Line the inside of the box with foam boards or layers of aluminum foil to help insulate it. Fill sealable plastic bags or water bottles with water and freeze them overnight to make ice packs. You can also use a bag of ice cubes. Place your DIY ice packs or ice cubes at the bottom and around the sides of the box.
Underground coldrooms were used. Pond or river ice was cut in blocks and buried in sawdust, corn husks, etc., in the cold room. Food could be stored for some time there. Houses could be equipped with ice boxes that looked a bit like refrigerators.
Simply put, cooling preserves certain foods so they last longer. Most folks who unplug their refrigerators have a backup system or plan in place, such as a zeer pot. Many use a small cooler, or perhaps a mini-fridge or a small freezer to store very small quantities of items like milk or meat.
Freezer units are used in households and in industry and commerce. Food stored at or below −18 °C (0 °F) is safe indefinitely. Most household freezers maintain temperatures from −23 to −18 °C (−9 to 0 °F), although some freezer-only units can achieve −34 °C (−29 °F) and lower.
Just gather some ceramic pots, sand, and water, and you've got a portable, non-electric DIY mini-fridge with a time-tested design. After all, people were preserving food for thousands of years before you had to keep that leftover takeout from stinking up your college dorm.
An ice chest packed with ice or snow can keep food cold. Bags of ice or block ice can be purchased and placed in the refrigerator to keep food cold. Dry ice from a local ice company or grocery store can help save frozen food.
Ice houses on lakes and rivers were effective ways to keep food cool before the invention of electricity. If ice or snow wasn't an option, underwater or underground storage, like cold cellars, provided refrigeration.
Wrap the container in a towel.
Once your ice is in a bucket or a cooler, wrap it up in several towels or blankets. The fabric helps keep the chilly air from escaping the container, ensuring the ice stays frozen for longer.
At the end of the 19th century, many people kept their food fresh in iceboxes made of wood. These cabinets held large blocks of ice to keep food cool. Iceboxes were lined with tin or zinc for insulation. Ice delivery businesses grew as more homes required ice to preserve food.
Food would be smoked, dried, salted, fermented or pickled. It would also be kept in root cellars or pits underground. Wealthy people who lived in cold climates were more likely to have an ice pit or later an ice house where they would keep ice for use in warm months.
A cooler or Esky is the obvious choice, or if you're an outdoor enthusiast with a portable camping fridge that can operate without mains power then you're home and hosed. With your fridge out of action you need an alternative place to keep your food cold. But you can also use your freezer.
Into the 1930s, households used large blocks of ice to keep food cold in "iceboxes." This photo is from the 1920s. Courtesy of the Sloane Collection. By the end of the 1800s, many American households stored their perishable food in an insulated "icebox" that was usually made of wood and lined with tin or zinc.
For millennia, those rich enough got servants to gather snow and ice formed during the winter and stored it in straw-lined underground pits called 'ice houses'. But the ancient Persians stumbled across a neat bit of physics that allowed them to create ice from water even during the summer.
Group food together in the freezer. This helps the food stay cold longer. Have coolers on hand to keep refrigerated food cold if the power will be out for more than 4 hours. Purchase or make ice cubes in advance, and freeze gel packs ahead of time.
If lunch contains perishable food items, be sure to pack with at least two cold sources! Ice packs & frozen juice or water works great!