Evaluation of sugar content in hopped wort of artisanal beer by shortwave infrared spectroscopy

In brewing business more and more consistent quality, coupled with innovation and production cost reduction, is required. One of the most important parameters to be monitored during fermentation is density, being directly correlated with the alcohol and sugar content. The traditional method used to measure beer density requires the utilization of a hydrometer. In this study, a simple and fast approach to assess sugar content in hopped wort of artisanal beer, based on the utilization of a portable spectroscopic device working in the Short-Wave InfraRed (SWIR) region (1000-2400 nm), is adopted in order to be utilized both off- and on-line. The proposed approach, faster than the traditional hydrometric method, will allow to realize a better control of the process, reducing production cost and increasing, at the same time, product quality. Starting from the collected spectra, acquired in transreflectance mode and the reference density data, Partial Least Square (PLS) regression models able to predict the density of hopped wort were developed (i.e., Rp 2=0.98 and RMSEP = 0.3 °P; Rp 2=0.97 and RMSEP=0.5 °P, after VIP scores selection). PLS regression was optimized by pre–processing algorithms using an ad hoc code to achieve optimal performances and the computational time was reduced performing a wavelength reduction by VIP scores method.