Ive been very succesful at chillin the food down first then vaccum sealing it. Some that I have done, the ones that have more liquid than others, I have froze first inside the bag making it as tight as possible, taking an aligator clip and closing off the bag. After it has gotten to almost that freeze stage I suck it up and seal it. If there is less liquid then I put in the Fridge to cool down first.
Semper Fi.....Chargriller Pro w/SFB, Weber Q 200, OTG 22, SJS, recently became a judge in training.