Natural Antioxidants-Sources and Applications

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In The Name of ALLAH, The Most Merciful, The Mast GraciousSeminar in Environmental BiochemistryEnvironmental Studies MSc.- Aut. 2013

Natural Antioxidants: Sources and ApplicationsSupervised By:Dr. Sabah GaberPresented By:Dalia ElsayedIntroduction" " 29" " 172

Since 1994, consumers have expressed concern about the safety of preservatives and additives in their food. More than 12 y ago, Sloan (1999) reported that one of the top 10 trends for the food industry to watch included the sales of natural, organic, and vegetarian foods. There is a clear trend in consumer preference for clean labeling, for food ingredients and additives that are organic/natural with names that are familiar, and that are perceived to be healthy. In addition, the call for sustainable sources and environmentally friendly production is forcing the food industry to move in that direction.Oxidation and Antioxidants

Oxidation is a chemical reaction that can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves.

An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules.AntioxidantsAntioxidants are compounds or systems that delay autoxidation by inhibiting formation of free radicals or by interrupting propagation of the free radical by one (or more) of several mechanisms.

Natural Antioxidants

Food tissues, because they are (or were) living, are under constant oxidative stress from free radicals, reactive oxygen species, and prooxidants generated both exogenously (heat and light) and endogenously (H2O2 and transition metals). For this reason, many of these tissues have developed antioxidant systems to control free radicals, lipid oxidation catalysts, oxidation intermediates, and secondary breakdown products. These antioxidant compounds include flavonoids, phenolic acids, carotenoids, and tocopherols that can inhibit Fe3+/AA-induced oxidation, scavenge free radicals, and act as reductants.

Spices and herbs, used in foods for their flavor and in medicinal mixtures for their physiological effects, often contain high concentrations of phenolic compounds that have strong H-donating activity.ORAC ValuesMany natural antioxidants have high ORAC values- antioxidant capacity in vitro and so provide an artificial index of antioxidant strength.The oxygen radical absorbance capacity (ORAC) method is based on the inhibition of the peroxyl-radical-induced oxidation initiated by thermal decomposition of azo compounds.

Antioxidative plant phenolics Groups

The major antioxidative plant phenolics can be divided into 4 general groups: 1- Phenolic acids (gallic, protochatechuic, caffeic, and rosmarinic acids) found in plant extracts.2- Phenolic diterpenes (carnosol and carnosic acid) found in plants.3- Flavonoids (quercetin and catechin) found in plant extracts.4- Volatile oils (eugenol, carvacrol, thymol, and menthol) found in plant extracts.

Phenolic acids generally act as antioxidants by trapping free radicals; flavonoids can scavenge free radicals and chelate metals as well.Mechanism of Antioxidants action

(1) scavenging species that initiate peroxidation. (2) chelating metal ions such that they are unable to generate reactive species or decompose lipid peroxides. (3) quenchingO2preventing formation of peroxides. (4) breaking the autoxidative chain reaction.(5) reducing localized O2concentrations.Natural Antioxidants from Chemical ViewThe natural antioxidants AA and -tocopherol each have 1 aromatic ring as well. However, many of the natural antioxidants (flavonoids and anthocyanins) have more than 1 aromatic ring. The effectiveness of these aromatic antioxidants is generally proportional to the number of OH groups present on the aromatic ring(s). Depending on the arrangement of the OH groups, these compounds may also chelate prooxidative metals. The facts that they are natural, and have antioxidative activity that is as good or better than the synthetic antioxidants, makes them particularly attractive for commercial food processors because of consumer demand for natural ingredients.

Herbs

A number of spices and herbs contain compounds that can be Removed and added to food systemsto prevent oxidation. Antioxidant (and flavor) components of herbs and spices may be removed/concentrated as extracts, essential oils, or resins.

Ginger, and cumin

Ginger is derived from the root of Zinger officinale. Fresh and dried ginger contain relatively large amounts of the volatile oils camphene, p-cineole, alpha-terpineol, zingiberene, and pentadecanoic acid. The maximum total phenolic contents were extractable with methanol from fresh ginger (95.2 mg/g dry extract) followed by hexane extraction of fresh ginger (87.5 mg/g dry extract). Ginger extract has been shown to have antioxidant activity almost equal to that of synthetic antioxidants.Cumin is derived from Cuminum cyminum. The major components in cumin volatile oil are cuminal, -terpinene, and pinocarveol (El-Ghorab and others 2010). Cumin essential oil is better at reducing Fe3+ ions than dried or fresh ginger or cumin.

Extraction

Because many antioxidants are unstable to oxygen and endogenous enzymes, most are extracted from freeze-dried plant materials.Three primary extraction techniques are used for polyphenols: solvents, solid-phase extraction, and supercritical extraction. Using a Soxhlet apparatus combines percolation and immersion that increasesextraction efficiency. Several extractions can be accomplishedwith solvents having different polarities (petrol ether, toluene, acetone, ethanol, methanol, ethyl acetate, and water).

Effect of Processing

Endogenous antioxidant systems (enzymatic) can be damaged during food processing (particle size reduction and heating), by certain ingredients (salts and organic acids), and by storage conditions (presence of oxygen) such that they are ineffective (Chen and others 1998). NaCl, in particular, reduces the activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase that reduces their capacity to perform antioxidative functions (Lee and others 1997). Ingredients, such as AA and citric acid, can work synergistically with flavonoid antioxidants.

Spices and herbs can be added to foods in various forms: whole, ground, or as isolates from their extracts.

Practical Approaches and reecommendationsIt is a call for GREEN LIFE..Effects of the food matrix and ingredientsNatural plant antioxidants can protect food components from oxidation under the stress of heating and storage.Adding antioxidants to livestock dietsIncluding herb distillates into livestock diets can have positive effects. Fresh meat from these animals had higher total ferric reducing antioxidant power and lower DPPH values than controls indicating that the rosemary distillate partitioned into the meat tissues and reduced susceptibility to oxidation.i.e. Improving lipid stability.References and LinksNatural Antioxidants: Sources, Compounds, Mechanisms of Action, and Potential Applications- M.S. Brewer- Comprehensive Reviews in Food Science and Food Safety- Volume 10, Issue 4, pages 221247, July 2011http://onlinelibrary.wiley.com/doi/10.1111/j.1541-4337.2011.00156.x/full

Natural Antioxidantshttp://www.healthylifestylefactors.com/naturalantioxidants.htm

Images linkshttp://www.examiner.com/article/collecting-your-own-herb-seedshttp://fluorous.com/flle.phphttp://evieevan.com/beauty-insights/skin-care/what-is-an-antioxidant/http://wisechoiceliving.com/its-radical-part-1/http://www.antioxidants-make-you-healthy.com/benefits-of-antioxidants.htmlhttp://www.al-health.net/%D8%AE%D8%B5%D8%A7%D8%A6%D8%B5-%D8%A7%D9%84%D8%B2%D9%86%D8%AC%D8%A8%D9%8A%D9%84-%D9%85%D8%B6%D8%A7%D8%AF%D8%A9-%D9%84%D9%84%D8%A7%D9%84%D8%AA%D9%87%D8%A7%D8%A8/http://lovelyhealthylife.com/2010/10/09/antioxidant-power/http://www.aromaoilstore.com/cumin-seed-essential-oil.htmlMay ALLAH Rewards You

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