“Relating rocket salad (Diplotaxis and Eruca spp.) glucosinolate and sensory attributes”

Glucosinolates are an important group of sulfur-containing metabolites, typical of the Brassicaceae family, presently highly valued for putative anti-carcinogenic properties (1). Glucosinolates and their breakdown products (isothiocyanates, thiocyanates and nitriles) are responsible of the sensory properties of the Brassica vegetables, with also potential adverse effects on acceptance, at high concentrations. By consequence, breeding of vegetable crops was often addressed at lowering their content (2), with potential contrast between health promoting and sensory properties. Eruca sativa L. (cultivated rocket) and Diplotaxis tenuifolia L. (wild rocket) are highly. Previous investigation on several Diplotaxis and Eruca species, with ample range of glucosinolate appreciated vegetables, characterised by peculiar spicy flavour and pungency, in relation to their glucosinolate content and composition, indicated a negative relation between glucosinolate content and acceptance (3). The aim of this study was to examine typical cultivated material for sensory and analytical characters. Preliminarily, a vocabulary and a simple sensory profile for rocket salad evaluation were developed. Nine assessors were trained for sensory evaluation of fresh samples, in order to develop descriptive terms for the aroma and flavor attributes, and design an appropriate record sheet. After that, the sensory attributes of thirty-seven Eruca and Diplotaxis accessions of different geographic origin were evaluated. All samples were analyzed for total and individual glucosinolate content by high performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS). Within the relatively limited range of glucosinolate content and composition of this cultivated material, no adverse effect of glucosinolates on acceptance was detected. On the contrary, there was some evidence of a positive relation between glucosinolate content and pungency, also related to typical rocket salad flavour. Therefore, no possible adverse effect of high glucosinolates on intake and health promoting properties was brought out. Potential high value types for breeding were also individuated.