Fruit & Vegetable Magazine

Features Fruit Production
Onions an alternative to artificial preservatives


April 21, 2010
By Fruit & Vegetable

Topics

April 14, 2010 – Some
components of the onion have antioxidant and antimicrobial properties, making
it possible to use this bulb for food preservation.

April 14, 2010 – Some
components of the onion have antioxidant and antimicrobial properties, making
it possible to use this bulb for food preservation.

This is demonstrated by
researchers from the Polytechnic University of Cataluña (UPC) and the
University of Barcelona (UB) in a study that has just been published in the
International Journal of Food Science and Technology.

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“The antioxidant and
antimicrobial properties of the flavonoids 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 UB and co-author of a project
carried out in the Department of Agrifood Engineering and Biotechnology at 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 the food industry.” Flavonoids are phenolic
compounds (with the phenol group) that are synthesized by plants.

The results confirm that,
especially the yellow variety, 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 also inhibits the
growth of microorganisms that alter foods,” Santas indicates.

The scientific team
analyzed onions from the white varieties, including Fuentes de Ebro and Calçot
de Valls, and the yellow variety Grano de Oro. Using them the researchers
demonstrated that phenolic compounds in the onion prevent the development of
bacteria such as Bacillus cereus, Staphylococcus aureus, Micrococcus luteus and
Listeria monocytogenes, microorganisms typically associated with the
deterioration of foods.

Previous studies indicate
that flavonoids have beneficial effects for health due to their antioxidant,
anti-inflammatory, cardioprotective, vasodilatory and anti-carcinogenic
properties, making it of special interest in the prevention of chronic
illnesses, such as cardiovascular illnesses, and some types of cancer.

The flavonoids of the
onion are more stable than some of its other components, such as sulphur
compounds. Traditionally, it was indicated that these sulphuric compounds are
good for the health, as they are responsible for the characteristic taste,
aroma and lacrimogenic effects of the plant. These substances, which are very
volatile and unstable, are released when the onion is damaged or cut.