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Methods for tartaric acid and tartrates permitted in food consumed in the UK

Project Code: A01035

30/11/2004

LGC
Lawrance, P

Tartaric acid (E334) and its salts (E335-337, E354) are generally permitted additives controlled by the Miscellaneous Food Additives Regulations 1995 (as amended) [1]. These additives are used in food as a source of acidity and also as buffers and taste modifiers.

To fulfil EU requirements for the monitoring of food additives, robust, validated methods are required for those foods in which the use of tartrates is permitted by the regulations. Currently, methods are only available for wines, cheese and fruit and few, if any methods exist for other foods. Therefore there is a need to further develop and validate methods for tartaric acid and its salts in a variety of foodstuffs.

The remainder of the project was focussed on developing an appropriate extraction and clean-up protocol to extend the scope of the published procedures to a wider range of foods.

Test samples containing known amounts of tartaric acid were prepared. These were lemonade, sugar syrup, jam, cocoa powder, Madeira cake and Digestive biscuit. These foods were fortified with tartaric acid to reflect the levels of normal use.

Extraction protocols and clean-up procedures were investigated, developed and applied to each food type. A protocol was developed that was capable of extracting and quantifying tartrates in all of the foods. This protocol involved aqueous extraction with a neutral buffer followed by ion exchange, solid phase extraction to remove interfering components. Extracts were then analysed using HPLC with UV detection. The protocol was validated in-house.

An additional validation exercise was conducted in a second laboratory . The results from the external validation had acceptable precision but the recoveries were low compared to the originating laboratory results obtained at the same time. Discussions between the two laboratories have been unable to identify the cause of this variation. Further evaluation of method robustness is required.

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