Quality Control of Beer

In the context of quality control of beer in breweries or in official food control, a range of different analytical methods must be used. The legal parameters of alcohol and original gravity (OG) are usually determined by reference methods such as distillation and pycnometry or by analytical instruments which combine oscillation-type densimetry and refractometry.

In addition to organoleptical and microbiological examination for a standard beer analysis, colour and bitterness are assessed by photometry, organic acids are determined using enzymatic analyses or liquid chromatography, and also higher alcohols using gas chromatography. Therefore, by means of these traditional techniques, beer analysis is both time-consuming and expensive.

Here, a fast routine NMR method is presented using flow injection technology for sample changing. For the first time, NMR and Principal Components Analysis (PCA) have been applied to a collective of 80 beer samples and partial least squares (PLS) regression is used to determine the original gravity of beer from NMR spectra. In addition, quality relevant substances like ethanol and lactic acid were simultaneously quantified. The use of NMR spectroscopy in combination with multivariate statistical techniques is assessed for their use in quality control of beer.