Comparative Analysis of Oil Palm Fruit Free Fatty Acid Estimation Using a Portable VIS-NIR Spectrometer and Multispectral Imaging

Abstract The titration method is the conventional approach for measuring free fatty acid (FFA) content in oil palm fruit but is destructive and time-consuming. Since FFA is a critical quality parameter in Indonesia’s palm oil industry, there is an urgent need for rapid, non-destructive alternatives. This study presents a comparative analysis of two non-invasive sensing technologies for estimating oil palm FFA: a portable visible–near infrared (VIS-NIR) spectrometer and a multispectral imaging system. Fruit samples at various maturity stages were analyzed using both methods. The VIS-NIR spectrometer captured spectral reIlectance in the red band (660–670 nm), while the multispectral camera provided corresponding image intensity features. Principal Component Analysis (PCA) of the red band reIlectance showed that PC1 accounted for 98.47% of the variance, clearly separating all ripeness classes. Regression analysis conIirmed strong correlations with FFA content, with the VIS-NIR spectrometer achieving R 2 = 0.85 and multispectral imaging R 2 = 0.79. Expanding the dataset across multiple cultivars and environmental conditions, combined with advanced multivariate modeling, could further improve prediction accuracy. These Iindings demonstrate that both technologies can provide accurate, rapid, and non-destructive estimation of FFA, supporting real-time quality monitoring and improved harvest management in Indonesia’s palm oil sector.