Quercetin performed better than the synthetic antioxidant BHT (butylhydroxytoluene) in bulk fish oil, and better than vitamin E (alpha-tocopherol) in an emulsion system, according to findings published in the journal Food Chemistry.
“Considering the consumer preference for ‘natural’ products and their existence in a wide array of fruits and vegetables, naturally sourced flavonols such as quercetin glycosides could be used as effective antioxidants for stabilising omega- 3 PUFA-containing foods and nutraceuticals while providing potential additional health benefits,” wrote the researchers from Nova Scotia Agricultural College and the Memorial University of Newfoundland.
Quercetin is found in a range of foods, including capers, onions, tea, and apples. Previous studies from around the globe have reported that the flavonol may reduce the risk of pancreatic cancer, improve blood sugar regulation in diabetics, and benefit heart health by reducing blood pressure.
The new study, published in the journal Food Chemistry, indicates that formulators may use the flavonol as a natural alternative to synthetic additives, like BHT, in fish oil supplements and fortified products.
Oxidation processes in food can lead to organoleptic deterioration in taste, colour and texture. And fish products are particularly susceptible to oxidation processes because of the high unsaturated lipid content.
The food and nutrition industries have long been aware of this, and are increasingly seeking natural solutions rather than artificial additives, such as like butylhydroxyanisole (BHA) and BHT, to extend the shelf life of products.
The new study suggests that the antioxidant was “greater than that of alpha-tocopherol in the emulsions”.
However, quercetin and quercetin-3-O-glucoside did not perform as well as BHT in the emulsions of omega-3 PUFA and fish oil systems, noted the researchers.
The Canadian researchers added the flavonols, BHT, or alpha-tocopherol to bulk fish oil (Ocean Nutrition Canada), or to oil-in-water emulsions systems prepared using methyl linolenate (MLN), docosahexaenoic acid (DHA), or fish oil.
“An emulsion model system of MLN, DHA and fish oil was used to resemble food products which contain lipids dispersed in an aqueous phase oil-in-water) such as milk, salad dressings, beverages, soups and sauces,” explained the researchers.
“Although flavonols were found to be less effective in oil-in-water emulsions than, BHT, they were as effective as alpha-tocopherol,” wrote the researchers. “Interestingly, flavonols exhibited a better antioxidant activity in bulk fish oil than BHT.”
Frost and Sullivan’s European analysis revealed an omega-3 ingredients market growing at 24.3 per cent annually and projected all the way out to 2014, when it would be worth $1.6bn. This figure includes marine, algae and flaxseed sourced omega-3s.
In foods, most predictions are similarly ebullient. In a 2007 report, Packaged Facts estimated the US market was worth $2bn for foods and beverages bearing EPA, DHA and ALA either in combination or alone. Packaged Facts predicted the market would be worth $7bn by 2011.
Source: Food Chemistry
Volume 117, Issue 2, Pages 290-295
"Inhibition of oxidation of omega-3 polyunsaturated fatty acids and fish oil by quercetin glycosides"
Authors: Gwendolyn M. Huber, H.P. Vasantha Rupasinghe, Fereidoon Shahidi