Bibliographic Details
| Title: |
Determination of Sugars and Acids in Grape Must Using Miniaturized Near-Infrared Spectroscopy |
| Authors: |
Lucie Cornehl, Julius Krause, Xiaorong Zheng, Pascal Gauweiler, Florian Schwander, Reinhard Töpfer, Robin Gruna, Anna Kicherer |
| Source: |
Sensors, Vol 23, Iss 11, p 5287 (2023) |
| Publisher Information: |
MDPI AG, 2023. |
| Publication Year: |
2023 |
| Collection: |
LCC:Chemical technology |
| Subject Terms: |
grapevine, NIRS, quality, ripening, harvest, precision viticulture, Chemical technology, TP1-1185 |
| More Details: |
An automatic determination of grape must ingredients during the harvesting process would support cellar logistics and enables an early termination of the harvest if quality parameters are not met. One of the most important quality-determining characteristics of grape must is its sugar and acid content. Among others, the sugars in particular determine the quality of the must and wine. Chiefly in wine cooperatives, in which a third of all German winegrowers are organized, these quality characteristics serve as the basis for payment. They are acquired upon delivery at the cellar of the cooperative or the winery and result in the acceptance or rejection of grapes and must. The whole process is very time-consuming and expensive, and sometimes grapes that do not meet the quality requirements for sweetness, acidity, or healthiness are destroyed or not used at all, which leads to economic loss. Near-infrared spectroscopy is now a widely used technique to detect a wide variety of ingredients in biological samples. In this study, a miniaturized semi-automated prototype apparatus with a near-infrared sensor and a flow cell was used to acquire spectra (1100 nm to 1350 nm) of grape must at defined temperatures. Data of must samples from four different red and white Vitis vinifera (L.) varieties were recorded throughout the whole growing season of 2021 in Rhineland Palatinate, Germany. Each sample consisted of 100 randomly sampled berries from the entire vineyard. The contents of the main sugars (glucose and fructose) and acids (malic acid and tartaric acid) were determined with high-performance liquid chromatography. Chemometric methods, using partial least-square regression and leave-one-out cross-validation, provided good estimates of both sugars (RMSEP = 6.06 g/L, R2 = 89.26%), as well as malic acid (RMSEP = 1.22 g/L, R2 = 91.10%). The coefficient of determination (R2) was comparable for glucose and fructose with 89.45% compared to 89.08%, respectively. Although tartaric acid was predictable for only two of the four varieties using near-infrared spectroscopy, calibration and validation for malic acid were accurate for all varieties in an equal extent like the sugars. These high prediction accuracies for the main quality determining grape must ingredients using this miniaturized prototype apparatus might enable an installation on a grape harvester in the future. |
| Document Type: |
article |
| File Description: |
electronic resource |
| Language: |
English |
| ISSN: |
1424-8220 |
| Relation: |
https://www.mdpi.com/1424-8220/23/11/5287; https://doaj.org/toc/1424-8220 |
| DOI: |
10.3390/s23115287 |
| Access URL: |
https://doaj.org/article/18fb3bbc91194b9cbea125005e0c5e63 |
| Accession Number: |
edsdoj.18fb3bbc91194b9cbea125005e0c5e63 |
| Database: |
Directory of Open Access Journals |
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