Exploring Freshness Markers of Postharvest Spinach by Volatile Emission Profiling

Abstract

A gas chromatography-mass spectrometry (GC-MS) based metabolomics approach was used to identify specific volatile compounds as an indicator for assessing the freshness degree of harvested spinach leaves during storage. Volatiles produced from the leaves stored at 5 °C, 15 °C, and 25 °Cwere collected periodically in a gas adsorption tube and subsequently withdrawn into GC-MS by a thermal desorption method. Partial least squares regression for predicting the cumulative storage temperature based on the detected volatiles has selected ten substances as important volatiles that can explain the degrees of freshness, which belong to terpene, alcohol, aldehyde, hydrocarbon, and unknown ones. A hierarchical cluster analysis revealed that the composition ratios of these compounds allowed estimating the cumulative storage temperature of the samples in three levels. These results suggest that the profiling of volatile compounds emitted from stored spinach could probably be a practical method for assessing the degrees of freshness.