Highlights13 glucosinolate and 11 flavonol compounds identified across 35 rocket accessions.Several flavonol compounds are newly identified in Eruca and Diplotaxis species.Commercial varieties show enhanced flavonol concentrations but low glucosinolates.We stress the importance of consistent and commercially focused experimental design.

Brassicaceae plants are renowned for their taste, aroma and trigeminal characteristics; predominantly bitter taste, sulfurous aroma, and pungency. Compounds responsible for these sensations include the glucosinolates (GSLs) and their hydrolysis products, particularly isothiocyanates (ITCs), but also sulfur-containing volatile compounds. This article reviews the relative importance of taste and flavor perceptions resulting from such compounds; collating evidence from papers where findings are based on sensory analytical correlations, and those that have extracted specific compounds prior to sensory evaluation. Where specific GSLs impart bitterness and many ITCs impart pungency, this is clearly not true for all GSLs and ITCs. Designing crop improvement strategies for sensory traits based on total GSL content would be flawed, as it does not consider the relative differences in sensory characteristics of different GSLs and ITCs, nor the contribution from other GSL hydrolysis products. In addition, some Brassicaceae plants are consumed raw, whilst others are cooked; this affects not only the hydrolysis of GSLs, but also the generation and release of sulfides. Therefore, in breeding new plant varieties, it is prudent to consider the individual GSLs, the typical cooking conditions the plant is subjected to, enzyme stability, and resultant composition of both GSL hydrolysis products (including ITCs) and sulfides.

Rocket species have been shown to have very high concentrations of glucosinolates and flavonols, which have numerous positive health benefits with regular consumption. This review highlights how breeders and processors of rocket species can utilize genomic and phytochemical research to improve varieties and enhance the nutritive benefits to consumers. Plant breeders are increasingly looking to new technologies such as HPLC, UPLC, LC-MS, and GC-MS to screen populations for their phytochemical content to inform plant selections. This paper collates the research that has been conducted to date in rocket and summarizes all glucosinolate and flavonol compounds identified in the species. The paper emphasizes the importance of the broad screening of populations for phytochemicals and myrosinase degradation products, as well as unique traits that may be found in underutilized gene bank resources. This review also stresses that collaboration with industrial partners is becoming essential for long-term plant breeding goals through research.

HighlightsExtensive phytochemical & sensory analysis conducted on 7 rocket salad accessions.Polyatomic ion & amino acid concentrations vary significantly between accessions.Isothiocyanates & sulfur volatiles associated with hotness & bitterness.‘Green’ VOCs & amino acids negatively associated with pungent sensations.Glucoraphanin & glucoerucin not correlated with sensory attributes.

HighlightsWe present a robust method for VOC analysis from rocket salad packaging headspace.TD-GC–TOF-MS putatively identified 39 volatile compounds.VOC profiles for Eruca sativa varied significantly between accessions.Isothiocyanate compounds degrade significantly over shelf-life.Changes in VOC profiles could provide a useful tool for assessment of leaf quality.

HighlightsGlucosinolates, isothiocyanates and amino acids increase significantly over time.Glucoraphanin is not significantly affected by harvesting and processing.Sulforaphane significantly increases after processing in E. sativa cultivars.Bacterial load of leaves is correlated with glucosinolate and amino acid abundance.Commercial processing may increase the nutritional value of E. sativa to consumers.

It is widely accepted that the distinctive aroma and flavour traits of Brassicaceae crops are produced by glucosinolate (GSL) hydrolysis products (GHPs) with other non-GSL derived compounds also reported to contribute significantly to their aromas. This study investigated the flavour profile and glucosinolate content of four Brassicaceae species (salad rocket, horseradish, wasabi, and watercress). Solid-phase microextraction followed by gas chromatography-mass spectrometry and gas chromatography-olfactometry were used to determine the volatile compounds and odorants present in the four species. Liquid chromatography-mass spectrometry was used to determine the glucosinolate composition, respectively. A total of 113 compounds and 107 odour-active components were identified in the headspace of the four species. Of the compounds identified, 19 are newly reported for ‘salad’ rocket, 26 for watercress, 30 for wasabi, and 38 for horseradish, marking a significant step forward in understanding and characterising aroma generation in these species. There were several non-glucosinolate derived compounds contributing to the ‘pungent’ aroma profile of the species, indicating that the glucosinolate-derived compounds are not the only source of these sensations in Brassicaceae species. Several discrepancies between observed glucosinolates and hydrolysis products were observed, and we discuss the implications of this for future studies.

HighlightsTAS2R38 bitterness perception does not wholly determine liking of rocket.Hotness is the main attribute on which consumers base their liking not bitterness.Some consumers prefer mild sweet accessions low in glucosinolates and pungent VOCs.Glucoraphanin imparts no significant influence on liking or sensory perceptions.Sugar-glucosinolate/isothiocyanate ratios are important for hotness perceptions.