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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #368621

Research Project: Evaluation and Maintenance of Flavor, Nutritional and Other Quality Attributes of Fresh and Fresh-Cut Produce

Location: Food Quality Laboratory

Title: A novel in-flight washing system on bacterial reduction and quality of fresh-cut lettuce

item Zhou, Bin
item Luo, Yaguang - Sunny
item TENG, ZI - Orise Fellow
item Millner, Patricia
item PEARLSTEIN, ARNE - University Of Illinois

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2020
Publication Date: 8/10/2020
Citation: Zhou, B., Luo, Y., Teng, Z., Millner, P.D., Pearlstein, A. 2020. A novel in-flight washing system on bacterial reduction and quality of fresh-cut lettuce. Food Control.

Interpretive Summary: A novel in-flight washing system (IFW) for cleaning fresh and freshly-cut produce is proposed as an alternative to traditional flume washing. This system sprays a produce-washing liquid upwardly onto fresh-cut produce falling downwardly, and removes loosely bound organic material and dirt from the produce surface.This study was carried out to evaluate the effects of IFW on the quality and safety of chopped lettuce. The results showed that chopped Iceberg lettuce washed with the IFW system, using 200mg/L of free chlorine, has higher overall quality scores than lettuce flume-washed with 20 mg/L free chlorine, and also has a lower population of inoculated generic bacteria E. coli and natural microorganisms over a fourteen day storage period. This new technology improves the quality and safety of fresh-cut produce compared to flume washing, and will benefit produce growers and packers as well as consumers.

Technical Abstract: A novel vertically oriented in-flight washing system (IFW) for cleaning and disinfecting fresh and freshly-cut produce is described. IFW was designed to inject liquid and gaseous sanitizing solutions upwardly, countering downward motion of produce from gravitation, promoting uniform exposure to sanitizers through produce tumbling and reorientation while suspending in air. In this pilot plat scaled study, the effect of IFW on microbial reduction and product quality was compared against conventional flume. Chopped iceberg lettuce (2.5 cm x 2.5 cm) with and without inoculation of a cocktail of three generic E. coli strains passed through the IFW with either 20 or 200 mg/L of free chlorine, a flume wash with 20 mg/L of free chlorine, or the combination of IFW and flume wash. Microbial reduction (including inoculated generic E. coli, aerobic plate count (APC), yeast and mold (YM)), and quality parameters (sensory attributes, and tissue membrane integrity) were evaluated after 0, 7, and 14 days of storage at 5 °C. When washed only in the IFW with 200 mg/L of free chlorine, 1 log CFU/g reduction in E. coli was observed on Day 0, and 1.44 log CFU/g on Day 14, which is greater than or comparable to flume washing with 20 mg/L free chlorine. The APC and YM values for produce washed with 200 mg/L IFW were the lowest among all treatments. The sensory evaluation results showed that lettuce from IFW at 200 mg/L has the highest overall quality score among all treatments. These results indicate that IFW can improve postharvest washing efficiency compared to conventional flume washing, while also achieving improved fresh-cut produce safety.