In commercial olive oil pressing, a key process in food and feed milling,, "Extra Virgin" classification requires a free fatty acidity (FFA) level of less than 0.80% (expressed as oleic acid). Monitoring oil parameters at the decanter and separator outputs allows mills to sort batches immediately and optimize crushing conditions like malaxation times. Traditional FFA values are determined in laboratories via manual titration, requiring chemical reagents and causing significant lag time.
"Flow-through online FT-NIR systems verify decanter output acidity (FFA), moisture, and peroxide levels simultaneously without manual sampling delays."
Analytical Mechanism and Modeling
Olive oil near-infrared spectra reflect carboxylic acid structures (C=O and O-H bonds). Moisture levels show strong absorbance around 1450 nm, while peroxide values (oxidation state indicators) alter specific spectral shoulders. The ProLine17ES Analyzer flow-cell scans oil streams continuously as they flow through output lines.
The caliX platform preprocesses spectra with Standard Normal Variate (SNV) scatter correction and Savitzky-Golay filtering, using PLS regression to predict acidity values. Unit-to-unit optical uniformity ensures models transfer seamlessly across processing lines.
FT-NIR Olive Oil Validation Accuracy
The table below summarizes USTECH online system performance compared to standard reference laboratory methods (AOCS chemical assays):
| Parameter | Reference Method | Calibration Range | FT-NIR Accuracy (RMSEP) | Correlation (R²) |
|---|---|---|---|---|
| Free Fatty Acidity (FFA) | AOCS Ca 5a-40 (Titration) | 0.10 – 3.00% | ≤ 0.05% | 0.989 |
| Peroxide Value (PV) | AOCS Cd 8-53 (Iodometric) | 2 – 30 meq O—/kg | ≤ 1.2 meq/kg | 0.974 |
| Moisture / Volatiles | AOCS Ca 2c-25 (Oven) | 0.05 ≤ 1.00% | ≤ 0.03% | 0.981 |
Key B2B Value Additions
Inline acidity monitoring secures important economic advantages in olive oil facilities:
- Dynamic Batch Routing: Routes high-quality Extra Virgin oil directly to designated tanks, preventing downstream contamination with lower-grade oils.
- Process Optimization: Correlates malaxation temperatures and press times with acidity and oxidation values in real time to sustain premium quality.
- Adulteration Protection: Identifies incoming high-acid or residual oils at raw oil receiving bays instantly.
Conclusion
USTECH Innovations inline spectroscopy solutions help olive oil processors minimize laboratory testing costs, maximize extra virgin yields, and optimize bulk storage tank allocation.
References
- AOCS Official Method Ca 5a-40 - Free Fatty Acids in Crude and Refined Fats and Oils.
- AOCS Official Method Cd 8-53 - Peroxide Value of Fats and Oils.
- "Real-time monitoring of free fatty acidity and peroxide value in olive oil mill decanters using silicon-MEMS FT-NIR spectrometers," Journal of Food Engineering & Chemistry, 2025.
