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Ethanol content in wine by near-infrared spectroscopy

AN-NIR-147

2025-12

pt_PT

Rapid determination of alcohol levels in wine with NIRS

Ethanol content can be quickly and easily determined in different wines during fermentation and afterwards for quality control using near-infrared spectroscopy.

Ethanol content is an important parameter to determine in wine—during the fermentation process, for quality control, and for other legal requirements of alcoholic beverages. Traditional time-consuming methods like gas chromatography (GC) can be used for the determination of ethanol content in wine. However, measuring the alcohol content in wine can be done easily without sample preparation by using near-infrared spectroscopy (NIRS).

NIRS is a fast, easy to use, and chemical-free analysis method. The NIRS solution can be used either atline during the wine fermentation process or in a quality control laboratory.

 

Figure 1. OMNIS NIR Analyzer Liquid and OMNIS Sample Robot S – WSM (1T/2P).

Samples of red wine and white wine with varying alcohol content were measured on an OMNIS NIR Analyzer Liquid (1000–2250 nm). Measurements were performed in transmission mode with a 2 mm flow-through cell and corresponding holder for flow-through cells. The built-in peristaltic pump on the OMNIS Sample Robot S was used for liquid transfer (Figure 1). OMNIS Software was used for all data acquisition and prediction model development.

Table 1. Hardware and software equipment overview.
Equipment Article number
OMNIS NIR Analyzer Liquid 2.1070.0010
NIRS 12.5 mm quartz cuvette flow 2 mm 6.7401.320
Holder OMNIS NIR, flow-through cells 6.07401.100
OMNIS Stand-Alone license 6.06003.010
OMNIS Stand-Alone: 1 instrument license 6.06002.010
Software license Quant Development 6.06008.002
OMNIS Sample Robot S – WSM (1T/2P) 2.1010.1120
OMNIS Sample rack, 25 x 75 mL (PP) 6.02041.040
Gripper fingers 28-48 mm 6.02601.040

The obtained NIR spectra of wine (Figure 2) were used to create a prediction model for ethanol content. A leave one out validation procedure was applied. A correlation diagram showing the relation between the NIR prediction and the reference values is shown in Figure 3 together with the respective figures of merit (FOM).

Figure 2. NIR spectra of different wine samples measured on an OMNIS NIR Analyzer Liquid with a 2 mm flow-through cell.

Result ethanol content in wine

Figure 3. Correlation diagram and the respective figures of merit for the prediction of ethanol in wine. The determination of ethanol content in wine using gas chromatography was performed for reference values.
R2 SEC (% vol) SECV (% vol)
0.995 0.080 0.082

This Application Note shows the feasibility of using NIR spectroscopy for testing ethanol content in wine. The analysis can be conducted within seconds. No chemicals are used, saving costs. Automation possibilities with the OMNIS platform allow the unattended measurement of up to 175 samples. 

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