Kenji Lopez, culinary director of the site "Serious Eats" demonstrated a technique for cleverly put food easily without vacuum packaging machine. It uses a zipped pouch that he gently immersed in a tank of cold water leaving a small opening. The air leaves the bag when it is immersed in water, then he completely close the bag, taking care that the water does not infiltrate to the inside. Cheap and fast solution to seal food air free !