Evaluating the efficacy of three sanitizing agents for extending the shelf life of fresh-cut baby spinach: food safety and quality aspects

The aims of this project were to: 1) compare the antimicrobial efficacy and feasibility of three sanitizers including chlorine dioxide (ClO2 ), neutral electrolysed water (EW) and peroxyacetic acid (PAA) for the treatment of fresh baby spinach leaves, and 2) to investigate the shelf life and quality attributes of spinach treated with these sanitizers. In the experiment for food safety, spinach leaves were inoculated with Salmonella Typhimurium and then treated by immerging in cold solutions of PAA, ClO2, EW at different concentrations. Salmonella Typhimurium and total viable count (TVC) were determined immediately before and after the treatment. The treatment with 20 mg/L ClO2 solution resulted in the highest reductions of S. Typhimurium and TVC (by 1.6 +/- 0.1 log CFU/g) compared to other treatments. In the experiment for the shelf life of spinach, the samples were stored at 4 degrees C for 13 days after being treated with 75 mg/L PAA, 60 mg/L free chlorine (FCh) EW and 20 mg/L ClO2 solutions. The results showed that TVC was significantly influenced by the treatments and storage time. At day 0, TVC of all treated samples was significantly lower than this of the control and the TVC of sample treated with ClO2 was the lowest. However, by day 10, the TVC was not significantly different among the treated samples and the control. For the sensory qualities and physio-chemical properties of the spinach leaves, the treatment with ClO2 showed significant reduction in quality of the treated sample since day 7 of the storage while other treatments did not show any significant effect on those parameters during the storage. In summary, although the treatment with 20 mg/L ClO2 solution resulted in the highest antimicrobial efficacy against S. Typhimurium and TVC of spinach leaves, it also caused negative effects to the quality of spinach during the storage.