Paper presented at the IFEAT International Conference in Barcelona, 6 - 10 November 2011 ‘Spain: Bridging Continents and Cultures’ Pages 251-258 in the printed Conference Proceedings.
NATURAL ANTIOXIDANTS IN THE PRESERVATION OF FOODS AND BEVERAGES Dr. Roger Nahas Kalsec Inc. Kalamazoo, Michigan, USA RNahas@kalsec.com INTRODUCTION The presentation is intended to give an overview on the complexity of oxidation in foods and the trends in demand for preservatives, both synthetic and natural, out of which the presentation will discuss those that are derived from herbs and spices. The presentation is also intended to share the related current challenges and insights on strategic future research and development directions.
NATURAL SPICE EXTRACTS AND ADDITIVES There is an increasing demand for safe, naturally derived food ingredients. Plant extracts can provide flavors, colors, bitter acids for the brewing industry, miscellaneous processing agents, antimicrobials, and antioxidants.
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ANTIOXIDANTS Oxidation and Classification Oxidation shortens the shelf life of foods by affecting taste, odor and color, and by changing the texture and functionality. Therefore, oxidation impacts a wide array of foods.
The classification of antioxidants is based on the oxidation steps they prevent or interfere with, so we have: primary antioxidants also known as radical scavengers, oxygen scavengers, metal chelators, quenchers of high energy species, hydroperoxides decomposers, and antioxidant regenerators.
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The History of Antioxidants Natural preservatives have been used in foods since prehistoric times without understanding the underlying chemistry. The development of antioxidants as intentional food additives began in 1920s and became a full-fledged industry in the 1940s and 1950s. Great advances were made in the middle of the 20th century in the area of plastics. Few plastic antioxidants (safe for consumption) became staples in the food industry. Eventually, there was a rise of a more skeptical attitude towards synthetic additives. This shift prompted efforts to better understand and utilize antioxidant substances found in nature.
Artificial or Synthetic? Synthetic antioxidants are cost effective and readily produced in large amounts and high purity but the introduction of new ones requires extensive safety testing which is not the case with natural antioxidants. More importantly, they have a negative consumer image. One common issue with natural antioxidants is effectiveness, as the active components usually exist amongst other plant constituents that are not active, resulting in a need to use much higher levels of the overall extract. This can affect the sensory attributes of the food. Finally, natural antioxidants are generally more expensive, because they come from botanical sources.
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Market Trends Marketing studies show a preference for healthy, functional foods, and a “back to basic”, fresh and sustainable global tastes. Additionally, clean labels and simplicity such as “No Preservatives” is on the rise.
There is a steady increase in demand for natural antioxidants over synthetic ones, with rosemary being the leading herb antioxidant extract, having a steady yearly growth.
Natural Antioxidants Family Tree Main categories of natural antioxidants are plant extracts (phenolics), tocopherols, ascorbic acid, phospholipids, citric acid and proteins.
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Extraction from Herbs and Spices The bioactive compound that needs to be isolated determines the criteria for solvent type, and extraction parameters. A resulting crude extract that could be further purified. The extraction parameters are also controlled by the desired properties such as metal chelating potential, radical scavenging activity, polarity and yield.
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Rosemary Rosemary is the dominant natural antioxidant in the market. Its efficacy is mostly attributed to its predominantly lipid soluble phenolics like carnosic acid and carnosol and water soluble rosmarinic acid. Synergistic effects have been demonstrated between rosemary extracts and other antioxidants such as citric acid, tocopherols and ascorbic acid to protect oils from developing rancidity.
Sage and Oregano With many similarities to rosemary, sage extract is an effective antioxidant for various fats and meat, but it is less commercially attractive because of its higher cost and inferior activity. Oregano has similar chemical composition in rosmarinic acid content, but lower in carnosol derivatives. The essential oil of oregano is also active due to the presence of carvacrol and thymol. Supplementing oregano oil in the diet was shown to improve the quality of the meat in chicken, lamb and turkey.
Non-Aromatic Antioxidants Some non-plant extract antioxidants are commonly used such as citric acid (natural chelators), ascorbic acid (natural, water soluble antioxidant), tocopherols (natural, oil soluble antioxidants), and tea catechins (such as EGCG).
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Essential Oils Essential oils are a mixture of compounds classified as Terpenoids. They are used as functional ingredients for foods, beverages and cosmetics. Essential oils have been known to act as antioxidants by radical scavenging mechanisms. Their main challenge is their high aroma and the undesirable effect it can have on foods where it is applied. New research is suggesting that encapsulation might be a future viable way to retain activity of essential oils and decrease their aroma at the same time. FUTURE TRENDS Data show a consumer preference for low sodium formulations, no trans fat and less saturated fats versus more omega-3s, more probiotics and more antioxidants, clean labels and of course the “natural� claim is on the rise.
CHALLENGES Complex food systems are very challenging to stabilise, on top of that, saturated, stable fats are replaced with highly unsaturated, unstable fats. Therefore, the best oxidation management strategy is the use of multifunctional antioxidant blends where each element delivers a different type of defense mechanism capable of interfering and disrupting various stage of the lipid peroxidation cycle.
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CONCLUSIONS The demand for a natural approach to stabilise food will require an increased understanding of the underlying chemistry of the oxidation of complex substances.
Dr Nahas graduated from the University of Missouri, USA with a PhD in Chemistry, the Mediterranean Agronomic Institute in Chania, Greece with Master in Chemistry of Natural Products, and the UniverstĂŠ Libanaise in Beirut, Lebanon with a Bachelor in Chemistry. He is currently R&D Director Antioxidants with Kalsec, Inc. in Kalamazoo, USA. A significant part of his research interests is focused on finding natural solutions to oxidation problems in complex food systems. Dr Nahas is the author of a number of patents, book chapters, and papers in the area of natural antioxidants and management of oxidation in foods and beverages, and has been an invited speaker at several national and international conferences.
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