Influence of harvest time on the quality of some leek cultivars grown in Italy

Four leek cultivars (Arial, Atal, HF1 Charlton and San Giovanni) were colle cted from 4 November every 3 weeks for 5 months with the aim to evaluate th e right period of the harvest. For this goal three parameters were used: ar oma compounds, yield per hectare and dry matter. Firstly, the green part of the leek was cut of leaving only the white portion. For the analysis of th e volatile compounds the samples were divided longitudinally and then slice d horizontally by hand. The volatile compounds were extracted from 300 g of samples using the microwave technique and then adsorbed on KS 112 apolar r esin. The aroma compounds were eluted From the resin with solvent. After co mpletely removing the solvent, the volatile extracts were quali-quantitativ ely analysed by GC/MS-SIM. The results showed that the 4 cultivars had all the characteristic volatile compounds of Allium porrum spp. L.; in particular disulfides, trisulfides, trithiolanes, thiofenes, and even dithianes were detected. The comparison of the mean values of methyl propyl disulfide and the other two parameters pointed out that the optimal harvest time of the leek cultiv ars can occur between the 6(th) and 15(th) week from the first harvest.