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Rosemary The aqueous extract of rosemary contains high concentrations of phenolic substances and flavonoids. Scavenges free oxygen radicals; preventing lipid oxidation. The most active antioxidative constituents of rosemary are phenolic diterpenes and phenolic acids. It’s important to know that different varieties of rosemary grown under different conditions may vary in their content of phenolic compounds (the same can apply to other herbs/spices). Rosemary can be used in food and as animal feed additive.


Oregano Its extract contains high concentrations of phenols, primarily rosmarinic acid, as well as phenolic carboxylic acids and glycosides that are both antioxidative and effective superoxide anion radical scavengers. Essential oils of oregano and rosemary were both more effective at inhibiting Fe2+


-induced oxidation of linoleic acid in a sunflower oil model


system than BHA (Stashenko et al., 2002). Oregano is widely used in the food and feed industry – where it offers several other benefits such as antibacterial, antiviral and antifungal properties.


Marjoram Marjoram essential oil also contains a significant amount of both rosmarinic acid and carnosol. The essential oil can scavenge hydroxyl radicals. It has antiradical activity exceeding that of the phenolic component thymol. In a linoleic acid model system, at 5 mg/mL, marjoram has a radical scavenging activity of 92%, inhibits conjugated diene formation by 50%, and formation of secondary oxidation products by 80% (Schmidt and others 2008). This herb can be added to foods without adding unwanted flavours, also used in animal feed.


Sage The polar extracts of sage have strong radical scavenging ability and superoxide anion radical-inhibiting ability. It contains antioxidant


phenolic diterpene compounds such as carnosol, rosmanol, and rosmadial. However, adding sage (0.05%) to raw pork is a less effective antioxidant than feeding α-tocopherol (1000 mg/kg feed) to pigs prior to slaughter in terms of preventing oxidation in cooked pork patties (McCarthy and others 2001).


Thyme Thyme essential oil exhibits very strong free radical-scavenging ability and inhibits lipid oxidation induced by both Fe2+


/ascorbate and Fe2+ H2 O2 thyme.


Basil In basil, a significant correlation exists between the total phenolic content and antioxidant activity. The aqueous extract of basil is a concentration-dependent superoxide and hydroxyl radical scavenger. Basil essential oil (contains eugenol) strongly inhibits lipid peroxidation.


Cinnamon Cinnamon contains a number of antioxidative components including vanillic, caffeic, gallic, protochatechuic, p-hydroxybenzoic, p-coumaricd, and ferulic acids and p-hydroxybenzaldehyde. Of the 42 commonly used essential oils, cinnamon bark, oregano, and thyme have been reported to have the strongest free radical-scavenging abilities (Wen and others 2009).


Synergism Studies have shown that combining antioxidants may increase their effectiveness. For example, dietary synthetic antioxidants combined with α-tocopherol were more effective than rosemary, green tea, grape seed, or tomato extracts alone or in combination in sparing tocopherols oxidation and in preventing oxidation of fresh frozen chicken patties (Smet et al., 2008). More has to be explored to find possible synergism effects of


natural antioxidants, not necessarily in combination with synthetic antioxidants.


Concluding remarks - Antioxidants are commonly used in animal feed or as preservatives in food products. - The fact that they are natural, and have anti-oxidative activity that is as good as or better than the synthetic antioxidants, makes them particularly attractive for commercial food processors because of consumer demand for natural ingredients. - Natural antioxidants especially from plant extracts, herbs and spices are more sustainable sources, and environmentally friendly compared to synthetic antioxidants such as BHT, BHA and propyl gallate. - Adoption of natural antioxidants in the feed-food industry starts with understanding the available sources and their mode of actions – not forgetting to tap into possible beneficial effects that may arise from synergism.


PAGE 24 JULY/AUGUST 2018 FEED COMPOUNDER


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/ . Carvacrol and thymol are the main antioxidant compounds of


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