High CO(2) + Low O(2) = Burgers That Stay Fresher Longer

Overview

Objectives/Goals The objective of this project was to investigate how a high CO2/low O2 environment affects the degradation of raw hamburger patties. I hypothesized that the bag containing CO2,O2 absorbers,and the fuel cell would extend the freshness and slow the degradation of the hamburger patty to the greatest extent. The bag with CO2 and O2 absorbers would be the next freshest,and the bag with O2 absorbers only would be the third freshest. I expected that the control would spoil first. Methods/Materials I put 4 raw hamburger patties in different packaged environments in a refrigerator for 14 days: one with nothing in it except ambient air; one with O2 absorbers; one with a CO2 flush and O2 absorbers; and one with a CO2 flush, O2 absorbers, and a fuel cell to see which hamburger would appear and smell the freshest after 2 weeks. After every 4 days, I took O2 and CO2 readings with an oxygen analyzer. On day 14, I took out the hamburgers and rated them on a scale of 1-5 in terms of smell and appearance. Results The percentage of O2 dropped drastically in Bags 1 and 2 over the course of the experiment. Bags 1 and 2 started out with 19.7% and 19.9% O2 respectively. Over time, the O2 dropped all the way down to zero. Since Bag 3 was flushed with CO2, almost all the O2 inside it was removed. Shortly after day 1, the level of O2 dropped and remained at 0%. Bag 4 was also flushed with CO2 and nearly all the O2 was removed. The O2 in Bag 4 slowly rose until days 12-14 when a major spike occurred. A leak was suspected. The percentage of CO2 increased in Bags 1 and 2 over the course of the experiment. Bag 3 remained constant with a 100% CO2 environment throughout the experiment. In Bag 4, CO2 started at 100%. It steadily dropped until days 12-14 when a major decrease occurred. Again, a leak was likely. The hamburger in Bag 3 had the best appearance and the freshest smell at the end of the experiment while Bag 4 had the worst appearance, and Bag 1 had the worst smell. Conclusions/Discussion Most of my results supported my hypothesis. A high CO2/low O2 environment extends the freshness of and arrests microbial growth on raw hamburger patties. Bag 3 appeared and smelled the freshest because bacteria couldn#t survive in the 100% CO2 environment. Bags 1 and 2 had the most spoilage. Bag 4 was the second freshest, which did not follow my hypothesis, because there was a leak in the bag.

Competition history

• CSEF 2013 Microbiology (General) · Entry J1512

Resources

• CSEF project summary ↗

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