Efficacy of chlorine, peroxyacetic acid and mild-heat treatment on the reduction of natural microflora and maintenance of quality of fresh-cut calçots (Allium cepa L.)

Calçots are the immature floral stems of the second-year onion (Allium cepa L.) resprouts with economic importance in Spain. The effect of sodium hypochlorite, peroxyacetic acid and mild heat treatment on the microbiological, physicochemical and visual quality of calçots after disinfection and the storage period of 15 d at 4 ºC was studied. Previous minimal processing operations for the disinfection helped to reduce the population of aerobic mesophilic bacteria and yeast and moulds compared to the harvest product. Calçots subjected to a mild-heat treatment (55 °C for 60 s) presented the highest reduction of aerobic mesophilic bacteria. Despite being mildly thermally-treated, they showed higher fresh weight loss (around 3%) than the rest of the disinfected calçots during storage and they obtained the highest quality visual scores after 15 d of storage with a good acceptance of the product. Microbial reductions obtained after peroxyacetic acid treatment were in the same range as those obtained after the sodium hypochlorite treatment. In addition, the quality of both treated samples was maintained with no differences during refrigerated storage. The results indicate that mild-heat or peroxyacetic acid decontamination treatments resulted in a good strategy for obtaining a clean and high quality fresh-cut calçot product.