Original article Rapid determination of oil content in dried-ground oil palm mesocarp and kernel using near infrared spectroscopy Sudarno 1 , Divo D Silalahi 1 , Tauvik Risman 1 , Baiq L Widyastuti 1 , F Davrieux 2 , Yong Yit Yuan 1 and Jean P Caliman 1 Abstract Nearinfrared spectroscopy calibrations for rapid oil content determination of dried-ground oil palm mesocarp and kernel were developed. Samples were analyzed, one set using the Soxhlet extraction method for reference analysis and the other set scanned by near infrared spectroscopy instrument for calibration. Successful calibrations were obtained with good accuracy and precision for mesocarp and kernel, based on statistical models. Math treatment and scatter correction had significant effects on the fitting of the calibration model. The best obtained calibration models were demonstrated by multiple correlation coefficient (R 2 ), standard error of calibration, standard error of cross validation, coefficient of deter- mination in cross validation (1-VR) and relative predictive deviation of calibration, which respectively were 0.997, 1.21%, 1.23%, 0.997 and 17.89 for mesocarp and 0.952, 0.47%, 0.53%, 0.94 and 4.00 for kernel. The correlations between reference and predicted values for samples in the validation sets were in agreement with high linearity, high ratio performance to deviation of prediction (4.00) and low standard error of prediction samples for both samples. The results demonstrated that near infrared spectroscopy can be used as an alternative and reliable technique to estimate the mesocarp and kernel oil contents in dry matter basis accurately and rapidly. Keywords Oil content, mesocarp, kernel, oil palm fruits, near infrared spectroscopy Received 5 December 2016; accepted 30 August 2017 Introduction Oil palm (Elaeis guineensis Jacq.) is one of the most important agricultural crops, as the major source of vegetable oil production in the world. Palm oil can be used for various edible and non-edible products such as cooking oil, margarine, ice cream and cocoa butter substitutes, soap and oleo-chemical products 1–3 and renewable fuels as well. 4 In order to sustain the global supply of palm oil, research and development aimed at increasing the oil productivity is of utmost importance, especially for breeding oil palm planting material with high oil content. Bunch analysis using the method developed by Blaak et al. is used for studying the bunch and fruit traits of oil palm trees. 5 Modification of the method had been suggested by Rao et al. 6 and this had been widely applied by plant breeders till now. 7 One of the procedural steps of the bunch analysis is oil content determination of oil palm mesocarp (MS) and kernel (KN) conducted in laboratory. Rapid determin- ation of oil content in oil palm fruit is critical for assess- ing and monitoring the productive potential of oil palm trees in breeding trials that generate a large number of samples. The conventional method for determining oil con- tent in oil palm mesocarp and kernel is Soxhlet extrac- tion using n-hexane as a solvent. This method is time consuming, hazardous and highly toxic because n-hexane is used. These drawbacks have resulted in interest to develop an alternative method for the oil content determination that has superiorities compared to the conventional one. Recently, two technological applications were employed for oil content determin- ation, namely nuclear magnetic resonance (NMR) and near infrared (NIR) spectroscopy techniques. 1 SMART Research Institute (SMARTRI), Riau, Indonesia 2 CIRAD, Performance of Tropical Production and Processing Systems Department, UMR QUALISUD, Montpellier Cedex 5, France Corresponding author: Sudarno, SMART Research Institute (SMARTRI), PT SMART Tbk, Riau, Jl. Teuku Umar 19, Pekanbaru 28112 Riau, Indonesia. Email: darno_scicat@yahoo.com Journal of Near Infrared Spectroscopy 2017, Vol. 25(5) 338–347 ! The Author(s) 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0967033517732679 journals.sagepub.com/home/jns