refrigeration and diet--8/30/24

30 Aug 2024

refrigeration and diet--8/30/24

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Today's selection--from Frostbite by Nicola Twilley. Refrigeration’s impact on our diet:

"’They're alive!’ insisted Natalia Falagan, an agricultural engineer at Cranfield University, a postgraduate research institution in the British Midlands. Bananas, apples, blueberries, even the humble potato: despite having been picked, they are still living organisms-and how they look and taste when we eventually eat them depends in large part on what and how fast they breathe.

“Falagan led me into her walk-in refrigerator, where we were surrounded by racks of decomposing produce. Potatoes, onions, apples, and blueberries were hooked up to sensors and monitors like critically ill patients in an ICU. Fruits and vegetables continue to respire to the bitter end, she explained, frantically burning through their own internal sugars, acids, and vitamins as a last-ditch substitute for their parent plants' life support, until they either are killed by being eaten or simply collapse and die.

“On our return from an expedition to the supermarket, most of us would hurry to refrigerate meat, fish, and dairy first; as we've seen, with the honorable exception of beer, the first commercial use to which the new technology of refrigeration was applied was to keep animal products cool. But this implied hierarchy of perishability is wrong, Falagan told me: fruits and vegetables are the most liable to decay. This process can't be stopped; it can only be slowed.

“Unfortunately, Falagan's patients are metabolically unique, which means that they all require their own personalized chill-out regime to counteract the stresses of post-harvest life. ‘It's not enough to simply lower the temperature,’ she explained. ‘You have to know what the right temperature is for each commodity, and the beauty’—or challenge— ‘is that that can differ even between different varieties of apples.’

“Refrigeration's antiaging powers often require supplementation through atmospheric engineering. When it's not photosynthesizing, plant matter breathes in oxygen and exhales carbon dioxide, so tweaking the levels of these gases can slow respiration. Much of Falagan's work consists of experiments in which she applies different ‘treatments’ —varying temperatures and ratios of gases, applied according to varying schedules—to Tupperware tubs full of fruits and vegetables, then monitors their reactions in real time. When I visited, coils of plastic tubing connected dozens of containers of potatoes to a gas-mixing board capable of dispensing atmospheric blends; a respirometer took readings of how fast the spuds were breathing at two-minute intervals. ‘With this instrument, we can see how well we've put the potato to sleep, basically,’ Falagan said. ‘Is it happily dreaming, or is it stressed out, tossing and turning?’

An early example of the consumerization of mechanical refrigeration that began in the early 20th century. The refrigerant was sulfur dioxide.

“Such sophistication is a far cry from refrigeration's early days, when entrepreneurial warehousemen prescribed cold as a one-size-fits-all treatment that could keep apples, onions, and berries completely fresh for years on end, stored under the same roof and the same thermal and atmospheric conditions. The results were not appetizing: frostbitten strawberries, onion-scented apples, and sprouting potatoes. Produce refrigeration's great leap forward had to wait until the 1920s, when the need to consume vitamin-rich ‘protective foods’ became the new dietary orthodoxy.

“As we've seen, refrigeration's mass adoption came about in part because nineteenth-century chemists had mistakenly arrived at the conclusion that consuming large quantities of animal protein was essential for health. Sustaining the productivity of urban workers—essential cogs in newly industrialized societies—required an ample supply of meat, butter, eggs, and milk. As a result, in the late 1800s, refrigeration pioneers focused on shipping beef and lamb, while the fresh fruit that European aristocrats had chilled at such expense in their snow wells and icehouses in the 1600s and 1700s was seen as an optional extra. If they ate them at all, city dwellers consumed fruits and vegetables grown nearby, when they were in season; the most delicate and perishable produce, such as strawberries and asparagus, was a frivolous luxury rather than a dietary necessity.

“Although the British navy started to distribute lemon and, later, lime juice to its sailors in 1795, in order to prevent scurvy, the term ‘vitamin’ and the concept that fruits and vegetables might also contain substances that were essential for life—emerged only in the 1910s. Flush with their new nutritional knowledge, chemists had begun to feed livestock rationally engineered ‘purified diets’ that contained the scientifically recommended amount of protein, fats, and carbohydrates, but nothing else—then realized, as their cattle succumbed to debilitating disease and death, that something was clearly missing. Gradually, researchers narrowed in on these substances and named them, arriving at the alphabet of vitamins we know today.

“As these new findings were publicized in the 1920s, produce began to be seen as ‘protective,’ and popular media urged city dwellers to shift their diets from meat and potatoes toward leafy greens and daily salads. ‘Hardly were the results of the laboratory experiments printed than the new heroes ... were taken up with the enthusiasm of a Lindbergh or a Babe Ruth,’ wrote journalist Eunice Fuller Barnard in 1930 in The New York Times Magazine. ‘Lettuce, formerly a vegetable Cinderella, within a decade occupied the center of the grocer's stalls .... Orange and apple drink stands sprang up on countless street corners, and spinach was irrevocably installed in the menu as childhood's major sorrow.’”