Chemical Changes in the Broccoli Volatilome Depending on the Tissue Treatment

The storage of plant sample as well as sample preparation for extraction have a significant impact on the profile of metabolites. However, this parameter is often overlooked during experiments on plants. It was hypothesised that parameters such as sample storage (freezing) and sample pre-treatment methods, including the comminution technique or applied enzyme inhibition methods could significantly influence the extracted volatile metabolome.Significant changes were observed in the volatile profile of broccoli florets frozen in liquid nitrogen and at -20 o C. Those differences were mostly related to the concentration of nitriles and aldehydes. Confocal microscopy indicated some tissue deterioration in the case of slow freezing (-20 o C), whereas the structure of tissue, frozen in liquid nitrogen, was practically intact. Myrosinase activity assay proved that the enzyme remains active after freezing. No pH deviation was noted after sample storage - this parameter did not influence the activity of enzymes. Tissue fragmentation and enzyme-inhibition techniques applied prior to the extraction influenced both qualitative and quantitative composition of the volatile metabolome of broccoli.