Ripeness and quality of harvested durian determined using Raman spectroscopy combined with physico-chemical and volatile characteristics

The demand for fresh-cut durian tends to increase as customer lifestyles have changed with more demand for convenience in usage and a reduction in the waste generated in the home. This study aimed to find a new sorting method for the ripened durian pulp. Raman spectra from lab-based and portable Raman spectroscopy showed a similar spectra pattern. The important Raman spectra bands for starch were presented on day 1-3 of storage. Bands associated with sugar were observed after day 4, whereas the starch was reduced. Durian pulp compositions during the ripening, especially firmness and weight loss decreased until the end of the storage. Major sulfur-containing compounds such as ethanethiol, diethyl disulfide, diethyl trisulfide and 3,5-dimethyl-1,2,4-trithiolane (isomer I, II) were emitted high amounts on day 4. The principal coordinates analysis (PCoA) and kmeans clustering score plot of Raman spectra allowed the separation of ripeness for whole fruit after harvesting in three distinct stages; unripe stages on day 1-3, the ripen stages on days 4 and 5 and the overripe stages on days 6 and 7. Pearson's correlation coefficient exhibited a closed relationship between the Raman PC scores (106-1800 cm(-1)) and physico-chemical and volatile profile of durian fruit. Raman spectroscopy could be a useful new alternative technique to sort the ripeness and eating quality of durian pulp, substituting for traditional practices in fresh-cut industry.