Vacuum-packagers and food safety

-- Last Updated: Dec-26-07 10:25 PM EST --

I'm a bit concerned with a few things I've read about paddlers vacuum-packing foods for paddling/camping trips.

Most vacuum-packaged foods should be refrigerated or frozen. The packaging film used with these is generally impermeable to oxygen and moisture. Thus, it works great to prevent freezer burn and slow down oxygen-dependent enzymatic reactions that can slowly lessen the quality of frozen foods. In many refrigerated foods such as certain cheeses, vacuum-packaging can slow mold growth and increase the shelf-life.

HOWEVER, under certain conditions, the lack of oxygen in these packages can also allow the growth of some nasty anaerobic bacteria that cause food poisoning. One of these is the bacterium that causes botulism. Many of these bacteria are present in foods in a dormant form (endospore) that is highly resistant to heat, so it doesn't matter if the food is cooked. Many of these bacteria can grow, if all of the conditions are right, in a wide variety of foods, including fresh veggies, some fruits, meats, etc. I work with most of these bacteria, and have been able to get many of them to grow in foods under surprising conditions.

So, don't assume that vacuum packaging foods means that you can keep them unrefrigerated. Frozen is generally better. MOST home fridges, even new ones, run warmer than 40°F ("proper refrigeration temp"), so don't even store them in the fridge for too long (week or so with a few exceptions). Coolers are rarely cold enough.

Believe me, you don't want to be sidelined, or worse, from food poisoning caused by one of these bacteria. A couple of days of vomiting and/or diarrhea sucks, especially if you're in the middle of a week-long paddling trip. Botulism REALLY sucks!

what are the certain conditions?
I dehydrate everything, vacuum bag it over the winter. Into the freezer it goes until trip time.

Trips are from one to six weeks. Never had a problem. All food is cooked before dehydrating.

Are the certain conditions moisture? When you bring a bag out of the freezer to the ambient temp there will be condensation. Its important to have all bags dry before packed and inspect for holes. If torn/holed, out it goes. All food is in single meal packets. I never reseal once opened.

dehydrated food OK
Good point. My concerns are with perishable non-dehydrated foods, such as fresh vegetables, fresh fruit, soft cheeses, meats, starches, etc.

There has been at least one recent post mentioning vacuum-packing of fresh veggies and fruit prior to taking on a paddling trip. Also, I know through my experience handling consumer questions that some people think that it’s OK to vacuum package foods and store at room temp as long as the foods have been cooked. As I mentioned in the original post (hopefully coherently–it’s past my usual bedtime), these are not safe food practices.

Bacteria need available water to grow. Although the amount varies between types of bacteria, the kinds of bacteria that cause food poisoning will not grow in foods that are adequately dehydrated.

So, vacuum packaging is great for dehydrated foods that need to be stored in the freezer before use. The impermeable packaging film will prevent things that cause quality issues, such as freezer burn and exidative enzymatic reations.

Thus, adequately dehydrated foods are a great choice for extended paddling trips!

"certain conditions"
Although there are a lot of predictive models and published food microbiology research about growth of pathogenic (i.e. disease-causing) bacteria in foods, it’s impossible to exactly predict the odds that a particular food can be the cause of food poisoning.

Certainly holding temp is critical, but factors such as food formulations, packaging, and presence of antimicrobial agents (including salt), etc., are also important.

Basically it’s a crapshoot in many ways, but adherence to simple food safety practices greatly decreases your risks of food poisoning. Vomiting & diarrhea are unpleasant, but there are other forms of bacterial food poisoning that have the potential to cause chronic health issues (such as autoimmune disorders). In addition, there can be serious life-threatening forms of food poisoning, such as botulism. In particular, vacuum-packaging of perishable foods followed by holding at ambient temps or inadequate refrigeration, can potentially lead to growth of the bacterium that causes botulism.

It’s kinda like not wearing a PFD. The odds that it you will run into serious trouble without one are low, but for a small percentage of people under certain conditions, it can lead to a huge problem (forgive me, Richard).

Yeah, I’m a food safety geek, and enough of the lecturing. Time for bed!

Never dehydrate & vacuum seal
Beanee Weenees

you probably wouldn’t have to worry
about botulism (etc.) so much if you didn’t have poo in your user-name

the only thing I vacuum pack
are pencil flares

That is kind of funny, although the bacterium that causes botulism is found in soil and marine habitats but is NOT related to fecal contamination.

I hear they’re tasty with ketchup

That’s good to know