Performance comparison of calibrated fourier transformation infrared spectroscopy (FTIR) and automated beer analyzer in quality control studies

Fourier transformation infrared spectroscopy (FTIR) as to its potential in quantifying beer parameters was investigated, aiming to figure out the feasibility for its application in practice compared to a commonly used automated beer analyzer. For this purpose, a FTIR system including a database was set up and calibrated for the most important beer parameters, such as original wort, pH, alcohol content, specific gravity, extract (real and apparent), fermentation, caloric value, and refraction index. A set of in total 329 beers marketed in Europe was analyzed with an FTIR system and a commercially available automated beer analyzer. A statistical evaluation revealed no significant differences of the analytical performance of both systems. Highest correlation coefficients R² (close to 1) were found for all parameters, except for the pH (0.901). A certain limit was observed in analyzing the pH parameter via FTIR, but was still sufficient for a precise quantification. The analysis of the parameters via FTIR remained stable over a period of 80 days. The use of antifoaming agents affected the FTIR spectra and, therefore, cannot be recommended. When testing the FTIR system in interlaboratory studies, a standardized sample preparation is highly recommended to obtain reproducible spectra. The results concluded that a well calibrated FTIR system can replace less practicable automated beer analyzers in quantifying quality relevant beer ingredients.