Metabolic Changes during Sprouting of Rapeseed and Their Consequences for the Volatilome of Cold‐Pressed Oil

All the procedures before pressing seeds have a great influence on the flavor of cold-pressed rapeseed oil. However, the studies on the modification of aroma caused by inappropriate storage leading to sprouting are scarce. Therefore, this study aims to determine the effects of sprouting on the metabolome and volatilome of rapeseed cold-pressed oil and press cakes. The presence of 56 and 21 nonvolatile metabolites is detected in seeds/press cakes and oil, respectively. Sprouting significantly affects the total contents of all groups of compounds, except sugars. At the same time, 375 volatile organic compounds (VOCs) are detected. The abundance of VOCs in sprouted oil is almost threefold higher compared to control oil, with the biggest contribution of sulfur-containing compounds (dimethyl sulfide), glucosinolate derivatives (4-isothiocyanato-1-butene), and aldehydes (3-methylbutanal). A similar tendency is observed in press cake. Moreover, sprouting results in the biggest number of VOCs detected only in this oil (61). The abundance of aroma-active compounds is much higher in sprouted products compared to corresponding controls, which has a confirmation in sensory analysis. This study shows that simultaneous volatilomics and metabolomics can be used to track the changes in the oil quality caused by the inappropriate storage of seeds. Sprouting leads to metabolic changes in seeds, which intensify the formation of new VOCs and consequently aroma of oils.
Practical applications: The results of this study will help to understand the formation of volatile organic compounds (VOCs) during the processing and production of cold-pressed rapeseed oil. The combination of VOCs with nonvolatile precursors can help to understand the pathways involved in VOCs formation. Moreover, the oil obtained from sprouted seeds is characterized by many VOCs not present in control oil, which can potentially be used to develop tools for quick evaluation if the seeds used for pressing initiated sprouting, which can lead to changes in its sensory quality.