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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL ECOLOGY AND SAFETY OF FRESH ON-FARM ORGANICALLY GROWN PRODUCE Title: Impact of essential oils on microbial and sensory qualities of spinach leaves

Authors
item Yossa, Nadine -
item Patel, Jitu
item Millner, Patricia
item Lo, Martin -

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 23, 2011
Publication Date: April 27, 2011
Citation: Yossa, N., Patel, J.R., Millner, P.D., Lo, M. 2011. Impact of essential oils on microbial and sensory qualities of spinach leaves. BARC Poster Day.

Technical Abstract: Foodborne outbreaks associated with consumption of fresh produce have increased in recent years. Chlorine is widely used as a produce wash to control pathogens on fresh produce; however, it is less effective in presence of organic matter. Consumers’ preference for natural antimicrobials over chemicals has led to evaluate the effect of natural antimicrobials for controlling pathogens on fresh produce. The efficacy of cinnamaldehyde and sporan alone, or in combination with acetic acid in reducing E. coli O157:H7 and Salmonella on spinach leaves was investigated. Spinach leaves were inoculated with a cocktail of five-strain Salmonella or E. coli O157:H7 (5 log cfu/g), air-dried for 30 min, and then immersed in a treatment solution containing cinnamaldehyde or Sporan (600, 800, and 1000 ppm) alone, or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and analyzed after washing, and during 14-days storage at 4°C. Inoculated leaves washed with water were used as control. The samples were plated on XLT4 and SMAC agar for Salmonella and E. coli O157:H7 populations, respectively. Color (Hunter L, a, b color classification) and texture (TA-XT2 texture analysis) characteristics of antimicrobial-treated leaves were analyzed. Un-inoculated leaves immersed in treatment solutions were used for color and texture analysis. Treatment with 800 ppm cinnamaldehyde or 1000 ppm sporan significantly reduced E. coli O157:H7 and Salmonella on spinach leaves. Combination of acetic acid with cinnamaldehyde or sporan further reduced these pathogens on spinach leaves; however, the effect of acetic acid was not significant. E. coli O157:H7 was more sensitive to cinnamaldehyde treatment compared to Salmonella. Bacterial population decreased significantly during storage. The quality (color and texture) of sporan-treated leaves after 14 days were not significantly different from control-treated spinach leaves. However, the cinnamaldehyde adversely affected the texture of spinach leaves at 7 days. Results indicate that these natural oils could be used to reduce E. coli O157:H7 and Salmonella on organic spinach without affecting the sensory quality

Last Modified: 12/21/2014
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