This paper has been published by the Journal Consomer Eroski, Eroski Foundation, which was performed the next copy.

Onions, new natural preservative

The presence of flavonoids in onions makes this an important food preservative naturally

Onion is one of the foods used in cooking and more possibilities: can be eaten raw, cooked, caramelized, grated or chopped. But their applications are not just culinary. From a nutritional standpoint, include diuretic and cleansing properties. It is also a remedy for respiratory ailments such as coughs, colds and bronchitis and is an effective disinfectant. Consuming raw protects the body from infection. It is digestive, anticancer, aphrodisiac and bactericide. What's more, it also has excellent antimicrobial properties that make it a perfect candidate for use as a natural preservative.

- Image: Ruben Garcia / Consumer Eroski -

Plants, seeds and fruits are rich in flavonoids, phenolic compounds known for their beneficial effects, such as antioxidant, antiinflammatory, antiviral and antiallergic. Onion is one of the foods rich in flavonoids and therefore has antioxidant and antimicrobial properties described. These features allow for use in the food technology as natural preservative agents, especially the yellow onion, an excellent source of flavonoids and an important antioxidant, according to a study conducted by the Department of Nutrition and Food Science Universitat de Barcelona (UB) and the Department of Agricultural Engineering and Biotechnology of the UPC. Preservative action is synonymous with a longer life of foods. Preservatives may be natural or artificial. Both perform the same function, but they tend to use more and more the former.

Rust

The oxidation of lipids is a major problem of food. It is a chemical phenomenon that causes a significant loss in quality and safety. The use of onion retards this oxidation and prevents the growth of pathogens. For research, experts have conducted an analysis of the different varieties of onion and determined that phenolic compounds contained in them are able to inhibit the growth of pathogenic microorganisms. The study was effective against the growth of bacteria such as "Bacillus cereus", "Staphylococcus aureus", "Micrococcus luteus" or "Listeria monocytogenes", four of the most common pathogens in food spoilage.

Lipid oxidation causes a significant loss in quality and food safety

We analyzed the variety of Fuentes de Ebro white onion, an onion soft, tender and sweet, which is characterized by a thick stem, round at the root and elongated at the neck. This onion has Denomination of Origin and distinctness (C) Food Quality, which identifies products and special nutritional gastronomic qualities. Another variety was studied Calçot Valls, a white onion and developed underground, so that the buried part is very tender and extreme sweetness. We also analyzed the variety of onion yellow Grano de Oro, one of the most cultivated and consumed in the world, distinguished by having a larger size and a yellow color.

The power of flavonoids

Flavonoids are compounds found in fruits, vegetables, seeds and flowers as well as in beer, green and black tea, soy and wine. In addition to antioxidants, these compounds have antifungal and antibacterial functions, give color to food and are characterized by a significant capacity to bind metals such as iron in the body. Are in the outermost portions of the plant. Among the various flavonoids, Citrus Bioflavonoids are found in onions, cherries, grapes, oranges, lime or lemon, among others. The soy, called isoflavones also are common in tofu, tempeh, soy flour or milk. The antociandinas, plant pigments responsible for red color of cherries or ellagic acid, are also in grapes and vegetables.

MORE NATURAL PRESERVATIVES

Artificial preservatives are substances particularly new. In ancient times, foods were preserved by natural vinegar, salt and different spices. Today is a much more strict and has been an increased use of artificial preservatives, although this trend is changing. Increasingly, natural substances and daily individual diet conservative play an important role. Some examples are:

• Curcumin (E100), a natural yellow coloring can also be obtained from chemical form. It is present in butter, milk, cheese or pastry.
• The lactoflavin (E101) is a yellow dye in eggs, milk, cheese and instant desserts. No risk of toxicity.
• Chlorophyll (E140), green dye from plants and present in mustards, poses no toxicity.
• Carotenoids (E160), natural dyes obtained from plants which become the vitamins in the body.
• The xanofilas (E161) are present in natural dyes pastry and not cause toxicity.
• The anthocyanins are red, purple or blue and are found in legumes. Calcium carbonate is a white and gray coloring of mineral without any toxic hazard. It is present in bakery products.

Author: By NATALIE Gimferrer MORATO

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