Non-destructive beer gravity measurement using spectroscopy and machine learning with mRMR-based wavelength selection
摘要
Measuring beer contents, especially initial gravity, is crucial for quality assurance in brewing. This work describes an integrated system to measure beer's original gravity that uses spectroscopy, spectral preprocessing methods, wavelength selection, and sophisticated machine learning (ML) models. Original gravity, which represents the sugar level of the wort prior to fermentation, is directly proportional to the beer's eventual alcohol content. The captured spectral data were preprocessed before being fed into various ML algorithms to estimate beer content. The minimal-redundancy-maximal-relevance (mRMR) technique was used to find the optimal wavelengths, thereby significantly enhancing the precision of the models.
Regression results showed a high coefficient of determination (R2 = 0.998), low root mean square error (RMSE = 0.123), and an excellent ratio of performance to deviation (RPD = 21.75). Leave-One-Out Cross-Validation (LOOCV) confirmed robust performance (R2 = 0.998, RMSE = 0.112). Classification models achieved an average Matthews Correlation Coefficient (MCC) of 95.6% and a Kappa score of 95.2%. These findings indicate that the non-destructive technology, combined with mRMR, provides a dependable and efficient way of determining beer levels.