Pot Roast Air Expanded bag at hour 36

[slfrinell]

I am currently doing a 48 hour chuck roast. Cooked @ 133.

It is a pre-seared 3lb chuck roast vacuum sealed in a food saver bag.

There was a brief flip of my circuit breaker which was quickly remedied around hour 16.

This morning I woke up and came down stairs the bag is full of air and floating. I had magnets holding it in place so it wouldn’t crowd the sous vide. These were all on the bottom of the pan.

So I took it out and cut it open to reseal it. As my daughter puts it, “It smells like throw up!” Obviously I am throwing it out, but I was wondering if anyone knew what happened. I’ve never had this much air fill a bag. Especially at hour 36.

I’ve really looked forward to this pot roast. The last one I did for 24 hours and it was as good as prime rib.

Thanks,
Shawna Frinell

[Mirozen]

My guess is that you are the victim of “autolysis”.

The best answer/description I’ve seen posted in this forum regarding this problem was provided by @Ember. This is a link to the thread for the full conversation: Another 54C gem... Beef cheeks - #31 by Ember

Below is a quote taken from that conversation…

@Ember

Bacterial bloom is also given as the cause of loss of meat during a long cook. The meat when released from the bag has an ‘off’ smell. Once again, the cause of this is not bacterial. The bacteria is rendered inactive long before it can create enough of a bloom to ‘turn’ the meat. What is actually happening is loss of product due to autolysis. This is the same natural process we make use of when aging meat. Enzymes contained within the meat commence the breaking down the meat. This process starts when the animal is dead. It is slowed by refrigeration, but not halted. At ambient temperatures, even in a 100% sterile environment, meat will ‘go off.’ At the temperatures used for sous vide cooking the process is sped up. Cooking low temps and long times is a balancing act to get the temperature low enough to produce desired results while cooking fast enough to beat the natural process of autolysis.

Autolysis is also the reason why pasteurised food will not last indefinitely under refrigeration. Pasteurisation and refrigeration have rendered bacteria within the product dead or inactive but the product can still go off over time. Autolysis is the reason why.

[Ember]

Yup. @Mirozen is right. Autolysis is the reason. Unfortunately it is the risk of the low and slow cook. You’ve got to weigh up the risk versus the reward. For me the reward is worth the occasional disappointment. Or you can cook at higher temperatures, but still within the doneness zone of what you’re after.