Quality retention of minimally processed spinach using low-dose ozonated water during storage


Abstract: The use of ozone for the sanitization of fresh-cut produce has been postulated during all steps of the cold chain from harvest to consumption. However, little is known about its effects on the postharvest quality of minimally processed spinach. In the present study, the effects of different doses of ozone on the storage life and quality of minimally processed spinach were determined and compared with sodium hypochlorite. Minimally processed spinach samples were subjected to 4 treatments: immersion in sodium hypochlorite solution (100 ppm) as control, and exposure to 3 different ozonated water (0.5,1 and 2 ppm) for 10 min. Treated spinach samples were packaged in modified atmosphere packaging and stored at 0 ºC and 90 ± 5% relative humidity for 25 days. After each cold storage period, the spinach samples were kept for one day at 20 ºC and 60 ± 5% relative humidity for shelf life studies. During cold storage and shelf life, weight loss, leaf color, SPAD value, respiration rate, gas composition in package, soluble solids content (SSC), and visual quality were determined. In general, weight losses of the spinach samples were delayed by ozone treatments, especially in low doses. The best suppressing dose for respiration rate of minimally processed spinach was 0.5 ppm, among all treatments. Additionally, the 0.5 ppm ozone treatment preserved vivid green color and visual quality of the spinach leaves better than those treated with higher doses and sodium hypochlorite. Although 1 and 2 ppm ozone treatments retarded quality losses by suppressing the respiration rates of spinach, some undesirable results were obtained from these doses due to their higher oxidative properties. The 0.5 ppm, therefore, can be considered as limit dose for postharvest treatments in minimally processed spinach. These findings revealed that ozonated water with appropriate doses can be used instead of sodium hypochlorite for minimally processed spinach during storage.

Keywords: Cold storage, fresh-cut, ozone, quality loss, Spinacia oleracea

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