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CURCUMIN : THE GOLDEN PIGMENT
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Saturday, 02 April, 2016, 08 : 00 AM [IST]
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Varsha Nair
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fiogf49gjkf0d Turmeric the most commonly available spice in the Indian subcontinent has its origin in a plant called Curcuma Longa. The curcuminoids, natural phenols present in turmeric, impart yellow colour to it.
There are three different cucuminoids present in turmeric among which Curcumin is the principal component with respect to the concentration and the other two are named as desmethoxycurcumin (DMC) and bis-desmethoxycurcumin (BDMC).
Curcumin has a bright yellow colour and often has application as a food colouring agent and natural preservative in Indian culinary. With regard to the wide application of Curcumin as food additive it has been assigned an E number as E 100.
Curcumin is popular for its antioxidant properties but its use is often restricted due to its poor bioavailability. Curcumin also has an excellent anti-inflammatory benefit which plays a major role in Alzheimer’s disease. Apart from natural food colour, Curcumin has potential application in medicine, dyes and cosmetics. Due to its varied uses, Curcumin is often known as the “ideal spice of life.”
Bioavailability of Curcumin
Curcumin exhibits poor bioavailability and the potential factors responsible for this is its insolubility in water and limited absorption. Some studies reveal that black pepper (piperine) can greatly enhance curcumin absorption.
Curcumin Extraction
To isolate the active curcuminoids from turmeric extraction is required. The extraction of turmeric yields oleoresin which comprises volatile oil, resins and about 2 – 8% curcuminoids. These curcuminoids are further subjected to separation using organic solvents which have high solubility - known as “Solvent Extraction.” The widely used solvents include ethanol, methanol and acetone. Depending on the end- application of curcuminoids there is restriction to the use of solvents that can be used. Thus if Curcumin is to be used in foods, ethanol and isopropylalcohol are the permitted solvents that can be used for extraction. Further recovery of active Curcumin occurs by solvent evaporation.
Curcuminoid solubility is dependent on the temperature and pressure of extraction process and not merely on the composition of the mixture. High ratio of solvent to raw material in solvent extraction methods yielded larger curcuminoids but reduce significantly as solvent flow rate is increased thus limiting the throughput. Hence need for an extraction method arose, which not only gave a stable product but also enhanced the purity of the end-product i.e. Curcumin. And so one of the most widely used extraction process now-a- days which has truely proven to be a boon for Curcumin extraction and meets the above-mentioned requirements is known as Supercritical Fluid Extraction (SCFE). A comparative study between conventional solvent extraction and supercritical fluid extraction showed a larger yield of curcumin can be obtained by the later extraction process. The conventional extraction methods requires more time and there is an increased risk for curcumin stability due to temperature elevation.
SCFE is the process of separating one component from another (the matrix) using supercritical fluids as the extracting solvent. The technique resembles Soxhlet extraction method except that the solvent here is supercritical fluid, substance above its critical temperature and pressure. The most adopted supercritical fluid is carbon dioxide as it has low cost, is a nonflammable compound and devoid of oxygen, thus protecting lipid samples against any oxidative degradation. Supercritical Fluid Extraction has wide applications in the field of food science, byproduct recovery from fruits and vegetables, flavour and pigment separation from spices, herbs and so on. Supercritical Fluid Extraction is currently being used for extraction of useful organic compounds from natural products and Curcumin extraction by this method can be termed as one of the best examples. Due to the fairly high solubility and maximum yield of Curcumin in supercritical CO2 and ethanol modified supercritical CO2 , SCFE is one of the most effective extraction methods for Curcumin.
Thus when compared, the following are the advantages of Supercritical Fluid Extraction than the Conventional Solvent Extraction (a) more selective extraction (b) it is less expensive in terms of solvent cost and laboratory time, (c) carbon dioxide is the major solvent which is environment-friendly with its convenient critical temperature, (d) maximum purity of end-product.
Determination of Curcumin Purity
Curcumin is widely available in market at varying cost which puts one in dilemma so as to which one to opt for though purity reports are always issued with the samples. Commercially available Curcumin extracts are usually a blend consisting of 77% curcumin (17% demethoxycurcumin, 3% bisdemethoxycurcumin, last 3% not classified but assumed to possess a cyclocurcumin content). Then how difficult would it be to recognise pure Curcumin or whether is it solvent extracted or supercritically extracted? The answer to this is quite simple and can be explained with respect to the graph diagrams shown below which gives a clear idea about the Curcumin purity when extracted by some of the traditional Solvent Extraction method and Supercritical Fluid Extraction:
The above figure represents the curcumin profile of various Solvent Extraction methods and Supercritical Fluid Extraction method alongwith the standard curcumin graph.
(A) Curcumin standard (B) Soxhlet extraction method (C) Microwave assisted extraction (D) Ultrasonic assisted extraction (E) Supercritical Fluid extraction.
Thus from the above figure it is very clear that Supercritical Fluid Extraction not only provides maximum Curcumin recovery but also has minimum or negligible presence of other curcuminoids which ensures highly pure Curcumin product with respect to the standard Curcumin profile.
Contribution of Curcumin to Indian and Global Market
Curcumin is basically used as a natural food colouring agent. Curcumin is listed for use in diary products, fats, oils, fat emulsions, edible ices, confectionery, fruits and vegetables, cereal products, meat and fish products, spices, soups, sauces, beverages, ready-to-eat savouries. Now with such wide application of Curcumin in food industry let’s have a look at how this magical ingredient can contribute to the country’s economy especially when India is one of the largest producers of turmeric.
The natural food colour industry is constantly growing especially due to increasing awareness about harmful effects and consequences of synthetic colours. Since natural colours are expensive, they are presently consumed by countries having high income strata. The reason for such an accelerating demand for natural food colours in international market is due to the ban imposed by European countries against manufacturing of synthetic colours and import of products containing such colours. Food industry is one which attracts investors all over and with the continuously growing preference for natural food colours against synthetic food colours, Curcumin can take a major place not only in the Indian market but in the world market as well. The EU has a large food industry with particular interest in natural food colours and flavours. The leading markets for natural colours in the EU are the UK, Germany, France, Italy and Spain having large food industries. Natural colours can be encouraged for use in novel products too like infant toys, crayons, organic textile printing, handmade paper rather than only food products.
As mentioned earlier, there are two methods for extracting natural colours which are Conventional Solvent Extraction and Supercritical Fluid Extraction methods. The comparative study clearly indicates that Supercritical Fluid Extraction can be one of the most promising advanced technology to extract natural colours like curcumin in the purest form. Curcumin being fat-soluble and practically insoluble in water there is a wide scope for new product development using Curcumin which can overcome these constraints and come up with water-soluble Curcumin products (heat and ph stable) which will ease the Curcumin usage and thereby pave the way for more natural colours to be introduced in the market using natural products. An association between Curcumin and other natural products along with Supercritical Fluid Extraction can have a huge potential output in the future to come.
(The author is associated with pharma industry and can be contacted at nairvarsha9@gmail.com)
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