Rosemary and sage CO2-antioxidants extend shelf life of food naturally

Dr. Peter May, FLAVEX Naturextrakte GmbH

CO2-antioxidants from Rosemary and Sage are highly effective multifunctional ingredients for retarding oxidation of lipids, essential oils and stabilization of carotenoids. Low volatility and thus excellent carry-through-effects make them effective in low concentrations. More and more consumers are concerned about the presence of synthetic chemicals in their daily foods. Therefore the demand for natural and organic food is going up. Rosemary and Sage antioxidants meet the customers´ expectation of natural food ingredients. Since CO2 is GRAS (Generally Recognized As Safe)-approved and compatible to EU as well as USDA-NOP organic certification, CO2-Rosemary and Sage antioxidants are increasingly used in organic certified products.

Introduction
There are two main categories of antioxidants: Primary antioxidants interrupt the oxidative free radical chain reaction by contributing an electron or hydrogen from the phenolic hydroxyl groups and therefore stabilize free radicals, which do not further initiate or propagate further oxidation of lipids. Secondary antioxidants deactivate singlet oxygen, chelate metals and regenerate primary antioxidants. For better efficiency, primary antioxidants are often used in combination with secondary antioxidants (1).

A large number of natural phenolic compounds have been reported to possess high antioxidant properties. Only a few of them however are commercially applied in foods since certain requirements e.g. adequate proof of safety limit their usage. Most important commercially available natural antioxidants are tocopherols, ascorbic acid and Rosemary and Sage extracts (2,3). Synthetic antioxidants are regulated and restricted to low usage levels due to their potential health hazard whereas Rosemary and Sage antioxidants are so far considered as traditional herbal extracts. However it appears that the practice of granting E-numbers is gaining ground. Accordingly the Standing Committee on Foodstuffs stated that flavor reduced Rosemary extracts primarily sold as antioxidant are considered as food additives and as such require authorization under Directive 95/2/EC. It is expected that this comes into force in 2011. EFSA has already stated that Rosemary extracts at the proposed use levels have no safety concerns and several in vivo studies reported that Rosemary may be beneficial and even protective at various stages of carcinogenesis in animal models (4).

Extraction Process
Supercritical CO2-extraction technology is the state-of-the-art technology for production of highly concentrated and highly efficient Rosemary and Sage antioxidants and fits especially well into the philosophy of natural antioxidants. Supercritical CO2-extraction of Rosmarinus Officinalis and Salvia Officinalis leaves at a pressure of 500 bar alternatively at lower pressure with a small amount of ethanol as entrainer leads to a primary CO2 extract. This is deodorized very effectively by counter-current CO2-extraction. The refined CO2-extract is highly enriched in the active diterpene phenols (DTPs) mainly carnosic acid, carnosol, rosmanol etc (figure 1). Carnosic acid is the constituent with the highest antioxidative efficacy (5-7). Carnosic acid oxidizes from one antioxidant to another. Acting as a primary antioxidant by donating a hydrogen to quench a free radical, it forms the antioxidant carnosol, which in turn forms another, rosmanol and so on. Carnosic acid thus has primary and secondary antioxidant formation mechanisms, scavenges superoxide radicals (8) and acts as metal chelator (9). In comparison with other extract types the CO2-extract contains the highest concentration of carnosic acid. Flavex offers a complete range of Rosemary and Sage antioxidants for various applications.

Figure 1

Antioxidant Activity
Many methods have been developed and tested for measuring the antioxidant activity. They differ in terms of reaction mechanisms, oxidant and test media, reaction conditions, and expression of results. Even in the case of commercial Rosemary and Sage extracts the large number of literature on the antioxidant activity is difficult to interpret because of the diverse testing systems and applied methods not always reflecting the real oxidation conditions (10).
Two main types of antioxidant activity testing can be distinguished: assays to evaluate radical scavenging activity in model systems; and assays to evaluate oxidation of fats, oils and other fat containing foods. There are various methods available to measure lipid oxidation in foods. Changes in chemical, physical, or organoleptic properties of fats and oils during oxidation can be monitored. When oxidation proceeds, quantification of oxidation artefacts is more appropriate to evaluate product deterioration. Fat stability measuring methods are mostly sample dependent, and the final result usually depends on sample type, amount and surface area. They require long sample storage times, so they are not applicable when results are needed fast. For these purposes model systems like the rancimat method are used, as they provide fast, reproducible and equally informative results. Model systems can be divided into two groups: 1. partially simulating real systems or 2. systems using synthetic reagents that normally do not occur in nature. The first ones mainly use linoleic acid as a substrate, a variety of oxidation acceleration factors and different detection techniques. The second ones mainly employ synthetic stable radicals, such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) [95], or 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). Although these radicals do not exist in nature, it is assumed that compounds able to scavenge these radicals, possess antioxidant activity. All strong natural antioxidants such as carnosic acid reduce DPPH and ABTS radicals (11).

When selecting the most appropriate method, it should be considered that analytical conditions, test media and concentration of antioxidants should simulate real food as much as possible. Antioxidant activity occurs by different mechanisms which means employing a test method depending on one mechanism may not reflect the true antioxidant capacity.
In general the applied methods for measuring the antioxidative activities of the Rosemary components do not reflect the complex antioxidative mechanism of the Rosemary antioxidants in food systems.

Rosemary and Sage Antioxidant Applications
Antioxidant properties of Rosemary have been well documented (8, 9, 12-16). CO2-antioxidants are used in food products containing fats and oils, i.e. meat products, sausages, vegetable oils, marinades, sauces. A very important advantage of the active principles of Rosemary and Sage extracts is their low volatility and following a good "carry-through-effect", which is the ability of ingredients to survive high temperature during food processing.

The above mentioned methods for measuring and evaluating the antioxidant activity require a lot of time and therefore accelerated methods, such as Rancimat is used for assessing the oxidative stability of fats and oils. This is a frequently used method for determining the efficacy of oil-soluble antioxidants.

According to this method lard was stabilized with dl-α-tocopherol, BHT (butylated hydroxytoluene) and increasing amounts of CO2-Rosemary diterpene phenols. All samples were tested by heating to 120 °C and passing through an airflow of 15 l/min in a Rancimat equipment. The protection factor also called activity index of the antioxidant which is defined as the ratio of the induction times with and without antioxidant addition, is plotted against the concentration of diterpene phenols from a CO2-Rosemary extract (figure 2). For comparison purposes the effects of 500 ppm BHT (line 1) and 500 ppm dl-α-tocopherol (line 2) are indicated as well, which clearly shows the superior efficacy of the CO2-Rosemary extract. The dose/activity relation is characterized by a flattening of the curve if more than 200 ppm of Rosemary phenols are applied. The antioxidative efficacy of 200 ppm DTPs from Rosemary antioxidant is superior in comparison to 500 ppm dl-alpha-tocopherol and 500 ppm BHT. Other studies show, that more lipophilic extracts from Rosemary are better antioxidants for lard (17,18) than methanol- or ethanol extracts.

Figure 2. Protection factor Y of CO2-Rosemary diterpene phenols as function of their concentration in lard. 1. Value for 500 ppm BHT, 2. Value for 500 ppm dl-α-tocopherol

Results
Primary and secondary antioxidants are often used in combination in food products for better efficacy.

Rosemary and Sage Antioxidants with their synergistically active compounds acts both as primary and secondary antioxidants and are therefore the perfect all-in-one antioxidants for basic natural food protection.

In food products also possible effects of antagonists must be carefully considered. For example, hemoglobin, myoglobin and chlorophylls may weaken the antioxidant activity due to photosensitized oxidation and the presence of prooxidative transition metal ions like iron and copper and magnesium in chlorophyll. Therefore chelators such as citric acid, ethylenediamintetraacetic acid (EDTA), polyphosphates or their derivatives and Rosemary antioxidant also considered as metal chelator are used extensively in the food industry. For natural food protection lipophilic antioxidants like Rosemary antioxidant and tocopherols are blended with natural emulsifiers like lecithin, which increases dispersability within a multi-phase system, and increase the effectiveness of the formulations.

The synergisms and interactions of the antioxidative components from Rosemary leaves offer flexible and efficient basic food protection. They are effective in low concentrations of 100-500ppm, do only minimally affect aroma, flavor, colour and structure of foods at optimal dosage levels, are stable and resistant to volatilization and last but not least they are all natural and therefore predestined for preserving organic products.

Make Rosemary and Sage CO2-antioxidants your first choice for food and beverage protection.

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