost protizánětlivých složek, či chybějících kofaktorů Krebsova cyklu, že to nebude dobře. Tím pádem jiné oleje, které nejsou bohaté na MCT a nezatíží buňku tolik roztáčením Krebsova cyklu, který nemusí být zcela funkční, že pak mají lepší výsledek.
Rozdíly v typech kokosového oleje
- Total phenolic content of VCO
- 7·78–29·18 mg gallic acid equivalents/100 g oil
- Significantly higher than that of refined coconut oil
- 6·14 mg gallic acid equivalents/100 g oil)
- no significant difference in fatty acid content among VCO, Copra and refined coconut oil
- All containing
- 92 % SFA
- 6 % MUFA
- 2 % PUFA [9]
- VCO has shown greater beneficial effects than copra oil in
- Lowering lipid levels in serum and tissues
- In reducing LDL oxidation by physiological oxidants
- Attributed to the biologically active polyphenol components present in the oil [9]
The frying performance of pure refined oils
- Olive-pomace oil (ROPO)
- Olive-pomace oil (ROPO) / refined coconut oil (RCO) (80:20)
- Compared during a frying operation of French fries at 180 °C
- ROPO/RCO exhibited a higher chemical stability than the pure ROPO
- Total polar compounds (TPC) 23.3% and 30.6% for the blend and the pure oil
- Polymers
- Trans and free fatty acids content - highest in the pure ROPO
- Anisidine value - highest in the pure ROPO [14]
- Medium-chain saturated and monounsaturated fats
- Common dietary ingredients among the Indian populations
- Effect of prolonged consumption of the fresh and thermally oxidized forms of these oils on glucose tolerance and hepatosteatosis in male Wistar rats.
- Thermally oxidized CO (TCO) and MO (TMO)
- Higher amount of lipid peroxidation products
- Elevated p-anisidine values
- Administration with fructose altered glucose tolerance and increased hyperglycemia in rats
- Elevated levels of triglycerides
- Reduced HDLc levels
- Hepatic antioxidant status was diminished
- Oxidative stress markers were elevated
- Higher incidence of microvesicles and hepatocellular ballooning
- Consumption of thermally oxidized fats may cause hepatic damage
www.ncbi.nlm.nih.gov/pubmed/28466662
Zahřívání
- Cooking oils are heated:
- Oxidation, hydrolysis, isomerisation and polymerisation
- Resulting in the formation of a variety of volatile compounds and monomeric and polymeric products
- Some of which are potentially toxic
- Acrolein
- Alpha and beta unsaturated aldehydes
- Off-flavour
- Negative effects on human health [4]
- But repeatedly heated VCO causes an elevation in BP
- Associated with a significant increase in the inflammatory biomarkers
- Vascular cell adhesion molecule-1
- Intercellular adhesion molecule-1
- C-reactive protein
- Thromboxane A2
- Significant reduction in the plasma PGI2 level [9]
Smoke point of these oils
- Temperature at which a fat or oil produces a continuous wisp of smoke
- Useful indicator of an oil or fat's suitability for frying
- General rule
- Smoke point of
- Unrefined palm oil is 235 °C
- Unrefined coconut oil is 177 °C [4]
- Smoke point is related to the
- Free fatty acid content
- Reheating (re-use) of oils is not recommended
- Used oils will contain a higher free-fatty acid content
- Consequent decrease in its original smoke point
- Result in higher emissions of volatile compounds at lower temperatures [4]
- Proper ventilation in kitchens is also beneficial
- Reducing the impact of these potentially toxic volatile compounds [4]
Production of coconut oil
Dry extraction
- Coconut is served as a raw material for coconut oil production.
- Dry coconut (copra)
- Wet coconut [30]
- Both raw materials can be used for extraction of oil
- Dry processing is the most commonly applied for extraction !!! [30]
- Clean ground copra is pressed by screw press, wedge press, or hydraulic press to release the coconut oil
- Which is subsequently subjected to refining processes, namely:
- Degumming
- Bleaching
- Deodorizing [30]
Wet extraction
- Become very popular to produce coconut oil or VCO
- Does not need the refining process
- Extraction of an emulsion (coconut milk) from the coconut meat
- The breaking of this emulsion to separate oil and protein components (Gunetileke & Laurentius, 1974)
- Superior as no high heat treatment or chemical is used
- Oil obtained has been called as VCO (Marina et al., 2009c)
- Has a fresh coconut smell that can be mild to intense
- Dependent upon the process used for extraction of oil
Physical extraction
- Gravitational separation
- Slow creaming process of an oil-in-water emulsion
- May be very slow due to the closeness between oil droplets and the aqueous phase, or due to attractive forces holding the oil droplets together (Nour et al., 2009)
- Centrifugation is used to accelerate this creaming process
- Higher rotation frequencies are allowed to separate the cream effectively
- Desirable to the simple gravitation method (Nour, Mohammed, Yunus, & Arman, 2009)
- Centrifugal separation is accomplished within a short time
- Possible to break down the emulsions by centrifugation in order to separate dispersions of fine oil droplets
- Coalesced disperse phase is separated as VCO from the water phase (Coulson & Richardson, 1991; Nour et al., 2009).
Chilling and thawing techniques
- Destabilize oil-in-water emulsion
- protein and oil can be separated from coconut cream obtained from centrifugation of coconut milk
- By chilling at 10 °C for 4 hr
- Followed by thawing at 40 °C
- Oil droplets coalesce and form the large size droplets
- Cream was centrifuged at 4880 x g for 15 min to obtain oil and the highest oil recovery (92%) was obtained at 5 °C (Raghavendra & Raghavarao, 2010).
- Combined treatments (the use of Aspartic protease at 37 °C, followed by chilling and thawing) on coconut milk yielded the highest oil recovery (94.5%).
Fermentation process
- Natural fermentation process
- Conventional method to produce VCO (Marina, Man, & Amin, 2009b)
- With normal flora, allowing the oil to separate on the top portion within 24 to 48 hr
- Separated oil can be collected [30]
- Fermentation enhances the breakdown of the emulsion, probably by microbial proteases
- Contamination with microorganisms can take place
- Coconut milk is the abundant source of moisture, carbohydrates, and proteins [30]
- Distilled water was added to fresh coconut milk at 1:1 ratio
- Baker's yeast (Saccharomyces cerevisiae) of 2.0 g was added to 1 L of the mixture as an inoculum for the fermentation process
- Coconut milk may spoil by some microorganisms
- Low quality of VCO (generally in yellow color)
- With oil recovery of 65% (Mansor et al., 2012) [30]
- Major drawbacks of fermentation process are
- Fermented odor
- Low oil recovery (Raghavendra & Raghavarao, 2010)
- Lipolytic enzymes in the presence of water could produce high free fatty acid (FFA) [30]
- Coconut milk emulsion can also be destabilized by adjustment of pH between pH 3 and 5.6 and added with bacterial cultures (Chen & Diosady, 2003)
- Lactobacillus plantarum
- At 70 °C for 6 hr under semicontrolled conditions
- Yield of VCO was 95.06%
- 45 °C, pH of 5, inoculum (Lactobacillus plantarum 2%), fermentation time of 48 hr
- Anaerobic conditions was found as an optimum condition for the induced fermentation process of VCO (Satheesh & Prasad, 2014) [30]
Enzymatic extraction
- Enzymatic pretreatment has been known as a potential means to obtain the high yield of oil (Marina et al., 2009b)
- Enzymatic hydrolysis process (Senphan & Benjakul, 2016)
- Most promising method among all processes for extracting oil from coconut milk (Tano-Debrah & Ohta, 1997)
- Mediated by proteases
- Effectively destabilize the coconut emulsion and release the oil (Rahayu, Sulistyo, & Dinoto, 2008)
- Use of enzyme can shorten the extraction time of VCO
- 0.075% (w/v) pectinase
- 0.05% (w/v) protease
- 0.05% (w/v) amylase [30]
- Resulted in high extraction yields (76.4%) of oil
- Compared with a nonenzymatic process yields less than 20% (Barrios, Olmos, Noyola, & Lopez, 1990)
- Coconut milk was added with papain (0.1%, w/w)
- Stand for 3 hr at 55 °C
- Centrifugation at 4900 x g for 25 min
- Collect the oil
- Recovery was 65% (Mansor et al., 2012) [30]
- Neutrase 1.5 MG (0.3%, w/w) and Viscozyme L (0.6%, w/w) at pH of 7
- Temperature of 60 °C
- Total incubation time of 30 min [30]
- Maximum extraction yield of oil (Sant'Anna, Freitas, & Coelho, 2003)
- Enzyme mixture (?-amylase, cellulase, protease, and polygalacturonase) at 1% (w/w) and pH 7.0
- Extraction temperature of 60 °C [30]
- The 73.8% of oil recovery with fine quality of oil were gained
- Proteases from shrimp hepatopancreas
- Reduce the cost of VCO production [30]
- Crude protease extract
- From hepatopancreas from Pacific white shrimp; 10 unit/g protein
- For 6 hr at ambient temperature had the maximum yield of oil (92.39%) [30]
Aged coconut oil with a high peroxide value
- Induces oxidative stress and tissue damage in mercury-treated rats.
- Exposure to mercury (Hg) and the ingestion of peroxidized edible oil represent a health risk.
- The level of MDA in the kidney and liver homogenates was significantly increased in the HgCl2, CO, and CO+HgCl2 groups when compared to control values
- Liver
- SOD activity and GSH level were increased
- CAT activity was decreased [13]
- Kidney
- GSH level and SOD activity were decreased
- CAT activity was increased in the CO and CO+HgCl2 - compared to control values
- Increased
