Effectiveness of chlorine washing disinfection and effects on the appearance of artichoke and borage

Aim: Optimal conditions for chlorine application to obtain a reasonable decrease in the microbial counts without damaging the appearance of artichoke and borage have been established. Methods and Results: The influence of chlorine concentration (0-200 mg l-1), pH, addition of organic acids, contact time and presence of protective structures on the microflora and vegetal appearance were studied. When pH was not controlled the effect of chlorine depended on its concentration until the pH increase caused by addition of chlorine reached 8.8. Any further increase in chlorine concentration was nullified by the pH increase. When pH was adjusted to 4.5 with acetic acid, the effectiveness increased with concentration. However, the use of citric acid to control pH caused a sharp decrease in effectiveness at concentration about 250 mg l-1. The higher effectiveness of chlorine on homogenized plant extracts compared with the whole plant showed the impact of the vegetal structures on the resistance of the microorganisms. For artichoke, a relationship between the effectiveness of chlorine disinfection and its structures was also found. Extended washing times did not affect the total counts. However, in both vegetables, the appearance was affected by the extended contact times. Conclusions: The solutions rendering the highest microbial reduction with minimum damages were: 50 mg l-1 free chlorine without pH control for artichoke and 100 mg l-1 free chlorine at pH 7.0 for borage. Significance and Impact of the Study: Specific conditions for chlorine disinfection of artichoke and borage were determined to reduce the microorganisms in minimally processed artichoke and borage without damaging their appearance