London, Apr 15 (IANS): Some components of the onion have antioxidant and anti-microbial properties, making it possible to use it to preserve food, says a new study.

"The antioxidant and anti-microbial properties of the raw onion make it a good candidate for use in food preservation," says researcher Jonathan Santas from the department of nutrition and bromatology at the University of Barcelona (UB).

Santas co-authored the study at the department of agrifood engineering and biotechnology at Polytechnic University of Cataluna (UPC).

The study shows that the flavonoids of onion, in addition to having beneficial properties for health, increase the life of foods, and so "they are a natural alternative to artificial additives used in food industry".

The results confirm that the yellow variety in particular is "a good source of these types of substances and there is a positive correlation between the presence of flavonoids and their antioxidant capacity.

"The onion can be effective for delaying lipid oxidation in emulsions of oil and water - a model system of foods like margarines and mayonnaises - and it inhibits the growth of micro-organisms that alter foods," Santas says.

The scientific team analysed onions of the white and yellow varieties.

The researchers demonstrated that phenolic compounds in the onion prevent the development of bacteria, micro-organisms typically associated with the deterioration of foods, said an UB release.

Previous studies indicate that flavonoids have beneficial effects for health due to their antioxidant, anti-inflammatory, cardio-protective, vasodilatory and anti-carcinogenic properties.

The study was published in the International Journal of Food Science and Technology.