Sanitizing Treatment for Minimally Processed Cucumber Products - - PowerPoint PPT Presentation
Brief Blanching: An Effective Sanitizing Treatment for Minimally Processed Cucumber Products Fred Breidt and Suzanne Johanningsmeier USDA-ARS Food Science Research Unit Part II. Quality assessment for blanched refrigerated pickles with various
Fred Breidt and Suzanne Johanningsmeier USDA-ARS Food Science Research Unit
Part II. Quality assessment for blanched refrigerated pickles with various blanch times and shelf-life study up to one year. Data will also be presented for pathogen killing kinetics and modeling for food safety.
➢Determine the quality and safety of refrigerated cucumber pickles produced with a brief blanching step to reduce background microbota
➢Approved 05/04/2017, 12 months, currently with no cost extension ➢Principal Scientists:
➢ Dr. Suzanne D. Johanningsmeier ➢ Dr. Fred Breidt ➢ Ms. Lisa LaFountain, MS student (NCSU, Food Science) ➢ Mr. Robert Price (ARS Microbiology Technician)
➢Approach
➢Determine if brief blanching (80 oC for 15 s to 180 s) can reduce microbiota without detriment to quality
➢ Texture, peel color, and cured appearance development ➢ Reduction of Microbiota
➢Determine pathogen D and z values
➢ modeling log reduction
Whole size 3B cucumbers Lot A divided into 8-50 cucumber batches Control (no blanch) 15 seconds 176 °F 180 seconds 176 °F 360 seconds 176 °F Lot B divided into 10-50 cucumber batches Control (no blanch) 15 seconds 176 °F 45 seconds 176 °F 90 seconds 176 °F 180 seconds 176 °F Lot C divided into 8-50 cucumber batches Control (no blanch) 15 seconds 176 °F 90 seconds 176 °F 180 seconds 176 °F
Each treatment performed in duplicate
Washed Sampled Loaded Blanching treatment applied Thermal imaging
Cucumbers cut into spears Packed into jars 55:45 cucumber to brine ratio
Brined to equilibrate to 2.2% salt, 0.12% calcium chloride, 0.44% acetic acid, & 0.085% sodium benzoate
Figure 1: Thermal model diagram of size 3B cucumbers after blanching at 80°C
1 2 3 4 5 6 7 50 100 150 200
Log CFU/ml Time (Seconds)
Lactic Acid Bacteria (MRS) Total Aerobes (PCA) Enteric Bacteria (VRBG) LOD
Figure 2: Reduction in natural microbiota of whole cucumbers following blanch treatments at 80°C.
2 4 6 8 10 15 90 180
Mesocarp Firmness (N) Blanch Duration (Seconds)
a a
a a
➢Can consumers tell a difference between a typical refrigerated pickle and one produced with a 90 sec cucumber blanch at 176°F (80 °C)? ➢Similarity Testing on Refrigerated Pickles (62 days storage) ➢Alternative Null hypothesis (“The products are different”) ➢110 Pickle Consumers ➢Sensory Analysis -Tetrad Test
Directions: Today you will be evaluating 4 pickled cucumber samples. The samples will each have a 3-digit
samples that are most similar into two groups of two samples each. Please taste the pickle samples in the following order, from left to right:
793 314 576 207
Write the corresponding sample number for each group of similar samples into the spaces
Group A Group B _______ _______ _______ _______
Pickles produced with a 90 second blanch of whole cucumbers had minimal curing and significantly less oxidized off-flavor No blanch No Blanch 90 sec Blanch 90 second blanch
➢E. coli is one of the most acid resistant pathogens in acid and acidified vegetable products ➢Thermal processing kinetics are known for pathogenic E. coli under acid conditions, but not for microorganisms in and on fresh cucumbers ➢Existing acid killing data is not useful ➢Determine thermal processing kinetic of E. coli (D and z values) at pH 6.4, the typical pH of fresh cucumbers ➢Use kinetic parameters to model the die-off of pathogens at different depths within the cucumber ➢Use known heat transfer kinetics for cucumber tissue
z value = 15.62 oF (+/- 3.32)
The E. coli Inquisition
Temp oF Temp oC Log10 D stdev 122.0 50 2.08 0.12 125.6 52 1.70 0.06 129.2 54 1.42 0.23 132.8 56 1.44 0.06
y = -0.064x + 9.7915 R² = 0.6305 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 121 123 125 127 129 131 133 135
Log10 of D value Temperature oF
D and z value for E. coli O157:H7 at pH 6.5
*Lisa LaFountain and Robert Price
➢A heat transfer – microbial killing kinetics model will be used
➢Assumption: E. coli is distributed the same as other vegetative bacteria in the cucumber. ➢Worst case scenario: D and z values are representative of all bacteria in and on the cucumber.
➢Heat transfer kinetics from Fasina and Fleming (2001) ➢Predictions of reduction of E. coli due to blanching process. ➢Existing acid killing data for “remainder” of 5-log reduction for E. coli.
Awarded 1st Place in the International Division Poster Competition
Assisted by:
agreement with Pickle Packers International, Inc.
University College of Agriculture and Life Sciences Graduate Student Fellowship Program and the Department of Food, Bioprocessing and Nutrition Sciences at NC State
donated by Mount Olive Pickle Company
Food Science Research Unit At NC State University, Raleigh, NC Fred.Breidt@ars.usda.gov Suzanne.Johanningsmeier@ars.usda.gov