Does Freezing Kill Bacteria?
RESPONSES BY CINDY ALEMIAN RICE, RS, MSPH

Are hard-boiled eggs a potentially hazardous food? Many people keep them out at room temperature.
Yes, eggs contain Salmonella bacteria, unless they were pasteurized eggs, in which the bacteria are killed to safe levels prior to sale. Boiling an egg does reduce the bacteria to a level that makes it safe to eat. It should be kept refrigerated until use (<41°F) and not allowed to sit in the TDZ for more than 4 hours, to prevent the surviving Salmonella bacteria from multiplying and potentially causing food borne illness.

What is the proper way to clean dining room tables, especially in hospitals?
Dining tables may be contaminated by many substances bacteria and viruses from a person's hands, arms, leftover food and debris on tabletops. One recent study showed that tables in food courts contained the second highest levels of bacteria when compared with other objects, including ATM machine buttons, and even water fountain handles. One can assume that hospital cafeteria tables would be highly contaminated as well, given the higher microorganism levels in a hospital setting combined with multiple persons sharing the same tables.

Staff often clear dirty dishes from tables, then spray the still soiled tables directly with a sanitizer solution, and wipe with the same cloth, without a sanitizing rinse in between, using the same cloth for multiple tables. Basically they spread the microorganisms all over the surface, and repeat the process from table to table in the dining room, spreading contamination as they go.

This is the correct process to clean tables in any foodservice establishment: After clearing dishes from a table, the surface should be cleaned with a mild detergent solution, to remove all food particles and debris from the surface, and then rinsed. Be sure that there is no soap residue left on the tabletop. The sanitizer solution should then be applied, using either a spray bottle or a wiping cloth dipped in a sanitizer solution and left to air dry for 30 seconds. Remember to first test the sanitizer solution for proper strength using paper test strips. The sanitizer will kill the microorganisms to safe levels but must be applied over a clean surface, as grease, dirt and food particles will interfere with the sanitizer's action. Also, wiping cloths should be stored in a fresh sanitizer solution in between uses so they are staying sanitized themselves.

Does freezing kill bacteria?
No, temperatures of 32° or below will cause most bacteria to essentially hibernate, and the bacteria will not grow, with a few exceptions (Listeria monocytogenes has been known to grow at temperatures as low as 28°F.) However, once a potentially hazardous food is removed from the freezer and allowed to stand at higher temperatures, the bacteria "wakes up" and will start to grow again. Similarly, bacteria proliferation slows down when refrigerated at temperatures below 41°F, and will speed up growth when exposed to room temperatures again.

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