Search

The volatile profile of crushed rocket leaves ( Eruca sativa and Diplotaxis tenuifolia ) was investigated by applying Headspace Solid-Phase MicroExtraction (HS-SPME), combined with GC–MS, to an aqueous extract obtained by homogenization of rocket leaves, and stabilized by addition of CaCl 2 . A detailed picture of volatile products of the lipoxygenase pathway (mainly C6-aldehydes) and of glucosinolate hydrolysis (mainly isothiocyanates), and their dynamics of formation after tissue disruption was given. Odor-active compounds of leaves were characterized by GC-Olfactometry (GC-O) and Aroma Extract Dilution Analysis (AEDA): volatile isolates obtained by HS-SPME from an aqueous extract and by Stir-Bar Sorptive Extraction (SBSE) from an ethanolic extract were analyzed. The most potent odor-active compounds fully or tentatively identified were ( Z )- and ( E )-3-hexenal, ( Z )-1,5-octadien-3-one, responsible for green olfactory notes, along with 4-mercaptobutyl and 4-(methylthio)butyl isothiocyanate, associated with typical rocket and radish aroma. Relatively high odor potency was observed for 1-octen-3-one, ( E )-2-octenal and 1-penten-3-one. [ABSTRACT FROM AUTHOR]

Five cultivars of Eruca sativa and a commercial variety of Diplotaxis tenuifolia were grown in the UK (summer) and subjected to commercial growth, harvesting and processing, with subsequent shelf life storage. Glucosinolates (GSL), isothiocyanates (ITC), amino acids (AA), free sugars, and bacterial loads were analysed throughout the supply chain to determine the effects on phytochemical compositions. Bacterial load of leaves increased significantly over time and peaked during shelf life storage. Significant correlations were observed with GSL and AA concentrations, suggesting a previously unknown relationship between plants and endemic leaf bacteria. GSLs, ITCs and AAs increased significantly after processing and during shelf life. The supply chain did not significantly affect glucoraphanin concentrations, and its ITC sulforaphane significantly increased during shelf life in E. sativa cultivars. We hypothesise that commercial processing may increase the nutritional value of the crop, and have added health benefits for the consumer. [ABSTRACT FROM AUTHOR]

An important step in breeding for nutritionally enhanced varieties is determining the effects of the post-harvest supply chain on phytochemicals and the changes in VOCs produced over time. TD-GC–TOF-MS was used and a technique for the extraction of VOCs from the headspace using portable tubes is described. Forty-two compounds were detected; 39 were identified by comparison to NIST libraries. Thirty-five compounds had not been previously reported in Eruca sativa. Seven accessions were assessed for changes in headspace VOCs over 7 days. Relative amounts of VOCs across 3 time points were significantly different – isothiocyanate-containing molecules being abundant on ‘Day 0’. Each accession showed differences in proportions/types of volatiles produced on each day. PCA revealed a separation of VOC profiles according to the day of sampling. Changes in VOC profiles over time could provide a tool for assessment of shelf life. [ABSTRACT FROM AUTHOR]

Abstract: The present study investigates the antimicrobial activity of various solvent extracts of Eruca sativa (aerial and root) and seed oil against-antibiotic resistant Gram-negative (Escherichia coli, Pseudomoms aeruginosa and Shigella flexneri) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Among the various preparations, seed oil was the most active, exhibiting a maximum zone inhibition of 97% for Gram-positive bacteria and of 74–97% for Gram-negative bacteria. The MIC of the seed oil was found to be 65–75 and 60–70μg/ml for Gram-negative and Gram-positive bacteria, respectively. Analytical investigation on main volatile and non-volatile components was performed on seed oil. Among the formers allyl isothiocyanate (40μg/g), 3-butenyl isothiocyanate (260μg/g), 4-methylsulfinybutyl isothiocyanate (sulforaphane 743μg/g), 2-phenylethyl isothiocyanate (159μg/g) and bis(isothiocyanatobutyl)disulphide (∼5000μg/g) were determined by head space/SPME/GC–MS analysis. Free fatty acids were 1.6% w/w of the oil and overall 25 fatty acids were identified. Erucic and oleic acids were the main fatty acids both in the free (7.8 and 2.1mg/ml) and esterified forms (50.6% w/w and 14.9% w/w of total fatty acids). Unsaponifiable fraction was 1.8% w/w. Seed oil of E. sativa has promising pharmacological efficacies and ensures the presence of bio-active components responsible for the observed beneficial effects. Our findings support its use in traditional medicine as antimicrobial bioagent and highlight the potential of this food plant for its possible clinical use. [Copyright &y& Elsevier]