Thursday 26 July 2018

microbiology - Food safety during roadtrips



I will be moving across the country in the coming weeks, and I have realised that I will likely have leftover perishable food in my apartment before I leave and I was thinking of trying to prepare some of it the night before I leave to bring with me. The trip will take me four days, and I was going to cook (extra thoroughly) hardboiled eggs, pork, bacon and sausages. I might even add some salt or something. And keep all of my packaging as sanitary as possible, eg. straight from pan/pot to sterile ziplock.


The eggs I'm unsure of because of the protective outer layer that is chemically removed during processing. The pork and bacon, I feel like they will be alright if they're eaten first. And I'm not too worried about the sausages because they've been processed and cooked.


I think a visual and olfactory test of the foods before I eat them would be wise - especially if nearing day 4. But, realistically, if I keep the food out of the sun covered up it will probably stay safe to eat, right? Or is this a bad idea?


I think that the food would definitely be safe to eat up until the end of the second day. But, what about any longer than that? How did people back in the old days travel with food?


Edit: Just to clarify my question. I am not asking about whether or not my apartment is sterile. And I'm not asking about whether or not bacteria can multiply. I'm very well aware of these answers.


I'm looking for a realistic estimate on food longevity - not the food-standards enforced onto food manufacturers or restaurants by the FDA/Health Canada.



Answer




The biggest factor in whether bacteria can grow in food is water bio-availability. Most non-sterile methods of preserving food (note that canning IS sterile) utilize this fact. Over salting while curing, adding lots of sugar, and dehydrating (or freeze-drying) all either remove water or remove the ability of the bacteria to utilize the water and hence grow in that medium.


This is the biggest reason that a hamburger from McDonalds can seem to petrify without devolving into an ugly mess. If the burger and bun and condiments dry out, bacteria can't grow on it. Put that same burger in a ziplock bag with a few drops of water and you will have the nastiest mess possible in a few days.


Honey and jams can remain at room temperature for months or years, even after opening despite being "watery", and this is because there is so much sugar in the solution, that all water tightly bound to the sugar molecules, leaving none for the bacteria to use (Note that some yeasts still can). Similarly, because of lack of water, crackers last for years, while bread spoils.


For your question with eggs and bacon, unless it was a hard-boiled egg that was cooked twice as long to ensure pasteurization throughout the yolk and you left the shell on, I wouldn't risk it after a couple of hours. Bacon, once cooked, very little water activity. Fat doesn't count for bacteria propagation, they need water. I take cooked bacon on camping trips all the time. I also take sharp cheeses with me and they are good for days.


Your other option is cooking beans (with seasoning) or something and dehydrating them in the oven on a cookie sheet before you go. Then you just need to add hot water. I do this for camping as well.


Edit: I didn't mention that high salt solutions (see pickling) function outside this paradigm somewhat, in that you are creating such an isotonic concentration in which bacteria membranes lyse. I also didn't mention methods of pickling like kimchee and sauerkraut that use salt to positively select for species of bacteria (that aren't pathogenic to us) that can tolerate that salt concentration (mainly lactobacillus) as well as some yeasts.


Edit2: With a Source about water activity


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