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P1-122 Application of Pulsed Light (PL) to Decontaminate Escherichia coli O157:H7 and Salmonella and Preserve Quality on Raw Raspberries

Monday, August 4, 2014
Exhibit Hall D (Indiana Convention Center)
Wenqing Xu, University of Delaware, Newark, DE
Haiqiang Chen, University of Delaware, Newark, DE
Changqing Wu, University of Delaware, Newark, DE
Introduction: Raspberries have been associated with Cyclospora and norovirus outbreaks. Foodborne pathogens such as Escherichia coli O157:H7 and Salmonella may also contaminate raspberries because they share fecal-oral route with Cyclospora and norovirus. Raw raspberries cannot be washed with sanitizers due to their delicate texture. Thus, it has been a challenge to maintain the microbial safety without compromising the quality of raspberries. Novel techniques such as pulsed light (PL) may have the potential to meet the challenge.

Purpose: The purpose of this study was to investigate the potential of applying PL on pathogen decontamination and quality protection of raw raspberries.

Methods: Raw raspberries were spot inoculated with E. coli O157:H7 and Salmonella. Decontamination efficacy of PL on both pathogens was investigated after 5, 15 or 30s PL treatment. Also, survival population of pathogens was evaluated during 10 days at 4°C. Quality of the raspberries including the color, texture, total phenolic content (TPC), total anthocyanin content (TAC), total bacterial count (TBC) as well as total mold and yeast (TMY) were tested to observe the possible quality loss during 10 days of shelf life.

Results: The results showed that PL for 5, 15 or 30s was effective for E. coli O157:H7 (with 3.6, 3.4 and 3.9 log CFU/g reduction) and Salmonella (with 3.4, 4.0 and 4.5 log CFU/g reduction) decontamination on raspberries. During storage, the survival population of both pathogens on treated raspberries maintained at significantly lower levels compared with untreated ones. Color, texture, TPC and TAC of raspberries were not affected by 5 or 15s PL treatment during 10 days storage. While quality defects were observed on 30s PL treated raspberries after 5 days storage. PL also reduced TBC and TMY during shelf life.

Significance: This study suggests that PL has the potential to be used in the raspberry industry.

Back to: Poster Session - Applied Laboratory Methods, Produce, Low-water Activity, Beverages and Water
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