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 blanch times and shelf-life study up to one year. Data will also be presented for pathogen killing kinetics and modeling for food safety.

Project summary ➢ 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 o C 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

Experimental Design: Whole size 3B cucumbers Lot A divided into Lot B divided into Lot C divided into 8-50 cucumber 10-50 cucumber 8-50 cucumber batches batches batches Control Control Control Each treatment performed in duplicate (no blanch) (no blanch) (no blanch) 15 seconds 15 seconds 15 seconds 176 °F 176 °F 176 °F 180 seconds 45 seconds 90 seconds 176 °F 176 °F 176 °F 360 seconds 90 seconds 180 seconds 176 °F 176 °F 176 °F 180 seconds 176 °F

Sampled Washed Process Flow Blanching treatment applied Loaded Thermal imaging

Packed into jars 55:45 cucumber to brine ratio Pickle Packing Cucumbers cut into spears Brined to equilibrate to 2.2% salt, 0.12% calcium chloride, 0.44% acetic acid, & 0.085% sodium benzoate

Thermal Modeling Figure 1: Thermal model diagram of size 3B cucumbers after blanching at 80°C

Reduction in Natural Microbiota of Whole Cucumbers 7 Lactic Acid Bacteria (MRS) 6 Total Aerobes (PCA) 5 Enteric Bacteria (VRBG) Log CFU/ml 4 3 LOD 2 1 0 0 50 100 150 200 Time (Seconds) Figure 2: Reduction in natural microbiota​ of whole cucumbers​ following blanch treatments at 80°C.

Texture Quality 10 a a a a Mesocarp Firmness (N) 8 Cucumbers 6 4 2 0 0 15 90 180 Blanch Duration (Seconds)

Texture Quality

Appearance: Peel Color

Appearance: Peel Color

Cured Appearance Development

Consumer Testing ➢ 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

Consumer Testing - Ballot Directions: Today you will be evaluating 4 pickled cucumber samples. The samples will each have a 3-digit code. Please taste a portion of each sample in the order shown below and then group the 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 below. Each number should only be used ONCE : Group A Group B _______ _______ _______ _______

Consumer Testing - Results ➢ Can consumers tell a difference between a typical refrigerated pickle and one produced with a 90 sec cucumber blanch at 176°F (80 °C)? ➢ Only 39 of the 110 pickle consumers paired the samples correctly ➢ Conclude that, “No, the products are not different”

No blanch Refrigerated Pickles 1 year of storage 90 sec Blanch No Blanch 90 second blanch Pickles produced with a 90 second blanch of whole cucumbers had minimal curing and significantly less oxidized off-flavor

Conclusions – Quality & Shelf-life ➢ A 90 second blanch at 176 °F (80 °C) could be used by processors to reduce background microbiota on whole cucumbers without significant deterioration in quality of refrigerated-type pickles ➢ The 90 second 176 °F blanch treatment of whole cucumber may extend the shelf-life of refrigerated pickles by maintaining a fresh-like appearance and flavor longer than unblanched cucumber

Pathogen killing during 90 s blanching procedure ➢ 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

The E. coli Inquisition Heat killing data* D and z value for E. coli O157:H7 at pH 6.5 2.4 y = -0.064x + 9.7915 2.2 R² = 0.6305 2.0 Log 10 of D value 1.8 1.6 Temp o F Temp o C Log 10 D stdev 122.0 50 2.08 0.12 1.4 125.6 52 1.70 0.06 1.2 129.2 54 1.42 0.23 132.8 56 1.44 0.06 1.0 121 123 125 127 129 131 133 135 z value = 15.62 o F (+/- 3.32) Temperature o F *Lisa LaFountain and Robert Price

Using the data: modeling log reduction ➢ 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.

Future work • Investigate lot to lot variability in texture degradation rates • Explore potential for shelf-life extension • Modeling log reduction for E. coli using a worst case scenario. • Possibly assess D and z values for Salmonella and Listeria as well.

Acknowledgements Ms. Lisa LaFountain, Institute of Food Technologists Annual Meeting, Awarded 1 st Place in the International Division Poster Competition

Acknowledgements • Graduate student researchers: • Ms. Lisa LaFountain Assisted by: • Ms. Clara Jones • Ms. Leah Hamilton • Ms. Jennifer Fideler • Ms. Monica Richmond • Microbiological support • Mr. Robert Price • This study was funded in part by a research agreement with Pickle Packers International, Inc. • Funding was also provided by the NC State University College of Agriculture and Life Sciences Graduate Student Fellowship Program and the Department of Food, Bioprocessing and Nutrition Sciences at NC State • Cucumbers and pickling supplies were graciously donated by Mount Olive Pickle Company

Fred.Breidt@ars.usda.gov Food Science Research Unit Suzanne.Johanningsmeier@ars.usda.gov At NC State University, Raleigh, NC