The effects washing carrots in solutions of hydrogen peroxide on the microbial and carotenoid quality of juice and salads

This study assesses the microbial and carotenoid quality of juice and salad obtained from carrots washed in water with the addition of hydrogen peroxide (H₂O₂) in various concentrations, and for various lengths of treatment. The carrots were dipped in 1, 5 and 10% solutions of H₂O₂ for 1 or 2 min, and quality assessments made on the basis of the degree of microbial contamination, by determining total bacteria count and the most probable count of coliforms. Changes in the content of caroteinoid pigments, that is, α-carotene, β-carotene and lutein, were determined by the HPLC method as well as retinol equivalents. From the results obtained, it was deduced that the washing of carrots in 5 and 10% solutions of H₂O₂ for 2 min had the strongest antimicrobial effect, because it resulted in a reduction of microbial contamination by two logarithmic cycles. The same solutions produced a limited decrease in α-carotene and β-carotene content and the retinol equivalent in carrot juice, but they had no effect on the level of these constituents in salads.