A low-cost prototype for monitoring the fermentation of must: initial laboratory-scale tests

A relevant aspect of modern viticulture and the wine-making process is to ensure a good quality control by a correct handling of the alcoholic fermentation. Currently, there are systems available on the market that can assist the winemaker in feeding the yeast during the fermentation process according to predetermined nutrient profiles. To optimise this operation and improve nutrient dosing, an objective evaluation of quality parameters related to the various phases of the fermentation process (i.e., TSS, density and developed alcohol) is required. In this context, this work aims to design, build, and test a monitoring system using optical Vis/NIR sensors. A first prototype version was developed and used for laboratory-scale measurements to evaluate a simulated red grape fermentation process. The module was designed and built using 3D resin printers. It was equipped with a halogen lamp (20W, 12V, MR11) and a cooling system controlled by a microcontroller (Arduino Nano). Spectral measurements were performed using two ultra-compact spectrometric heads that detect optical signals from 340 nm to 850 nm (Hamamatsu, C12880MA) and from 640 nm to 1050 nm (Hamamatsu, C14384MA-01), respectively. The result showed a good predictive performance (evaluated in cross-validation) with an RPD equal to 8.9. This sensing architecture will be combined and/or used in cooperation with chemical/physical sensors (temperature, pressure, CO2, etc.) to develop a real-time multi-parameter system to be used as a PAT in yeast feeding machines to develop a quality-by-design approach for oenology 4.0.