Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms

In the following study, total sugar concentrations before and during alcoholic fermentation, as well as ethanol concentrations and pH levels after fermentation, of red and white wine grapes were successfully predicted using Raman spectroscopy. Fluorescing compounds such as anthocyanins and pigmented...

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Main Authors: Harrison Fuller, Chris Beaver, James Harbertson
Format: Article
Language:English
Published: MDPI AG 2021-12-01
Series:Beverages
Subjects:
Online Access:https://www.mdpi.com/2306-5710/7/4/78
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author Harrison Fuller
Chris Beaver
James Harbertson
author_facet Harrison Fuller
Chris Beaver
James Harbertson
author_sort Harrison Fuller
collection DOAJ
description In the following study, total sugar concentrations before and during alcoholic fermentation, as well as ethanol concentrations and pH levels after fermentation, of red and white wine grapes were successfully predicted using Raman spectroscopy. Fluorescing compounds such as anthocyanins and pigmented phenolics found in red wine present one of the primary limitations of enological analysis using Raman spectroscopy. Unlike the spontaneous Raman effect, fluorescence is a highly efficient process and consequently emits a much stronger signal than spontaneous Raman scattering. For this reason, many enological applications of Raman spectroscopy are impractical as the more subtle Raman spectrum of any red wine sample is in large part masked by fluorescing compounds present in the wine. This work employs a simple extraction method to mitigate fluorescence in finished red wines. Ethanol and total sugars (fructose plus glucose) of wines made from red (Cabernet Sauvignon) and white (Chardonnay, Sauvignon Blanc, and Gruner Veltliner) varieties were modeled using support vector regression (SVR), partial least squares regression (PLSR) and Ridge regression (RR). The results, which compared the predicted to measured total sugar concentrations before and during fermentation, were excellent (R<sup>2</sup><sub>SVR</sub> = 0.96, R<sup>2</sup><sub>PLSR</sub> = 0.95, R<sup>2</sup><sub>RR</sub> = 0.95, RMSESVR = 1.59, RMSEPLSR = 1.57, RMSERR = 1.57), as were the ethanol and pH predictions for finished wines after phenolic stripping with polyvinylpolypyrrolidone (R<sup>2</sup><sub>SVR</sub> = 0.98, R<sup>2</sup><sub>PLSR</sub> = 0.99, R<sup>2</sup><sub>RR</sub> = 0.99, RMSESVR = 0.23, RMSEPLSR = 0.21, RMSERR = 0.23). The results suggest that Raman spectroscopy is a viable tool for rapid and trustworthy fermentation monitoring.
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spelling doaj.art-7ba5e66dfe844f0ebc7e917e568de1392023-11-23T03:51:55ZengMDPI AGBeverages2306-57102021-12-01747810.3390/beverages7040078Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning AlgorithmsHarrison Fuller0Chris Beaver1James Harbertson2St Michelle Wine Estates WSU Wine Science Center, School of Food Science, College of Agricultural, Human, and Natural Resource Sciences, Washington State University, 359 University Drive, Richland, WA 99354, USASt Michelle Wine Estates WSU Wine Science Center, School of Food Science, College of Agricultural, Human, and Natural Resource Sciences, Washington State University, 359 University Drive, Richland, WA 99354, USASt Michelle Wine Estates WSU Wine Science Center, School of Food Science, College of Agricultural, Human, and Natural Resource Sciences, Washington State University, 359 University Drive, Richland, WA 99354, USAIn the following study, total sugar concentrations before and during alcoholic fermentation, as well as ethanol concentrations and pH levels after fermentation, of red and white wine grapes were successfully predicted using Raman spectroscopy. Fluorescing compounds such as anthocyanins and pigmented phenolics found in red wine present one of the primary limitations of enological analysis using Raman spectroscopy. Unlike the spontaneous Raman effect, fluorescence is a highly efficient process and consequently emits a much stronger signal than spontaneous Raman scattering. For this reason, many enological applications of Raman spectroscopy are impractical as the more subtle Raman spectrum of any red wine sample is in large part masked by fluorescing compounds present in the wine. This work employs a simple extraction method to mitigate fluorescence in finished red wines. Ethanol and total sugars (fructose plus glucose) of wines made from red (Cabernet Sauvignon) and white (Chardonnay, Sauvignon Blanc, and Gruner Veltliner) varieties were modeled using support vector regression (SVR), partial least squares regression (PLSR) and Ridge regression (RR). The results, which compared the predicted to measured total sugar concentrations before and during fermentation, were excellent (R<sup>2</sup><sub>SVR</sub> = 0.96, R<sup>2</sup><sub>PLSR</sub> = 0.95, R<sup>2</sup><sub>RR</sub> = 0.95, RMSESVR = 1.59, RMSEPLSR = 1.57, RMSERR = 1.57), as were the ethanol and pH predictions for finished wines after phenolic stripping with polyvinylpolypyrrolidone (R<sup>2</sup><sub>SVR</sub> = 0.98, R<sup>2</sup><sub>PLSR</sub> = 0.99, R<sup>2</sup><sub>RR</sub> = 0.99, RMSESVR = 0.23, RMSEPLSR = 0.21, RMSERR = 0.23). The results suggest that Raman spectroscopy is a viable tool for rapid and trustworthy fermentation monitoring.https://www.mdpi.com/2306-5710/7/4/78Raman spectroscopypredictive modelingmachine learningregressionenologywinemaking
spellingShingle Harrison Fuller
Chris Beaver
James Harbertson
Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
Beverages
Raman spectroscopy
predictive modeling
machine learning
regression
enology
winemaking
title Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
title_full Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
title_fullStr Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
title_full_unstemmed Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
title_short Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms
title_sort alcoholic fermentation monitoring and ph prediction in red and white wine by combining spontaneous raman spectroscopy and machine learning algorithms
topic Raman spectroscopy
predictive modeling
machine learning
regression
enology
winemaking
url https://www.mdpi.com/2306-5710/7/4/78
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