improving wine quality, natural antioxidants

8/4/2019 Improving Wine Quality, Natural Antioxidants

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IMPROVING THE QUALITY OF WINE:

NATURAL ANTIOXIDANTS

Dr. Vincenzo Longo, Director of the Pisa Section of the National ResearchCenters Biology and Agricultural Biotechnology Institute

The goal of lowering the sulfur dioxide levels in wines is a feasible one thanksto careful and well- monitored vinification techniques, and also through the useof substances that substitute for the typical antioxidant function of SO2 and itsderivatives, but which are non-toxic. To do this, it is possible to select naturalcompounds or extracts that have an antioxidant and antiseptic function andare not toxic.

The antioxidant power of these selected compounds and extracts is measuredby the ORAC (Oxygen Radical Absorbance Capacity) method, which allows oneto quantify the protective action of an antioxidant.

DETERMINATION OF THE TOTAL ANTIOXIDANT CAPACITY OF A FOOD

The antioxidant power of foods of vegetable origin is due to a vast range ofmolecules such as vitamins C and E, polyphenols, carotenoids, terpenoids,trace elements, etc. The principal antioxidants are polyphenols, followed by

vitamins and carotenoids. The quantity of antioxidants in foods of vegetableorigin and, therefore, their associated antioxidant potential, depends mainly onthe variety and degree of ripeness. Various post-harvest aspects, such asconditions of storage and conservation (time, temperature, modifiedatmosphere, etc.) and of the actual production process (blending, time andtemperature of possible treatments, addition of synthetic antioxidants, etc.)impact on the antioxidant capacity of foodstuffs of vegetable origin. (Manzoccoet al., 1998; Olsson et al., 2004; Srivastava et al., 2007).

Antioxidant capacity can be a key parameter both for food scientists and for

those engaged in technical and nutritional study. There is therefore a need todevelop a standard methodology for measuring Total Antioxidant Capacity(TAC).At present, the most reliable method is that of ORAC (Oxygen RadicalAbsorbance Capacity).One ORAC unit corresponds to the antioxidant power of a 1 mol solution ofTrolox (a noted antioxidant).Today researchers are attempting to determine how many ORAC units areneeded for an organism to be healthy and to contrast the degenerativeprocesses that are the basis of cellular ageing and of some major pathologies.

IMPROVING THE QUALITY OF WINE: NATURAL ANTIOXIDANTS

Dr. Vincent Longo, Responsible of the Section in Pisa of the Institute of Biology and AgrarianBiotechnology, CNR


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The ORAC scale is used by nutritionists to identify which foods offer a highercapacity of absorption of free radicals. The more a food can neutralize freeradicals, the higher the ORAC value.

DESCRIPTION OF THE ORAC METHOD

The ORAC method is a system that is able to determine the antioxidant powersof polar and non-polar compounds. The antioxidants react with peroxyl radicals(pro-oxidants) in the presence of fluorescein, which reveals that a reaction isindeed taking place. As long as the antioxidants are able to capture theradicals, they protect the fluorescein from deterioration; once the effect of theantioxidants is exhausted, the radicals react with the fluorescein, which thenloses fluorescence. The amount of time the fluorescein takes to degrade isproportional to the quantity and to the activity of the antioxidants present in

the sample. The numeric value of the ORAC units is expressed in mols ofTrolox equivalents and is calculated comparing the curve of degradation withthat of Trolox, a water-soluble vitamin E equivalent that acts as a standard.

HOW NATURAL ANTIOXIDANTS COUNTERACT THE EFFECT OF FREE

RADICALS

Oxidation and free radicals are well known and are amply described inscientific literature. It is well established that an intense oxidative processleads to cell damage. Preventing or limiting such damage enhances humanhealth.

Oxygen is fundamental for life but at the same time it is a strong oxidant; thisaction can be held in check by antioxidants. Among the antioxidants thereexists a family of chemical compounds called flavonoids (polyphenols). Around4000 flavonoids have been identified in nature, constituting a superior class ofantioxidants, and they seem to be responsible for the major part of the powerto remove oxidizing substances provided by fruit and vegetables.

In recent times consumers have become very aware as to which foods containantioxidants. Doctors and nutritionists advise a diet that is rich in fruit andvegetables because these foods offer a notable quantity of these scavengers

of free radicals; chocolate is also a food that is very rich in such substances,but so are tea and red fruits a cup of green tea (150 grams) supplies 1880ORAC units, and a serving of red grapes (150 grams) 1950 ORAC units.

A diet that includes large quantities of these nutrients could counteractdegenerative and cardiovascular diseases and cancer. Studies have also beencarried out on the relationship between foods and the aging process. Amongthe most important research is that conducted by the United StatesDepartment of Agricultures Human Nutrition Research Center and by TuftsUniversity in Boston. The results of these studies suggest that consuming fruit




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and vegetables with high ORAC values can help slow down the aging process inboth the body and the brain.

ORAC: DAILY REQUIREMENTS

It has been estimated that every person should consume 3000-5000 ORACunits each day in order to fully enjoy the benefits of their antioxidant contents.

A study conducted by Tufts University in Boston involved 36 men and womenbetween the ages of 20 and 80. All of them in the year preceding the studyconsumed 5 portions a day of foods rich in antioxidants. During the study theservings were doubled to 10 a day. Before the study, the participantsconsumed an average of around 1,670 ORAC units daily; increasing their intaketo 10 servings, the ORAC levels established themselves at between 3,300 and3,500 units a day: around double the previous antioxidant capacity provided bythe foods. Also, in another study at the University of Boston, it was noted thata diet that is particularly rich in antioxidants can increase the ORAC value inthe blood by 13 to 25%.

This document was published by

www.freewine.euSeptember 2011

Freewine is a set of guidelines, to be put into effect by following a non-bindingtechnical protocol. The aim of these guidelines is to reduce considerably the quantityof sulfites added to the wines produced by the companies taking part in the project.


http://www.freewine.eu/http://www.freewine.eu/

improving wine quality, natural antioxidants

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