SPECIAL STORY FEED & ADDITIVE MAGAZINE December 2023 55 Or the mechanism can follow a different pathway and lipid radicals can be stabilized by forming an epoxy quinone. In summary, the key message here is that one molecule of carnosic acid can neutralize two lipid radical molecules.2 2 What we can learn from the chemistry explained here is that carnosic acid can generate a variety of secondary antioxidants. This unique cascade-type process is likely to amplify the antioxidative power of carnosic acid and hence of rosemary extract and to constitute an effective defense mechanism.3 In sum, the main driver for the antioxidant activity of rosemary extract is carnosic acid. This means the higher the carnosic acid concentration in a rosemary extract, the better will be its antioxidant activity. The rest of the phenolic diterpenes will also have some antioxidant activity but lower than carnosic acid because, as we have seen, they are degradation products from the carnosic acid molecule. Besides, rosemary extracts contain also other antioxidants such as rosmarinic acid bringing more antioxidant power to the overall activity of this botanical extract. OLIVE EXTRACT Olive extract is another natural ingredient very well known for its health benefits and widely used for centuries in the countries of the Mediterranean area. Apart from its health or endogenous antioxidant and antimicrobial properties, recent research has shown the potential benefit of using olive extract as an exogenous antioxidant to prevent oxidation of fats, oils and fat containing matrices. Since olives are a raw material extensively used in human nutrition, the question arose if it could be economically suitable as an ingredient for the feed and pet food industries. Not all parts of the olive tree are used at the moment for human consumption. Among others, there are the leaves and there is the waste of the olive fruit after production of olive oil. Both co-products are rich in polyphenols with potential antioxidant activity. In olive materials we can find two interesting molecules for our antioxidant purpose: oleuropein and hydroxytyrosol. These two catechols have shown endogenous and exogenous free radical scavenging activity.4 Figure 1. Proposed oxygen scavenger mechanism of rosemary extract Figure 2. Proposed hydrogen transfer mechanism of rosemary extract Figure 3. Chemical structures of oleuropein and hydroxytyrosol
RkJQdWJsaXNoZXIy MTUxNjkxNQ==