RAPID DETERMINATION OF THE ETHER EXTRACT CONTENT OF MACAUBA PULP USING HANDHELD NEAR-INFRARED (NIR)

The macaúba (Acrocomia aculeata) is a palm tree in the process of domestication present in different regions of the Brazilian territory with significant potential in the bioeconomy, especially in the production of vegetable oil from its fruits. The study of the ether extract content in the mesocarp (pulp) is essential to support breeding programs aimed at commercial exploitation. Near-infrared (NIR) spectroscopy associated with chemometric tools is an effective alternative in the quantification of agro-industrial quality parameters due to its speed and economy of reagents and equipment. In this sense, 60 fruits from 10 different plants cultivated at Embrapa Cerrados (Planaltina/DF) had their spectra collected using a portable NIR (MicroNIR, Viavi), interval of 1676 - 908 nm, acquisition by diffuse reflectance, resolution of 6.2 nm and integration time of 10 ms, and the fruits were divided into calibration (2/3) and validation (1/3). The calibration was developed through the use of partial least squares (PLS) using the Unscrambler X software. The quantification of the ether extract by Ankom (AOCS-Am-5-04) was used as a reference method. The spectra were acquired in triplicate (from three distinct regions) in five pulp slices of each fruit. Two models were constructed using 1) All spectra (15 spectra/fruit); 2) Average spectra per slice (5 spectra/fruit). The coefficient of determination (R2) for calibration was 0.86 and 0.87 and the RMSEC was 3.25 and 3.0% for the models with individual spectra and mean, respectively