Fast determination of boiling time of yardlong bean using visible and near infrared spectroscopy and chemometrics Original Research Article

The performance of visible and near infrared (Vis–NIR) spectroscopy as a rapid and non-destructive technique to determine the boiling time of yardlong beans was investigated. Vis–NIR spectra of beans boiled for 0, 30 to 300 s were measured. Robust least-squares support vector machines (R-LS-SVM) with RBF kernel obtained the best result. Partial least square based variable elimination (VEPLS) and robust least square-support vector machines based variable elimination (VER-LS-SVM) were used for variable selections. Four most important variables at 409, 614, 880, and 984 nm were selected. After the variable selection, 90% of the variables were eliminated and the model’s residual predictive deviation (RPD) only decreased 10% compared to that of the model without the variable elimination. The results showed that the Vis–NIR spectra can be used to determine the boiling time of yardlong beans during the boiling process.