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October, 2013

Cold History
By Dennis Linden

Refrigeration is the process of cooling a space or substance below the environmental temperature. Of course, man has “refrigerated” perishables for eons by natural means like ice or cold water streams.

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Imagine life without ice cream, ice cold beer, a year-round supply of fruits and vegetables or a refrigerator full of perishable goodies to raid at midnight. Actually, until about 175 years ago or so, diets in this country were limited to foods that could be preserved by salting, smoking, pickling and drying. There was little use for refrigeration, since the foods it primarily preserved — fresh meat, fish, milk, fruits, and vegetables — did not play as important a role in the North American diet as they do today. In fact, until the 1830s, when commercial systems using ice as a coolant were developed, the typical diet in this country was mostly bread and salted meats, maybe washed down with some room temperature home-brewed cider. Any fresh fruits and vegetables on the table appeared only seasonally from summertime gardens; the rest of the year produce was limited to root cellar fare.

Refrigeration is the process of cooling a space or substance below the environmental temperature. Of course, man has “refrigerated” perishables for eons by natural means like ice or cold water streams. Ice cellars have been found in China dating back thousands of years. Those in northern climates used freezing outside temperatures and snow to store foodstuffs. In the 1600s, that desire for a “cold one” probably helped spur the development of the first artificial coolant. In the Mediterranean, where the warm climate created a consumer demand for cold drinks, long-necked bottles of juices and liquors were rotated in water mixed with saltpeter to produce very low temperatures and even a bit of ice.

In this country, ice was harvested from a lake near New York City and shipped commercially for the first time to Charleston, South Carolina in the summer 1799. Unfortunately, with just a tarp and no insulation, the delivery was a dismal failure as there wasn’t much of the shipment left when it arrived. Sounds like it was also the first “duh” moment! However, the many innovations created over the next forty years by two Boston businessmen, Frederick Tudor and Nathaniel Wyeth, transformed the selling of ice from a strictly neighborhood business into an interstate industry. Tudor developed insulating materials to build ice houses, which alone cut the normal 66% shrinkage of the day to less than 8%. Wyeth devised a method of efficiently cutting uniform blocks of ice that revolutionized ice harvesting, also resulting in much less product loss as well.

By the 1830s a dramatic growth in city populations had begun in this country. This shift in demographics from mostly rural to more densely populated metropolitan hubs brought with it an increase in income by the general public living in those cities. With this new economic power came a consumer demand for higher quality, fresher foods, especially fresh produce. Of course, as cities grew, so did the distance between the consumer and those rural areas where most fresh foods were produced. Necessity being the mother of invention, Tudor and Wyeth were merely responding to the need to extend the shelf-life of ice in order to support this change in the American diet.

In 1867, cold technology took another leap with the first refrigerated railroad car. The insulated car had ice bunkers at each end. Air came in at the top through vents, passed through the bunkers and then circulated throughout the car. Consequently, the first shipment of fresh fruit tested this system that same year. A shipment of fresh strawberries were packed into large chests that each contained 100 lbs. of ice and 200 quarts of berries. These chests were then loaded into one these new ice-bunker cars on the Illinois Central Railroad and delivered in good condition.

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However, ice as a refrigeration agent eventually became a health issue as sources of clean ice became harder and harder to find, especially around metropolitan areas. By the 1890s, natural ice was often tainted by pollution and sewage dumping. Again, necessity drove invention as improved technology provided the solution with mechanically manufactured ice, which totally changed the definition of refrigeration.

The brewery industry, with its deep financial resources, was the first to jump on this new artificial cold. Refrigeration enabled breweries to make a uniform product year-round. By 1891, nearly every brewery in the country was equipped with primitive but effective ammonia absorption refrigerating machines. Once the more efficient and less costly ammonia compression refrigerator system was perfected, Chicago meat-packers jumped off the ice wagon, so to speak, and were completely mechanized by 1914. I will spare the reader the details of why a compression refrigeration system is more efficient than ammonia vapor absorption—it just is.

By the way, all these improvements in refrigeration technology were utilized for commercial endeavors almost exclusively. While much of large industry operated on mechanical refrigeration, the general public continued to get ice deliveries. The “ice box” and the door-to-door ice-wagon that supplied those boxes were very much a part of the American household right through WWI. As of 1920 only about 5,000 mechanical home refrigerators had been manufactured; a decade later that production had jumped to a million. However, it really was not until after WWII that the home refrigerator became truly commonplace in every American home.

That is, most of large industry had mechanical refrigeration with the exception of the fresh produce business. Trucks with an ice bunker at the front end, as well as bunkered rail cars, ruled the produce distribution pipeline through WWII. For cross country shipments, both modes of transportation required stops at several ice stations along the way to replace the melted blocks and became an industry unto itself. It wasn’t until 1949 that a mobile system made its way into the trucking industry by way of a patented roof-mounted cooling device. Still, because these units were inconsistent and not efficient enough to keep some perishable produce cool, icing stations continued to play a role in produce distribution for another few decades.

As the son of a produce broker father, in the business of shipping and selling fresh Florida corn to wholesalers and retailers in Los Angeles in the late 1950s & early ’60s, these ice stations were a part of my childhood. If a truck driver called in as he travelled across the country when my father was out, I had been trained at a very young age to get the driver’s location and to ask how many ice receipts he had accumulated so far. While these trucks did have refrigeration units, the entire load was also topped with a layer of crushed ice covering the length of the truck. When packed tightly together, even in wooden crates with lots of ventilation, corn generated its own internal heat, causing it to taste starchy. So these early refer units were set at 36° purposely to cause the ice to melt down through the corn to keep it cool enroute. It was critical that the melting ice be replenished regularly during the trip across country.

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Today, refrigeration in the produce industry has been perfected to a science. As a wholesaler, handling many kinds of perishable produce, Melissa’s warehouse facilities include nine separate refrigerated walk-in coolers. The “boxes” range from 32° “wet” rooms for vegetables requiring cold and high humidity to rooms maintained at 45° or above for cold-sensitive tropical fruits and very dry cold rooms for fruits like apples or pears. All these rooms are adjusted seasonally to accommodate the ever-changing array of diverse perishables from around the globe that Melissa’s distributes throughout the year.

The apple and pear industries are totally dependent upon computerized refrigeration systems for profitability. These systems monitor and adjust the temperature of huge storage rooms of fruit that are sometimes sealed away from human contact for as long as eight months. Without this extended storage ability, the entire U.S. harvest of apples and pears would have to be sold between September and December, which would be economically impractical.

The uniform color of retail banana displays are the result of a very technical process within the already complex science of refrigeration. Most bananas arrive in this country still green in refrigerated containers that must be maintained at 56-58°, no more/no less. The fruit is then “ripened” to order using an industry-established 1-7 shade range chart of greenish-yellow to yellow. This controlled uniformity is done by placing bananas in large ripening rooms and then playing with the amount of ethylene gas that the fruit is exposed to using specific combinations of temperature, humidity and length of time in those rooms.

Modern refrigerated transportation also makes it possible to enjoy a midnight snack in December of Chilean raspberries ‘n cream! The days of ice bunkers, ice boxes or a kid asking a truck driver for a count of stops for ice are long gone. Well, almost…while waterproof cardboard cartons have replaced those bulky wooden crates of corn, shippers still spray ice into each carton of corn for a slow melt in route to market. So, even after some 175 years of refrigeration technology, sometimes the best solution is still the “cold water stream” theory!