Variations of chromium and nickel content during industrial processing of white asparagus

The influence of certain industrial processing operations of white asparagus (Asparagus officinalis, L.) on concentrations of chromium and nickel was studied. Samples of white asparagus were taken during the following operations of the industrial processing: reception and selection of raw material (fresh asparagus), after machine-washing (washed asparagus), after peeling (peeled asparagus) and on completion of the blanching operation (blanched asparagus). Asparagus samples were selected for two varieties (‘Desto’ and ‘Sur’), four diameters (9–11 mm, 11–14 mm, 14–19 mm and > 19 mm) and three portions of spear (tip, middle and rest). The mean concentrations found for chromium and nickel were 1.37 ± 0.94 and 5.53 ± 1.17 (mg kg−1 dry weight), respectively. By means of analysis of variance, statistically significant differences (P < 0.001) were determined between the different processing operations for the chromium and nickel (P < 0.05) concentrations. Scheffé multiple range analyses (P < 0.05) were applied for the processing, diameters and portion factors, separately, and homogeneous groups were formed which indicated the influence of each one of these factors on the contents of chromium and nickel.