For meat or fish intended for long term storage should be pre frozen before it can be vacuum sealed. However, uneven freezing can lead to purge of juices and therefore make the meat or sea food lose it’s identity and flavor. Instead, opt for short-term freezing by packing the constituents in a freezer bag or flash freezing by spreading small pieces of meat evenly on a large wax paper, covering them with ice and freezing the same for a day or two.