Those look like they are done in tubes with an impulse sealer.
You do something similar with bags and a less expensive sealer (about $80) They are only single seals. Sealers with multiple seals are much more expensive.
check out papermart.com or google for impulse sealers Be certain to purchase bags intended for food.
Those are cello bags sealed with a crimper sealer:
You can also heat seal with your regular iron if you get the bags with the seal down the back. I've done it, but you don't get the multiple seals, obviously.