Yes, a full freezer retains more cold when the door is opened. With a half-empty freezer, a lot of cold air will escape whenever the door is opened and more energy is than needed to bring the freezer back down to the right temperature.

Try to freeze small quantities of food at a time, separated out. Once frozen, pack them together closely. Remember to rotate food regularly and label it, or what you lose in wasted food will cancel out what you gain in energy savings.

The quicker a food is frozen, the smaller the ice crystals that will form. Large ice crystals damage the cell walls of food so that when it is thawed, liquid is lost, including soluble nutrients. Meat especially loses so much moisture that it will be dry when cooked if frozen too slowly. This is why many freezers contain a fast-freeze compartment for the initial freezing process.

Thawing, however, should take place as slowly as possible since rapid thawing also leads to a loss of moisture and dry, tasteless food.

If a choice must be made, the food processor is more useful. Food processors are relatively lightweight and most of the functions are intergral to, or built into, the machine. Food mixers tend to be more cumbersome and their attachments take up much more space.

Food processors make light work of laborious tasks such as chopping, grating and slicing, and some machines also have juice extractors. They make excellent pastry, provided the ingredients are not processed for too long. They do not whisk egg whites well because they do not incorporate enough air, but some machines have a separate whisking attachment. Care needs to be exercised with some models when mincing raw meat so that it is minced, not pulped to mush.

Mixers are usually larger and are good for lengthy beating or kneading bread with the dough hook.