Location: Food Quality Laboratory
Title: Quality of Iceberg and Romaine lettuce treated by combinations of sanitizer, surfactant, and ultrasound Authors
|Salgado, Sindy -|
|Pearlstein, Arne -|
|Feng, Hao -|
Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2013
Publication Date: December 10, 2014
Citation: Salgado, S.P., Pearlstein, A.J., Luo, Y., Feng, H. 2014. Quality of Iceberg and Romaine lettuce treated by combinations of sanitizer, surfactant, and ultrasound. LWT - Food Science and Technology. 56:261-268. Interpretive Summary: Ultrasound treatment is a new technology that shows great promise in improving pathogen-killing efficacies and food safety of fruit and vegetable products. However, treatment conditions must be optimized in order to avoid the damage of ultrasound to plant tissues and loss of the product quality and shelf life. Teaming up with University of Illinois researchers, USDA-ARS scientists at Beltsville Agricultural Research Center cooperatively evaluated the effect of ultrasound and surfactant alone, and in combinations with commonly used anti-microbial compounds on the quality retention of fresh-cut lettuce. Results indicate that the optimized ultrasound and sanitizer treatment not only improved pathogen reduction, but also maintained the quality and shelf life of the fresh-cut produce. These findings provide important information to the research community and the produce industry regarding the further development and adoption of this novel technology.
Technical Abstract: We report an investigation of the individual and combined effects of sonication, two sanitizers (chlorine and Tsunami 100®) and a surfactant (sodium dodecyl sulfate (SDS) on the quality of fresh-cut Iceberg and Romaine lettuce. Lettuce samples were treated for 1 minute with and without ultrasound in a custom-designed ultrasonic tank containing one of the following treatment solutions: tap water; chlorine (100 mg L-1 free chlorine); Tsunami 100® (80 mg L-1 peroxyacetic acid), and a combination of Tsunami 100® with 0.1% (w/v) SDS. Washed samples were packed under modified atmosphere conditions and stored at 4 ºC for up to 14 days. Changes in headspace gases, texture, color, tissue damage, visual quality, and populations of aerobic mesophile bacteria, and yeasts and molds 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 100® and Tsunami 100® + SDS were recorded. After 14 days of storage, the tissue damage expressed by electrolyte leakage rate (ECR), total color difference, firmness, and total aerobic plate counts were not significantly different for all the treatments in two types of lettuce samples (P>0.05). Treatment of Iceberg lettuce with sonication in combination with Tsunami 100® or Tsunami 100® + 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.