Hello,
in my company we have started packing sunflower seeds using MAP and the problem we have that in some of the packages during storage a vacuum forms. We use a vertical packaging machine and 100% nitrogen gasses. Can someone advise me why is this happening?
Do you mean they lose gasses?
I guess some of packs can not be sealed hermetically. Do you check seals periodically?
Could you share some photos?
I mean the packaging shrinks and tightens around the seeds. During packing there is maybe 5% of oxygen left in individual packages. The packages are sealed correctly, because they are tightly bound around the seeds. We check seals each hour. I took the photo out of internet, but imagine them looking like this after some days 
it is strange, because not all packages become like this 
This means there is no gas in the pack.
1 hour is too late for check, 15-20 minutes is good and of course it depends on your machine speed.
And how do you check seals?
because all packs do not lose gas but some of them do.
But because there forms a vacuum it means that the seals are okay
How do seem your packs which are OK ( MAP, with Gas ) for you?
The photo you shared not a MAP package, it seems a vacuum pack.
No, this is not true. Pack can lose gas in display, box or case ( under pressure ) and it turns a vacuum pack. this does not mean seal is OK.
Yes, the photo is after storage, not during packing. It shows the problem.
Please see this photo, we use nitrogen in this type of packs.
But if the seal would not be okay the vacuum would not hold, no?
It can hold for a few weeks maybe more. Because after packaging proccess there is a pressure in the pack so it easily lose the gas. Also if it is under pressure ( in the box ) this will be easier.
But after lose the gas, air can not enter in the pack easily ( becasue pack in and pack out have same pressure ) so vacuum can be hold.
You can check the gas exist or not with water test as you know.
But if I open the pack the vacuum disappears. That means that the seal is okay
No.
Seal is broken but very very small so air can not enter the pack unless you open it.
Okay, I will try to merge packages in water. Thank you
I have suggested your theory to our production manager, and he says this cannot be the case, because during packing in our packaging machines the nitrogen is injected into packages via a tube, then after a second they are sealed, and because of that time that the pressure in the atmosphere and the packages becomes the same
so your packs are puffy?
they have nitrogen so inside pressure should be bigger then outside and if you put to bags in a box especially pack at the bottom will subjected to pressure and if seal is not pefect it will lose the gas.
The best way to be sure seals are perfect use water.
They are a bit puffy, but soft. I just started working here, so I do not know much about the technology. I will surely merge them in water to check. Thank you again 
Don’t you think it’s possible that the seeds are absorbing some of the gas. Check properly, the treatment given to the seeds before packing and also the properties therein that can cause it to absorb the gas.
Hi @Viktorija Any update .
is the packaging material of this one (curry written plastic material) and your sunflower seeds the same or different (in terms of the thickness, material type etc).
Good to attempt an appropriate ‘control’ packet and see if this is due to any absorbance or moisture effect related to the seeds itself and not related to your MAP itself.
Hello,
sorry for the late reply. I have been doing tests and there seems to not be any correlation. Moisture of the seeds has no effect. We have tried packing without any MAP, with MAP, putting packages in water. The only thing is that if I put vacuumed packs on a radiator the packages expands and after cooling vacuum forms again so it probably has to do something with gas and temperature (with MAP and with no MAP)
hi you sold your problems
