The effects of immersion methods and concentration of ozonated water on the microbial counts and the quality and sensory attributes of fresh-cut broccoli

The effects of immersion methods and concentrations of ozonated water on natural microbial contamination as well as the quality and sensory attributes of fresh-cut broccoli were studied. The first group of fresh-cut broccoli was immersed in air-ozonated water (containing 0.56 ppm ozone [O3]) for 5 min and remained immersed in this water for 5 min (i.e., low O3 concentration and long contact time; LL). The second group of fresh-cut broccoli was immersed in O2 gas-ozonated water (containing 1.60 ppm O3) for 5 min and remained immersed in this water for 3 min (i.e., high O3 concentration and short-contact time; HS). Fresh-cut broccoli treated with tap water served as the control. All samples were stored at 4°C for 6 days. The results revealed that washing fresh-cut broccoli with ozonated water (LL and HS) and tap water (control) reduced the amount of microbes compared with the initial microbial loads of unwashed fresh-cut broccoli. HS was the most effective treatment with regard to reducing aerobic bacteria, coliforms, and yeasts and molds throughout storage to ranges of 1.41-2.61, 0.55-1.75, and 1.46-1.71 log CFU.g^-1FW, respectively. Furthermore, this treatment did not have negative effects on color (lightness, a*, b*, and hue angle values), chlorophyll content, or sensory attributes (overall visual quality, visible color, and odor). The LL treatment reduced the microbial counts in fresh-cut broccoli on the first day after the treatment; however, the quality and sensory attributes of the LL-treated broccoli were significantly decreased compared with the control. The results indicate that treating fresh-cut broccoli with water ozonated with a high concentration of O3 (1.60 ppm) for 5 min followed by immersion in the same water for 3 min reduces natural microbial contamination without any negative effects on the quality or sensory attributes of the broccoli.