Chemists have designed a polymer that can improve the shelf life of drinks, such as beer.

Riboflavin degrades in light, affecting the taste of drinks

One of the long standing problems in the drinks industry is how to prevent chemical processes in the drinks compromising their taste, quality and shelf life. In particular, riboflavin (vitamin B2) is responsible for driving photooxidation reactions that affect the flavour of many drinks and so they often have to be packaged in light-shielded containers.

Now Börje Sellergren, at the Technical University of Dortmund, Germany, and colleagues have developed a way of removing riboflavin. They imprinted riboflavin-shaped pockets into a polymer by synthesising it in the presence of riboflavin tetra-acetate template molecules. Removing the template left empty receptor pockets, which the team showed could capture and remove riboflavin from milk, beer and multivitamin mixtures.

According to Sellergren, his molecularly imprinted polymer is unlike many others designed to capture or detect small molecule targets because it performs well in aqueous systems. It can extract up to 86 per cent of the riboflavin compared to 47 per cent for the corresponding non-imprinted control polymer, he explains. 'Food analysis and processing is a field that would profit from such receptors,' he says. 'Generic techniques to prepare fully water-compatible molecularly imprinted polymers will become important for unlocking such applications.'

Nicholas Snow, who specialises in separation science at Seton Hall University, South Orange, US, says the work represents 'an important transition [for molecularly imprinted polymers] from being artificial receptors used in laboratory applications to being scrubbers capable of selectively removing unwanted, toxic or irritating compounds from many types of consumer products'.

Antonio Martín-Esteban an expert in analytical applications of molecularly imprinted polymers at the National Institute for Agriculture and Food Research and Technology, Madrid, Spain, comments that Sellergren's polymer formation strategy 'is so simple and effective that it will most likely become routinely incorporated in the synthesis of a new generation of improved water-compatible imprinted polymers'.

A significant proportion of the riboflavin is still removed by non-specific hydrophobic binding interactions, says Sellergren. The next step is to refine further the polymer preparation process to reduce the non-specific binding, while retaining the integrity and activity of the specific binding pockets.

David Parker

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