Onion by-products offer antioxidant potential

Spanish researchers have found onion waste may be a powerful source of antioxidants and anti-browning agents.

More than 450,000 tonnes of onion waste are produced in the European Union each year and the researchers suggest a paste extricated from this waste could proffer up an abundant source of antioxidants usable by the food and food supplements industries.

"In this study it was shown that processing of onion wastes to obtain a paste (mixture content) and applying a mild pasteurisation were the best alternatives to obtain an interesting stabilised onion by-product with good antioxidant properties that made useful its use as functional food ingredient," the researchers at the de Investigaciones Científicas (CSIC) in Madrid concluded. The research was published in the peer-reviewed journal Food Chemistry. "Valorisation of by-products, particularly exploitation of them for profitable production of food-grade products will benefit the onion producers and processors."

In tests on Spanish onion varieties, frozen and pasteurised onion paste was found to contain high levels of quercetin and antioxidant activity.

"By-products derived from the manipulation and preparation of onion for its marketing involves a great economic loss for that sector food industry," wrote the researchers. "From this study, it could be concluded that there is a real possibility of using those onion by-products for developing natural food ingredients with functional properties.?

With consumers increasingly seeking natural alternatives when making food choices, synthetic antioxidants such as butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT) are in decline, while natural antioxidants like natural vitamin E, vitamin C and herbal extracts are increasingly in demand.

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