Assessment of a portable near-infrared spectral sensor for enhancing virgin olive oil quality control

Ensuring the quality and authenticity of olive oils is a significant challenge for the industry, as current analytical methods rely on expensive equipment, trained personnel, and long-duration processes. To address this issue, the implementation of Near Infrared Spectroscopy (NIRS) - a rapid, cost-effective, multiparameter, and non-invasive analytical technology, might be considered. The aim of this research was to optimize key NIRS methodological aspects, such as sample presentation and spectral data acquisition, to enhance the effectiveness of a portable near infrared device based on Linear Variable Filters (LVF) in real-world conditions, for on-site olive oil quality assessments. Additionally, the performance of the LVF sensor was compared with that of a benchtop instrument using in both cases 810 olive oil samples. The results obtained showed that the transmission module used with 10 mm optical path-length polystyrene cuvettes was the best accessory for on-site analysis of olive oil with the LVF instrument. Despite differences in spectral range, resolution, and operational settings, the portable device demonstrated strong predictive capabilities for key quality parameters, such as Acidity and Fatty acid ethyl esters (residual predictive deviation for cross-validation (RPD_cv) values of 5.67; 2.07, respectively), achieving results comparable to those of the laboratory instrument (RPD_cv = 8.45; 2.07, respectively). This marks a significant advancement in NIRS application in the olive oil industry, offering portable and accessible solutions to enhance quality control and traceability, improve transparency, and reduce fraud. The study provides a novel and practical framework for the implementation of portable NIRS sensors, contributing both to academic progress in methodological standardization and to the development of low-cost analytical tools for a sector characterised by a highly fragmented production landscape, where small producers often lack access to expensive laboratory equipment.