Efficacy of nanoemulsified benzyl isothiocyanate for controlling Escherichia coli O157 on spinach at the pre-harvest level

Authors: Yin, Hsin Bai; CHEN, CHI-HUNG - Oak Ridge Institute For Science And Education (ORISE); MAYER, CHRISTINE - Wilson College; HARRIGER, DANA - Wilson College; Patel, Jitu

Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Recent outbreaks linked to the contaminated spinach highlight the need for identifying effective natural approaches to improve Introduction: Recent outbreaks linked to the contaminated spinach highlight the need for identifying effective natural approaches to improve produce safety at pre-harvest level. Purpose: Efficacy of nanoemulsified benzyl isothiocyanate (nano BIT) as a pre-harvest antimicrobial treatment against Escherichia coli O157 on spinach grown in high tunnel was investigated. Methods: Spinach cultivars “Lakeside”, “Matador”, “Butterfly”, and “Regiment” grown in high tunnel were spray-inoculated with E. coli O157:H12 (5.5 log CFU/g) as non-pathogenic surrogate for E. coli O157:H7 five days prior to harvest. Inoculated spinach plants were spray-treated with 0.5% pure or nano BIT. On 0, 3, and 5 days, four samples from each group (20 g/sample; N=144) were collected and surviving E. coli O157:H12 populations were determined by plating on selective agar. The droplet size of nano BIT was determined by using Zetasizer. Data were analyzed by SAS and the differences were detected at P<0.05 using Fisher's least significance test. Results: Both pure and nano BIT immediately reduced E. coli O157:H12 by 1.0 log CFU/g on leaves of all spinach cultivars compared to control spinach leaves on day 0 (P<0.05). On day 3, nano BIT exerted significantly greater antimicrobial effect than the pure BIT. Pure BIT significantly reduced E. coli O157:H12 populations by 1.4 and 2 log CFU/g on “Lakeside” and “Matador” cultivars as compared to control, whereas an additional 1 log reduction was observed from nano BIT-treated samples. On day 5, nano BIT treatment significantly reduced E. coli O157:H12 populations on “Butterfly”, “Matador”, and “Lakeside” cultivars by 1.3, 1.8, and 2.5 log CFU/g, respectively, as compared to the control. The color of nano BIT-treated spinach leaves was comparable to control leaves on 0-3 days. The droplet size of freshly prepared nano BIT was 15.7±0.3 nm. Significance: Nanoemulsified BIT can be potentially used as a pre-harvest antimicrobial treatment against E. coli O157 on spinach. produce safety at pre-harvest level. Purpose: Efficacy of nanoemulsified benzyl isothiocyanate (nano BIT) as a pre-harvest antimicrobial treatment against Escherichia coli O157 on spinach grown in high tunnel was investigated. Methods: Spinach cultivars “Lakeside”, “Matador”, “Butterfly”, and “Regiment” grown in high tunnel were spray-inoculated with E. coli O157:H12 (5.5 log CFU/g) as non-pathogenic surrogate for E. coli O157:H7 five days prior to harvest. Inoculated spinach plants were spray-treated with 0.5% pure or nano BIT. On 0, 3, and 5 days, four samples from each group (20 g/sample; N=144) were collected and surviving E. coli O157:H12 populations were determined by plating on selective agar. The droplet size of nano BIT was determined by using Zetasizer. Data were analyzed by SAS and the differences were detected at P<0.05 using Fisher's least significance test. Results: Both pure and nano BIT immediately reduced E. coli O157:H12 by 1.0 log CFU/g on leaves of all spinach cultivars compared to control spinach leaves on day 0 (P<0.05). On day 3, nano BIT exerted significantly greater antimicrobial effect than the pure BIT. Pure BIT significantly reduced E. coli O157:H12 populations by 1.4 and 2 log CFU/g on “Lakeside” and “Matador” cultivars as compared to control, whereas an additional 1 log reduction was observed from nano BIT-treated samples. On day 5, nano BIT treatment significantly reduced E. coli O157:H12 populations on “Butterfly”, “Matador”, and “Lakeside” cultivars by 1.3, 1.8, and 2.5 log CFU/g, respectively, as compared to the control. The color of nano BIT-treated spinach leaves was comparable to control leaves on 0-3 days. The droplet size of freshly prepared nano BIT was 15.7±0.3 nm. Signific