6 replies to this topic

[Jpainter]

Hello all, 

 

A quick background. Our company produces fully cooked vegetable products going into a sealed plastic bag for packaging. This product is chilled on site (maximum 55F), but is shipped 1 hour on a reefer truck to go through a full blast freeze. We have recently had issues of product bags getting very bloated with excess air. I believe that our issue is just getting excessive air in the package to begin with, then after sitting in a blast freezer where air temperature is -50F the air is simply warming back up and expanding (bloating) air in the bags. However, other members of the food safety team believe this could stem from microbiological activity within the product releasing CO2 and expanding packages. I don't believe this is the case, as product is not bloated at arrival at the blast freezing facility, and time isn't sufficient in the 5 hours from packaging to being fully frozen to bloat packages so severely. Has anyone else faced this problem of sealed plastic bag type packages bloating or inflating upon temperature change? What are some strategies to avoid this? We are currently destroying any product that is bloated on the off change that it is caused by a microbiological issue. 

 

 

-Jpainter

[zanorias]

Hi Jpainter,

 

Micro seems the likely cause of bloating though it is curious considering the temperatures and time as you said. Have you sent any affected product to be tested? Would be worthwhile I think just to check or potentially rule out. I had a similar issue recently with a vegetable sauce product that we deposited hot into pouches and sealed, then was bloating after it had cooled down. Micro samples came back negative. We found that decreasing the cool time helped and it hasn't been an issue since, though the exact cause I'm still unsure as the original cooling time and lab certs suggest it wasn't micro

[Scampi]

Definitely not micro in this time span and not these temperatures, 5 hours at 35C, for sure, but not at your temps.  Are the veg pre chilled or packaged when hot and then cooled?

 

https://education.se...d-air-5102.html

 

Are you gas flushing the bags and then vacuuming out the excess at all? 

 

Gases will all do some weird things when exposed to vast temp changes. Also, check your levels, if this just started you could have a valve that isn't working correctly and letting in too little or too much

[Jpainter]

Zanorias- We have sent product off for micro testing. Results all came back negative, with a coliform count of 100 CFU/g

 

Scampi- Everything is prechilled before packaging to about 50F. We are not flushing bags, as we don't have the equipment or budget to do so right now. 

[Scampi]

You could try a line of micro perforations along one edge of the bag to see if that helps. The frozen veg poly bags are all perforated, one would think this is why. Which would also explain why frozen veg all have ice crystals on them

 

The other culprit could be the bags themselves..........has the packaging company made any changes what soever to the product you are using?

[QAGB]

You could try a line of micro perforations along one edge of the bag to see if that helps. The frozen veg poly bags are all perforated, one would think this is why. Which would also explain why frozen veg all have ice crystals on them

 

The other culprit could be the bags themselves..........has the packaging company made any changes what soever to the product you are using?

 

Scampi has a great point. Some packaging companies will change packaging without notification, and better yet, tell you they didn't make any changes. Obviously there are great suppliers out there, but there are some that will do just as mentioned. If you have some product retained from before the bloating issue happened, you could do some testing on the packaging material itself and compare to the product packaging in question to see if there is any noticeable difference (weight or otherwise).

[Jpainter]

I didn't even think about an unnoticed change in packaging. Great advice! I have thought about the micro perforations, because we pack a diced vegetable it is not feasible for water retention of the two year shelf life. I think our issue stems in our 3rd party blast freezing company. They have a history of letting frozen items sit on the non-refrigerated dock for extended periods of time. I believe the huge temperature swing from -50F to 80F room caused some thermal shock resulting in gas expansion.