Fundamental study on the impact of silica gel and tannic acid on hordein levels in beer

Demand for gluten-free foods has been increasing and although gluten-free beers are available, the range of styles is limited. In this study beer made from barley malt was treated with either silica gel or tannic acid and compared to unstabilised beer. Hordein levels in the beers were analysed using Western blot and competitive ELISA. Beer quality parameters such as foam, colour and various flavours were also determined. There was no significant impact on beer quality when using silica gel to stabilise the beer and hordein levels were significantly reduced, the highest dose reducing the beer below 4 ppm. Stabilisation with tannic acid reduced the hordein content significantly, the lowest dose reduced hordein to below 21 ppm without significant impact on beer quality. Although beer stabilised with the highest dose of tannic acid had a large reduction in hordein content (< 6 ppm), the quality of the beer was seriously affected. Industrial relevance Existing food stabilisation methods were used to significantly reduce hordein levels in beer. This is an alternative approach for reducing hordein, combining existing technologies making it easy to implement and use in the brewing environment. These stabilisers are readily available from suppliers well known to the food and brewing industry. The global gluten-free market is increasing and these treatments are all widely accepted and commonly used as food processing aids. This hordein reduction strategy could add value to a product at minimal cost increase, and also increase the types of beer available to the gluten-free consumer.