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Tuesday, April 20, 2010

ONION FLAVONOIDS-THE BACTERIA "BASHERS"!


Who ever has not experienced the tear jerking effect of onion when it is cut during preparation of many foods containing this root vegetable? In spite of this nuisance onion is liked universally by one and all because of its characteristic flavor and aroma imparted to foods. Besides some of the sulfur containing compounds present in onion have healthy properties. Now comes the report that the flavonoid chemicals contained in this popular vegetable has antioxidant and antibacterial capabilities not known earlier making onion a very desirable component of daily diet. That onion is a regular item of consumption in Mediterranean diets, considered one of the healthiest in the world, adds up to its credentials as a well being food. Globally onion production stands at a staggering 66 million tons providing an average annual per capita consumption of about 10 kg, a significant quantity to confer the health benefits attributed to onion.

"The study, that has just been published by the International Journal of Food Science and Technology, 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) which 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 analysed onions of the White varieties "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".

No wonder onion is a regular component in many vegetable salad combination where it is included in its raw form. In traditional meals in many parts of India, onion, cucumber and sliced lime or lemon are routinely served, probably realizing the well being attributes of these vegetables to supplement a complete meal. Since the report is published in a peer reviewed journal, the basic scientific premise may be valid. But whether these properties are universal for all varieties of onion needs to be elucidated. Also in many traditional practices onion is sauteed or heated at high temperatures for generating artifact flavors liked by many and it is known whether the flavonoids are stable at such temperatures.
V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

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