The glucosinolates and their bioactive derivatives in Brassica: a review on classification, biosynthesis and content in plant tissues, fate during and after processing, effect on the human organism and interaction with the gut microbiota.

The present study is a systematic review of the scientific literature reporting content, composition and biosynthesis of glucosinolates (GLS), and their derivative compounds in Brassica family. An amended classification of brassica species, varieties and their GLS content, organized for the different plant organs and in uniformed concentration measure unit, is here reported for the first time in a harmonized and comparative manner. In the last years, the studies carried out on the effect of processing on vegetables and the potential benefits for human health has increased rapidly and consistently the knowledge on the topic. Therefore, there was the need for an updated revision of the scientific literature of pre- and post-harvest modifications of GLS content, along with the role of gut microbiota in influencing their bioavailability once they are ingested. After analyzing and standardizing over 100 articles and the related data, the highest GLS content in Brassica, was declared in B. nigra (L.) W. D. J. Koch (201.95 ± 53.36 µmol g-1), followed by B. oleracea Alboglabra group (180.9 ± 70.3 µmol g-1). The authors also conclude that food processing can influence significantly the final content of GLS, considering the most popular methods: boiling, blanching, steaming, the latter can be considered as the most favorable to preserve highest level of GLS and their deriviatives. Therefore, a mild-processing strategic approach for GLS or their derivatives in food is recommended, in order to minimize the loss of actual bioactive impact. Finally, the human gut microbiota is influenced by Brassica-rich diet and can contribute in certain conditions to the increasing of GLS bioavailability but further studies are needed to assess the actual role of microbiomes in the bioavailability of healthy glucosinolate derivatives.