Moderate and High Doses of Sodium Hypochlorite, Neutral Electrolyzed Oxidizing Water, Peroxyacetic Acid, and Gaseous Chlorine Dioxide Did Not Affect the Nutritional and Sensory Qualities of Fresh-Cut Iceberg Lettuce (Lactuca sativa Var. capitata L.) after Washing
2009
Vandekinderen, Isabelle | Camp, John Van | Meulenaer, Bruno De | Veramme, Kim | Bernaert, Nathalie | Denon, Quenten | Ragaert, Peter | Devlieghere, F (Frank)
Besides the traditionally used sodium hypochlorite (20 and 200 mg L-1), alternative sanitizers such as peroxyacetic acid (80 and 250 mg L-1) and neutral electrolyzed oxidizing water (4.5 and 30 mg L-1 free chlorine) as well as chlorine dioxide gas (1.54 mg L-1) were evaluated for their efficiency in reducing the microbial load of fresh-cut iceberg lettuce. An additional rinsing step with tap water and cooling of the sanitizing solutions, which are obvious for the fresh-cut industry, were not performed within the current study. The high doses of sodium hypochlorite and peroxyacetic acid tested within this study do not conform to the normally used concentrations within the fresh-cut industry. Neutral electrolyzed oxidizing water (30 mg L-1), peroxyacetic acid (250 mg L-1), and gaseous chlorine dioxide significantly reduced the total aerobic plate count of cut lettuce in comparison with water wash treatments alone. None of the treatments significantly affected the sensory quality of the lettuce, although small color changes were observed after colorimetric measurements. From a nutritional point of view water rinsing significantly decreased the vitamin C (maximum 35%) and phenol (maximum 17%) contents, but did not affect the carotenoid and α-tocopherol contents. Additional effects caused by adding a sanitizer to the wash water were not observed for vitamin C and phenols. Conversely, washing with 250 mg L-1 peroxyacetic acid reduced the β-carotene content by about 30%, whereas using 200 mg L-1 sodium hypochlorite reduced both the lactucaxanthin and the lutein contents by about 60%. Use of gaseous chlorine dioxide also had an impact on the lutein content (-18%). Furthermore, the α-tocopherol content was reduced by 19.7 and 15.4% when the two concentrations of neutral electrolyzed oxidizing water were used, respectively. These data represent the situation on day 0. In a next phase, shelf-life studies considering microbial and sensory quality and nutrient content should be conducted.
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