The dilemma of rosemary antioxidant E392

By Dr Karl-Werner Quirin

Rosemary antioxidants are derived from the needle like leaves of Rosmarinus officinalis, which are an integral part of the Mediterranean diet. They contain different compounds with antioxidative property, especially phenolic diterpenes. Rosemary antioxidants have recently been classified as food additive and assigned the number E392. The new status applies if added to foods and supplements with technological function as antioxidant also if this intention is combined with other nutritional or flavouring purposes.

An advantage is that the approval is based on the EFSA safety assessment stating that tox-data are insufficient to establish a numerical ADI but that the margin of safety is high enough for use as antioxidative food ingredient.

The new classification is however also connected to obligations. The latest amendment of Directive 2008/84/EC on specific purity criteria of food additives other than colours and sweeteners provides in Annex I the definition and specifications for rosemary antioxidants. Reference antioxidative compounds are carnosic acid and carnosol, which should not represent less than 90 percent of the total diterpene phenols. Borneol, bornyl acetate, camphor, 1,8-cineol and verbenon are considered as reference volatiles.

Depending on production processes by using normal solvents like ethanol, acetone and hexane or supercritical carbon dioxide the content of reference antioxidant compounds, the antioxidant/volatiles ratios as well as the residual solvent contents are specified for different types of rosemary antioxidants. A max amount of 3 mg/kg arsenic and of 2 mg/kg lead applies in all cases.

Besides the obligations of the producer there are obligations of the user according to Directive 95/2/EC, Annex III, Part D referring to the declaration as "Antioxidant: E392" alternatively as "Antioxidant: Rosemary extract". In addition upper limits of use are defined expressed as sum of carnosic acid + carnosol for different groups of food, e.g. 30 ppm in vegetable oils for non heat treated products; 50 ppm in fats and oils for heat treated food, frying oil, fish and algal oils; 100 ppm (on fat basis) in sauces; 200 ppm (on fat basis) in bakeries, in dehydrated potatoes and egg products up to 400 ppm in supplements and 1000 ppm in flavourings.

Here it has to be criticised that the approved addition to different types of oils which represents one of the main applications of antioxidants is in principle too low in order to provide adequate protection. Rosemary antioxidants which were not regulated and limited before and therefore considered as ultra natural are even more restricted than gallates (E310 - E312), TBHQ (E319), BHA (E320) and BHT (E321). For example in fats and oils for heat treated food rosemary is limited to 50 ppm whereas accumulated gallates, TBHQ and BHA are allowed up to 200 ppm. In frying oil and fat rosemary is restricted to 50 ppm, BHT to 100 ppm; in chewing gum rosemary is allowed up to 200 ppm, gallates, TBHQ and BHA in total up to 400 ppm.

The discrimination of rosemary antioxidants is still more evident if compared to tocopherols (E306 - E309), which are approved in general at quantum satis in accordance with good manufacturing practice apart from some infant formulae. The reason for this situation might be that mixed tocopherols were authorised back in 1989 by former SCF. Even a quiet high NOAEL value of 300 mg alpha-tocopherol equivalence per day was allocated (SCF, 2003), a fact which is differently judged today since tocopherols have besides their radical scavenging property also prooxidative potential if applied in higher dosage. For comparison rosemary is limited to 400 ppm antioxidative compounds in supplements and taking six pills or capsules a day of 0.5 g means an amount of 1.2 mg antioxidants which is 250 times lower than the tocopherol value. In order to be fair the very conservative values for rosemary antioxidants are certainly due to the fact that there are not enough tox data available according to present standards which does however not mean that rosemary antioxidants are more harmful than other products.

Biography

Dr Karl-Werner Quirin is a chemist and received his PhD in 1984 from the University of Saarland, Institute of Pharmacognosy and Analytical Phytochemistry. For 24 years he has worked as CEO of FLAVEX Naturextrakte GmbH, a company producing specialty botanical extracts for cosmetics, food and dietary supplements on the base of supercritical CO2-extraction.