You may have seen vacuum food sealers advertised on television or seen one at a store. These devices remove excess air from packaged items, such as cereal and frozen vegetables, extending the food's shelf life. It is also possible to vacuum-seal powdery substances, such as dry milk and hot cocoa mixes, if you use the right containers and techniques.
You can buy electric-powered food sealers in stores or online, or choose a hand-pumped food sealer. Use a damp cloth to remove drink powder from the surfaces to be sealed because stray powder will prevent a complete seal. Avoid allowing any drink powder to be sucked into the vacuum sealer, because it will damage the machine.
Glass canning jars can sometimes be used for vacuum sealing powdery substances like drink mixes. The vacuum sealer may need a special accessory to seal jars. A short plastic hose attaches to the vacuum sealer and connects to the jar sealer accessory. Select a jar sealer that fits the jar you're using. They are available in either regular or wide-mouth sizes and are usually sold separately. Put the drink mix in the jar, place a hot canning jar lid on its rim, secure the jar sealer to the top of the jar, then turn on the vacuum sealer.
Special plastic bags intended for use with a food sealer are another option. They take up less room than glass jars but have the disadvantage of being semi-permeable. Whatever is stored in them may take on the flavor of other foods stored near them. Vacuum sealed drink mixes in plastic bags have the advantage of saving space. Place the powdered drink mix in the bag, wipe any residue from the edges of the bag to be sealed and hold the bag's edges together tightly to avoid the powder's being sucked into the sealer. Label and date all containers of drink mix, so you can track them and use the oldest first.
Place a paper coffee filter or a paper towel on top of the drink mix to prevent any powder being sucked into the sealer. Use glass jars intended for canning because they have been designed to stand up to more pressure than jars that held store-bought foods such as mayonnaise or spaghetti sauce. Some food sealer manufacturers also sell plastic canisters designed for vacuum sealing.