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Food Protection Trends
Abstracts - December 2003
Monte Carlo Simulation of the Shelf Life of Pasteurized
Milk as Affected by Temperature and Initial Concentration of Spoilage Organisms
Acceptability of Irradiated Food to Restaurant Managers
Monte Carlo Simulation of the Shelf
Life of Pasteurized Milk as Affected by Temperature and Initial Concentration
of Spoilage Organisms
Donald W. Schaffner,* Jennifer McENTIre, Siobain Duffy, Rebecca
Montville andSarah Smith
Food Science Building, Rutgers University, 65 Dudley Road, New Brunswick, NJ
08901
SUMMARY
Predictive microbiology and quantitative microbial risk assessment are rapidly
developing disciplines that use mathematical models to quantitatively estimate
the presence and growth of microbes in food products. This report explains how
these techniques were used in troubleshooting a milk spoilage problem.
The central objective of this article is to demonstrate the concept and value
of Monte Carlo simulation in a simple manner, such as could be adapted by interested
food processors and used as a guide for their own studies.
Generation times, initial concentrations of spoilage organisms
found in milk, and storage temperature data were fit to probability distribution
functions. Monte Carlo simulation results indicate that slight decreases (of
2.1ºC) in average storage temperatures significantly increased the simulated
shelf life of pasteurized milk (more than 50% less psychrotrophic spoilage by
14 days), especially in those simulation samples contaminated with mesophilic
bacteria (almost 75% less spoilage). When the average storage temperature
was reduced by 2.1ºC, storage temperature variability by 1ºC, and average
initial microbial contamination levels by 0.5 Log10 CFU/ml, this significantly
lengthened shelf life when either mesophilic (1% spoilage by 14 days) or psychrotrophic
(9% spoiled by 14 days) microbes were present.
Microbial simulation tools used primarily for food safety
risk assessment can also be used to predict microbial spoilage and may be of
value to the food industry.
Acceptability of Irradiated Food
to Restaurant Managers
Kranti Mulik,* John A. Fox, andMichael A. Boland
Dept. of Agricultural Economics, Kansas State University, Manhattan, KS 66506
SUMMARY
Restaurant managers in Kansas were surveyed to determine their attitudes toward
food irradiation and their willingness to buy and serve irradiated hamburger
patties. Results indicate that 54% of restaurants would purchase irradiated
ground beef if it were available at the same price as regular product.
Only 11% indicated that they would not purchase irradiated product. Females
and respondents from restaurants with a policy of cooking ground beef to at
least 166°Fwere less likely to choose irradiation. However, among
respondents preferring irradiated to regular ground beef, females valued the
process higher than males. Estimated median willingness-to-pay for irradiation
for females was 6.25c/lb and for males was 3.94c/lb.
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