Evaluation of maturity of durian and its eating quality by near infrared spectroscopy technique
Near infrared spectroscopy was used as a non-invasive technique for the evaluation of eating quality (Texture, Dry matter and Soluble solids) of durian. A set of 25 fruits was randomly scanned on tree at the cheek of the biggest locule of each fruit for spectral data using visible and NIR short wavelength diode array spectrometer (FQA-NIR GUN Fantec, Japan) and longwave linear variable filters near infrared spectrometer (MicroNIR, JDSU, USA), every 10 days starting from 80 days until 127 days after fruit onset development covering six levels of maturity (80, 90, 100, 110, 120 and 127 days). After applying ethephon on the fruit stems, the fruits were kept for 3 days at room temperature and allowed to ripen. The laboratory experiment was performed at room temperature (26±2 °C). Fourier transform near infrared (FT-NIR), FQA-NIR GUN and MicroNIR spectrometers were used to scan the spectrum at the cheek of the biggest locule of fruit, the bottom of fruit, the durian pulp and the plastic wrap-covered pulp. Then, the texture, dry matter and soluble solids values were immediately determined by their standard methods. The optimum models were obtained from dry matter determination scanning at the durian pulp and the plastic wrap-covered pulp by FT-NIR spectrometer. It showed the coefficient of determination (r2) and root mean square error of prediction (RMSEP) of 0.89 and 3.60%, 0.83 and 4.60%, respectively. In addition, the models were used to predict 120 unknown durian samples showing the r2 of 0.88 and 0.85 for the durian pulp and the plastic wrap-covered pulp, respectively.