Changes in quality and composition of volatile compounds of saffron affected by storage time in two consecutive years

Modifications in saffron quality characteristics due to storage time between samples harvested from two consecutive years have not been studied well. For this purpose, saffron samples harvested from 2016 and 2017 were analyzed using proton transfer reaction-time of flight-mass spectrometry (PTR-TOF-MS) and ISO 3632 trade standard procedures to determine volatile compounds as well as crocin and picrocrocin contents, respectively. The results of volatile organic compounds (VOCs) analysis revealed that 11 main compounds including safranal, acetic acid, 2(5H)-furanone, isobutanal, biogenic aldehyde fragment, 4-ketoisophorone, acetaldehyde, butyrolactone, acetone/propanal, methanol, and isophorone were responsible for the overall VOCs profile of saffron, as accounted for more than 80% of the identified VOCs. Comparisons between samples stored from two years showed that safranal, acetic acid, 2(5H)-furanone, biogenic aldehyde fragment, and butyrolactone compounds were significantly increased for samples stored from 2016 (between 56-82 percent) compared with the samples obtained from 2017. On the contrary, isophorone isomers contents as safranal precursors, decreased their contents relatively. Similarly, crocin and picrocrocin contents measured by ISO method differed significantly between samples of two studied years. For all the studied samples, color and flavor factors of saffron reduced by 20 and 14% on the average for  samples stored from 2016 in comparison with amples obtained from 2017, respectively. According to results of principal component analysis, change in crocin, picrocrocin, and main volatile compounds of saffron including safranal, acetic acid, 2(5H)-furanone, isobutanal, and isophorone could be considered as an indicator for distinguishing the current year’s harvested samples from the samples stored since previous years.