The Challenge of Keeping Food Fresh and Edible
Advances in technology can have a profound impact on the world and change the way we live.
Keeping perishable foods has always been a problem.
Foods with a high water, sugar or protein content form an excellent culture medium for fungi and bacteria that are widespread in the environment. Microorganisms, either present on the food since production or carried to it as air-borne spores, begin growth on exposed surfaces.
Microorganisms multiply rapidly at room temperatures, using the food as a source of energy and fouling it with metabolic by-products. This results in the appearance of visible colonies (mood, bacterial spots) and decomposition of the food. Decomposing food is degraded in odour, texture and taste and may even harbour poisonous compounds.
For millennia, perishable foods had to be consumed quickly, before decomposition occurred. As a result, things such as milk, cream, meat, fish, fresh fruit and vegetables could not be stored for long or transported over great distances.
Staple foods in the human diet, those available year round, were restricted to non-perishable grains, vegetables and dried or cured meats and smoked fish.
Fresh fruit, meats, fish and vegetables are the most difficult to protect against the microorganisms of decay.
In winter, perishable foods could be kept outside, on the windowsill.
Winter provides ways to keep food cold naturally.
In countries with a cold winter climate, it was soon discovered that when perishable foods were kept at low temperatures, the process of decomposition was substantially slowed. This is because at lower temperatures the growth of microorganisms is significantly retarded.
In winter, perishable foods can be kept fresh (free from decomposition) for days at a time by storage in protected areas (like a cold cellar) or on a snowy windowsill. Pioneer families sometimes kept perishable food in a water proof container submerged in the cold water of a fast-flowing stream.
The use of natural, winter-cooled food storage is inconvenient, of course, and unreliable because of the danger of an unexpected thaw.
The Ice Box: Using Ice to Keep Food Fresh
The ice box was a simple device, like a large ice cooler.
Winter cold could be brought indoors by putting a block of ice into an insulated box.
The ice absorbed heat from the food to keep it cold and free from decomposition. The insulated sides of the box prevented warm air in the room from rapidly melting the ice.
The ice box, an early kitchen appliance that used blocks of melting ice to keep food cold.
Using large saws to cut ice on a lake in winter.
Harvesting Winter Ice
Ice harvested in winter could be saved to cool food in summer.
In Canada, there was always plenty of natural ice in winter. By the early twentieth century the demand for ice to keep food fresh in Canadian homes was so great, it had fostered an ice harvesting industry.
Each winter, after waiting for the ice to become thick enough, horse drawn wagons were driven out onto frozen lakes. Large saws were used to cut out great blocks of ice that were hoisted onto the wagons.
The harvested ice was dragged back onto land and warehoused. Smaller blocks were cut and delivered to homes throughout Canadian cities, towns and rural areas. Thousands of men were employed in this activity, and if an unusually warm winter limited the supply of ice, the resulting unemployment constituted a real economic problem.
Keeping Winter’s Ice Through the Summer
Ice blocks were buried in sawdust to provide insulation against summer heat.
The problem with ice harvested in winter, of course, was how it could be used to keep food fresh in Canadian homes during the summer. Before the advent of mechanical refrigeration, the only way to do this was to stockpile large quantities of winter harvested ice in insulated storage rooms.
One of the best insulating materials that was available inexpensively a hundred years ago was sawdust. Produced in quantity as a by-product of the Canadian forestry and lumber industry, sawdust was commonly used to insulate summer stores of winter-harvested ice.
Ice blocks were stacked in large piles in warehouses, and the ice piles were then buried in a thick layer of sawdust. During the summer, as stored ice was needed to supply the domestic market, workmen dug into the sawdust piles and retrieved the valuable commodity preserved within.
Of course, some melting did take place, but the combination of large ice stockpiles and good insulation insured that winter ice would remain available right through until the following winter season allowed replenishment of the supply from nature.
The whole process could also be replicated on a smaller scale. Farms producing perishable foods often had their own small ice houses to keep ice through the summer for their own consumption. On dairy farms, for instance, milk cans were kept in a tank filled with iced water.
A country ice house, with a pile of insulating sawdust in front.
Horse-drawn delivery van bringing blocks of ice to private homes.
[Archives of Ontario]
The Iceman Cometh
Before refrigerators, many households ordered ice delivery several times a week.
Ice storage and supply companies drew on their warehouses of insulated winter ice to supply the domestic market. From central distribution depots, horse-drawn vans were sent out daily on extensive rural, town and city distribution routes. The horses proceeded from home to home, often having memorized the whole route that they followed each day.
If the household had a sign in the window indicating that ice was needed, the deliveryman used a large pair of ice tongs to hoist a block of ice onto his back.
On the way into the house, his back was protected from ice melt water by a leather apron. The ice was taken right into the kitchen where the housewife, usually at home in those days, gladly opened the door of the ice box so the new block could be placed inside.
The Trouble With Ice Boxes
Ice boxes were messy and not very efficient at keeping food cold.
When ice was first delivered, it cooled the food storage chamber well, although temperatures were never lower than several degrees above freezing right beside the ice block. Closer to the walls of the cabinet, temperatures were still higher.
Over the next day or two, heat absorbed from food and the walls of the container slowly melted the ice block. As the block got smaller and smaller, the temperature inside the food storage chamber slowly began to rise. As a result, food storage temperatures fluctuated from day to day.
The processes of ice melting and food warming up were speeded up enormously, of course, every time the ice box door was opened to take food out or put new food in.
Water from the melting ice trickled down through a tube leading from the ice rack to the bottom of the ice box. The melt water pan that stood on the floor under the ice box had to be emptied once or twice a day. If the household missed carrying out this duty often enough, ice melt water spread across the kitchen floor.
Melt water from this ice box has overflowed the collecting pan, creating a puddle on the floor.
An “Ice Today” sign signalled the deliveryman that more ice was needed in the home.
[Archives of Ontario]
Living With an Ice Box
The ice box seemed to need constant attention.
Emptying water and a sign that said “Ice Today” were characteristic of a home with an ice box.
The ice box, as a result, was a household appliance that required a good deal of daily attention from the householder. One had to keep a constant eye on the size of the ice block, for if the block were to disappear altogether, especially during summer, temperature inside the chamber would rise rapidly and the food would spoil.
It was important as well that someone be home to receive ice deliveries. There was no way to leave an ice delivery until the woman of the house arrived home in the evening.
Women, who as the traditional homemakers already had many labour-intensive tasks in the kitchen, also had to be at home to be sure the ice delivery was received.
The Arrival of Mechanical Refrigeration
Artificial cooling brought new control to food storage.
As the technology improved, mechanical refrigeration units became small enough for commercial food-handling operations like dairying and meat packing. But they still required a lot of space.
The benefits of mechanical refrigeration for the safe handling, storage and shipment of perishable foods meant an increasing demand. Never before could temperatures be held so low and with such consistency and reliability.