Quality of Iceberg (Lactuca sativa L.) and Romaine (L. sativa L. var. longifolial) lettuce treated by combinations of sanitizer, surfactant, and ultrasound

The effects of sonication, sanitizers and sodium dodecyl sulfate (SDS) on the quality of fresh-cut Iceberg and Romaine lettuce were examined. Lettuce samples were treated for 1min with and without ultrasound with one of the following solutions: tap water, chlorine, Tsunami, and a combination of Tsunami with 1g/L SDS. Washed samples were packed under modified atmosphere conditions and stored at 4°C for up to 14 days. Changes in headspace gases, texture, color, tissue damage, visual quality, and natural flora were determined. The O₂ concentrations and CO₂ accumulation in Romaine lettuce were not significantly different among the treatments. In Iceberg lettuce, a lower O₂ and high CO₂ content in the headspace of samples treated with Tsunami and Tsunami+SDS were recorded. After 14-day storage, the tissue damage expressed by electrolyte leakage, total color difference, firmness, and total aerobic plate counts were not significantly different among treatments in two types of lettuce samples. Treatment of Iceberg lettuce with sonication in combination with Tsunami or Tsunami+SDS did not degrade quality compared to samples treated with chlorine alone, whereas for Romaine lettuce, chlorine-treated samples had a significantly higher overall quality score than that from the other treatments.