Friday, December 18, 2015

Is Turmeric's antibacterial prowess over rated? Time for a reassessment

Lately the spice or condiment known as Turmeric, used widely in India and other Asian countries has been eulogized as one of the most powerful health protectants and many claims are made in different publications regarding its properties that benefit mankind. Look at the list of diseases/disorders it is supposed to "cure" and one is struck by the diversity of ailments this humble food adjunct is capable of curing.  If the Ayurvedic system of medicine so widely adopted in India is to be relied upon turmeric can cure a host of disorders affecting skin, heart, liver and lungs. Besides turmeric is also touted as a remedy for epilepsy, bleeding disorders, skin diseases, decongestion of lungs, alterative, analgesic, antibacterial, anti inflammatory, antitumor, antioxidant, antispasmodic, appetizer, astringent, cardio vascular issues, carminative, cholagogue, digestive, diuretic, stimulant and vulnerary! Quite a mouthful! Well why this narrative now regarding a spice with 5000 years history behind it? Provocation comes from a study recently published which talks of turmeric as a powerful antibacterial, advocating resurgence of this spice as an alternative to modern antibiotics. How far such a claim is backed by scientific evidence on hand?  Look at the report emanating from one of the universities in the US which claims that curcumin can be coated on cookwares and knives to make the food cooked at home safer.  

"What if our next-generation, futuristic antimicrobial turns out to be the same thing people have been using for the last 4,000 years? A new invention could improve food safety by borrowing a trick from ancient civilizations: using spice to fend off germs. If you want to keep food from spoiling you can load it with sugar (see preserves), or salt (see pickles), or fat (see confit, or SPAM) — but then you end up with a lot of sugar, salt, and fat. You can use synthetic preservatives, or natural chemicals (like the ones you get from smoking food). You can freeze food, but then you have to keep it cold until you are ready to eat it. Another alternative is to add spices, which can inhibit the growth of harmful microbes. Garlic, onion, cinnamon, allspice, oregano, thyme, cumin, turmeric, and the chemical that makes peppers spicy are all bacteria killers. It's likely that equatorial cultures have spicier foods because the warm climate leads to faster food spoilage. The flavors that those spices lend to food is a side effect — a delicious side effect. But we don't always want everything to taste spicy. Ruplal Choudhary, a food and bioprocess engineer at Southern Illinois University Carbondale, is part of a research team that has found a way that the antimicrobial properties of the spice turmeric might be employed without making foods taste like turmeric. They discovered how to coat glass and metal with curcumin — the main antibacterial chemical in turmeric. The curcumin is embedded in nano-capsules, so it doesn't rub off and flavor foods. You could imagine using this technology to coat the insides of cans (a substitute for BPA perhaps) or knives and countertops — to provide a new line of defense against food-borne illness. Choudhary also thinks this technology could be used to make fresh produce safer. As he told the university's news service: "Where I grew up, our house was surrounded by gardens," Choudhary said. "My father never liked to eat produce that came from the store, especially if it was harvested early and ripened in transit or at the store – he said it had no taste. We know now fresher foods are also higher in antioxidants and nutritive value. My goal is to find practical ways to use this technology to preserve food freshness as well as to create antimicrobial surfaces."

If one looks at the composition of turmeric it does contain curcumin which had been studied extensively all over the world confirming its value as a natural therapeutic substance with some positive influence on human health. The standard extraction procedures using solvents like ethyl alcohol, ethyl acetate, hexane, acetone, fluid carbon dioxide can separate curcumin from dried turmeric rhizome but industrially solvent extraction is done after distilling out the essential oil through steam distillation. The oil content can vary from 2-7% depending on the variety cultivated (there are 2 dozens of varieties grown in the world). The deoiled residue yields oleoresins containing resins, less volatile oils, waxes etc from which curcumin has to be fractionated out.. Curcumin content in turmeric varies between 2-7%. The big question is what are the active principles involved in conferring antibiotic properties to turmeric powder? Most experts believe that it is the essential oil component that is responsible for this property. In turmeric essential oil there are constituents like ar-turmerone (22%), a-turmerone(26%), b-turmerone(17%), curione(24%, ar-curcumene(6.3%) and a host of others making up about 24%. Out of the 54 compounds separated more than 20 are yet to be identified. It is reported that actually turmerones and curione fractions of turmeric oil have some antibiotic properties and evidence is there about the antimicrobial property of turmeric oil against Staphylococcus aureus, Candida albicans and Aspergillus niger. The new study cited above talks of using curcumin as a coating to confer antibacterial property which needs further exploration before application. No doubt the nano technology used for coating is a novel one but how effective it is against pathogens must be independently verified.


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