多酚可以保護omega3的氧化

一份最新的研究報告顯示在營養補充品Omega -3裡添加檞皮素可以延長其保存期限。檞皮素是一種在洋蔥、蘋果和茶類裡都找的到的抗氧化多酚，其功效比在大部分魚油中合成的抗氧化物丁基羥基甲氧苯(BHT)還好，甚至比在乳化系統中的維他命E還好。漸漸的消費者越來越注重存在於水果與蔬菜裡的天然產品，所以天然的黃酮醇像檞皮素糖苷可以被用來穩定包含omega-3多元不飽和脂肪酸的食物和營養食品，如此可以提供更有價值的健康來源。研究顯示黃酮醇可以降低罹患胰臟癌的機率，調節血糖，還有預防心臟病。一份在食品化學期刊發表的文章表示，食品工業選擇天然的黃酮醇替代合成的添加物，例如在魚油裡的丁基羥基甲氧苯。

食物中的氧化作用會導致食物有味覺，顏色和外觀上的腐敗。其中以魚油最容易氧化，因為魚油含有高比例的不飽和脂肪酸。長久以來食品和營養工業一直致力在尋找天然添加物像丁基羥基甲氧苯來延續產品的保存期限。即使在油包水型乳劑裡黃酮醇的功效比丁基羥基甲氧苯差，然而在大批的魚油中卻有較高的抗氧化功效。

Polyphenols may protect omega-3 formulations

The shelf-life of omega-3 formulations may be extended by adding quercetin, an antioxidant polyphenol found in onion, apples, and tea, suggests a new study.

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.

Omega-3 stability

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.

Formulation issues

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.

資料來源: 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

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