Near-infrared spectroscopy as a new method for post-harvest monitoring of white truffles

The quality of truffles is related to their maturation stage, and good maturation degree is important in order to have a truffle with valuable organoleptic properties. An innovative, rapid and reliable technique to determine the maturation degree of truffles and monitor their post-harvest ageing process is proposed. Near-infrared (NIR) spectroscopy was used for the first time to monitor the post-harvest ripening of white truffles of two different species (Tuber magnatum and T. borchii). Optical microscopy was flanked by NIR spectroscopy imaging to monitor fruiting bodies at different degrees of maturation. The NIR profile of truffles provided statistical differentiation between the biochemical composition of different tissues (vegetative hyphae and ascospores). The optical evaluation of the degree of maturation was correlated to spectral information in order to obtain a non-operator dependent, rapid, simple and cost-effective method to evaluate the degree of maturation of white truffles. Partial least square regression (PLS) was used for multivariate calibration of NIR spectra against maturation degree, and ripening curves were obtained (with correlation coefficients R-2 = 0.95 for T. magnatum and R-2 = 0.76 for T. borchii). Moreover, a classification method based on PLS discriminant analysis of truffle in three maturity stages was developed, achieving a total of correct classification rate of 83%.