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Acids in Combination with Sodium Dodecyl Sulfate Caused Quality Deterioration of Fresh-Cut Iceberg Lettuce during Storage in Modified Atmosphere Package

Guan, Wenqiang, Huang, Lihan, Fan, Xuetong
Journal of food science 2010 v.75 no.8 pp. S435
carbon dioxide, bacterial contamination, texture, levulinic acid, sulfates, citric acid, chlorine, head lettuce, modified atmosphere packaging, Escherichia coli O157, storage time, sensory properties, cell respiration, food pathogens, sodium dodecyl sulfate, fresh-cut foods, enzymatic browning, oxygen, food preservatives
Recent studies showed that sodium acid sulfate (SAS) and levulinic acid (LA) in combination with sodium dodecyl sulfate (SDS) was effective in inactivating human pathogens on Romaine lettuce. The present study investigated the effects of LA and SAS in combination with SDS (as compared with citric acid and chlorine) on the inactivation of E. coli O157:H7 and sensory quality of fresh-cut Iceberg lettuce in modified atmosphere packages during storage at 4 °C. Results showed that LA (0.5% to 3%) and SAS (0.25% to 0.75%) with 0.05% SDS caused detrimental effects on visual quality and texture of lettuce. LA- and SAS-treated samples were sensorially unacceptable due to development of sogginess and softening after 7 and 14 d storage. It appears that the combined treatments caused an increase in the respiration rate of fresh-cut lettuce as indicated by higher CO₂ and lower O₂ in modified atmosphere packages. On the positive side, the acid treatments inhibited cut edge browning of lettuce pieces developed during storage. LA (0.5%), SAS (0.25%), and citric acid (approximately 0.25%) in combination with SDS reduced population of E. coli OH157:H7 by 0.41, 0.87, and 0.58 log CFU/g, respectively, while chlorine achieved a reduction of 0.94 log CFU/g without damage to the lettuce. Therefore, compared to chlorine, LA and SAS in combination with SDS have limited commercial value for fresh-cut Iceberg lettuce due to quality deterioration during storage.