Cold Chain

July 15, 2013 5:44 PM

"The diet of the average American is almost entirely dependent on the existence of a vast, distributed winter--a seamless network of artificially chilled processing plants, distribution centers, shipping containers, and retail display cases that creates the permanent global summertime of our supermarket aisles." -- The Atlantic
posted by jim in austin (31 comments total)

Keep going past this part:

We didn't get jetpacks, in part, because we were too busy building and refining the "artificial cryosphere," as Twilley calls it.

It recovers.
posted by Etrigan at 5:49 PM on July 15, 2013 [1 favorite]

Cool!
posted by sneebler at 5:56 PM on July 15, 2013 [1 favorite]

Nicola Twilley has an excellent blog, Edible Geography, where she has written about this before.
posted by the man of twists and turns at 6:03 PM on July 15, 2013

A good read is Susanne Freidberg's Fresh, which provides a historical context for the modern obsession with freshness as a virtue. A big part of the modern obsession with fresh fruits and vegetables is the product of intensive marketing, novelty, social status and US-led competitive nationalism.
posted by chrisgregory at 6:18 PM on July 15, 2013 [2 favorites]

I have to say, the modern supermarket is one of capitalism's most genuinely miraculous creations. To get such a mindboggling variety of food and drink, fresh and processed, domestic and international, clean and organized and attractively packaged, and at such relatively low prices, is just awesome. The logistics necessary to accomplish this feat boggle my mind.
posted by shivohum at 6:30 PM on July 15, 2013 [29 favorites]

Is this why the supermarket peaches in San Francisco are so awful, despite being within 100 miles of prime peach growing territory? I'm all for convenient transported foods when they are delicious. But most of the fruit in SF is unripe, sour, flavorless. Even during prime season. Unless I go out of my way to find farmer's market or fruit stand fruit.
posted by Nelson at 6:41 PM on July 15, 2013 [2 favorites]

Is this why the supermarket peaches in San Francisco are so awful

Down in the peninsula all of the fruit is quite excellent at even normal grocers (Safeway, etc.). Might want to change where you are shopping.
posted by rr at 6:59 PM on July 15, 2013

I'm okay with this. In my uber-Green dictatorship, the Cold Chain will be the part of the electric grid that soaks up all the excess power from the 100% renewable generation system.
posted by ocschwar at 7:06 PM on July 15, 2013

That cold chain is also keeping medicines and medical supplies fresh and is a key component of global public health infrastructure. I doubt the two systems overlap much, or at all, but the technology is the same.

Nelson, what supermarkets are you getting fruit from? I just had some of the ripest, juiciest peaches in my life from a San Francisco grocery store (and a farmers' market, which wasn't what I'd call out of the way).
posted by late afternoon dreaming hotel at 7:09 PM on July 15, 2013 [1 favorite]

The article mentions the Tropicana processing center, but not what is (to me) the most interesting part of the cold chain: the transit. Specifically, in the case of Tropicana, the Juice Train, by which mechanism fresh orange juice was eventually provided nationwide:

"In 1970, Tropicana orange juice was shipped in bulk via insulated boxcars in one weekly round-trip from Florida to Kearny, New Jersey. By the following year, the company was operating two 60-car unit trains a week, each carrying around 1 million US gallons (3,800 m3) of juice. On June 7, 1971 the "Great White Juice Train" (the first unit train in the food industry, consisting of 150 100-ton insulated boxcars fabricated in the Alexandria, Virginia shops of Fruit Growers Express) commenced service over the 1,250-mile (2,012-kilometer) route. An additional 100 cars were soon incorporated into the fleet, and small mechanical refrigeration units were installed to keep temperatures constant on hot days. Tropicana saved $40 million in fuel costs alone during the first ten years in operation."

(I learned about the Juice Train from one of the 8 zillion DVDs about trains my preschoolers have, and it was actually really interesting!)

When you start to learn about it, it's AMAZING how much our food infrastructure depends on refrigerated trains and trucks on freight lines and the interstate system. It's basically not possible to have a modern food distribution system without major, modern transit infrastructure. One of the major causes of world hunger is problems with physical distribution -- roads (or rail, or ships, or planes) that get agricultural products from farms to processing centers to distribution centers. The better the roads -- paved, smooth, fast, big -- the more things you can do with trucks: make them faster, more technologically advanced (and delicate), make them bigger. The better the trucks and roads, the less spoilage you have between farm and table. And so on.

I look at the Mississippi River feeder rivers in the fall when the corn is harvested and there's this whole amazing field-to-truck-to-silo-to-train-to-barge system where all the grain runs "downstream" to get to processing plants, and then is turned right around and sent back out on the arteries and arterioles and capillaries of the distribution center until it gets to your supermarket and you, little blood cell person, walk or drive it to your house.
posted by Eyebrows McGee at 8:25 PM on July 15, 2013 [9 favorites]

Several years ago, a coworker asked, in a round-the-watercooler way, what I thought the most important technological invention of the 20th century was. Without even thinking much I said modern refrigeration. I've yet to think of another development in that century that has improved health and quality of life more. And for my money, it is easily top two or three in all of human history behind, say, plumbing and electrical distribution.
posted by OHSnap at 8:42 PM on July 15, 2013 [4 favorites]

"Ice is civilization" was the mad inspiration of the central character in Paul Theroux's The Mosquito Coast.
posted by Mars Saxman at 9:34 PM on July 15, 2013 [6 favorites]

The Juice Train, previously.
posted by pjern at 10:43 PM on July 15, 2013

The Cold Chain is to The Cole Train as Masterchief is to MasterChef
posted by Charlemagne In Sweatpants at 12:33 AM on July 16, 2013

I recall an article in the 80s by a Russian guy who on his first visit to the US visited a grocery store and was shocked by the variety and freshness of the produce. He actually started crying because that's when he realized Communism couldn't compete with Capitalism. So in a sense, Refrigeration helped win the Cold War.
posted by happyroach at 1:20 AM on July 16, 2013 [1 favorite]

There was a time when refrigerated goods in transit were packed in dry ice rather than refrigerator cars. My grandfather gave me an amusing Dry Ice Loading Chart circular slide rule from his days working at the USDA in the 1950s. One side lists pounds of dry ice per hour vs. inches of insulation. The other scale lists temperature difference vs. length of trailer. It appears you'd measure the trailer size and insulation, estimate the highest temps in transit and the duration of the trip, and it would give you the amount of dry ice required to keep it frozen until it arrived.
posted by charlie don't surf at 5:05 AM on July 16, 2013 [1 favorite]

Is this why the supermarket peaches in San Francisco are so awful, despite being within 100 miles of prime peach growing territory?

Try living in Indiana, where you are almost literally surrounded by oceans of corn. Yet, unless some little farmer nearby staked-out an acre to grow sweet corn for his roadside stand, the edible corn we get in the markets are usually trucked-in from places like Florida. Those oceans of corn here in the state are primarily grown for use as feed corn or ethanol production. Probably some corn syrup/HFCS, too.

Thankfully, I hate corn-on-the-cob, so it's no biggie to me. Still, it's a crazy situation.

Tomatoes are the same way here. I live in a part of the state with huge tomato farms, but none of them are raised to be sold fresh. They're harvested for processing at the nearby Red Gold plant. Even at the height of fresh-tomato season, the round lumps in the supermarkets are tasteless hothouse balls.
posted by Thorzdad at 5:16 AM on July 16, 2013

Nelson, what supermarkets are you getting fruit from?

Andronico's, Mollie Stones, Whole Foods; the fancy expensive markets in SF. All selling hard yellow peaches that taste bitter or sour, not sweet and fleshy. The white peaches are generally better tasting but also sold rock hard. I have much better luck with peaches bought from Mexican markets in the Mission, which are also half the price. If the timing works out I do great at the Noe Valley farmer's market, there's a specific stone fruit stand there that's pretty good.

Peaches are just one specific example, particularly topical at the moment. It's not a new story that American supermarkets have sacrificed quality for consistency and availability. And I sure do love my year-round avocados! But there's really no excuse in San Francisco for having bad produce, given how close we live to where half the produce in the US is grown.
posted by Nelson at 8:03 AM on July 16, 2013

Rupee peaches tend to get bruised and look ugly. Expensive supermarkets want to sell perfect LOOKING fruit, which means unripe and nasty. Don't buy fruit at expensive supermarkets, it's never worth it.
posted by aspo at 8:11 AM on July 16, 2013

Nelson, by the fact that you mention that the peaches you're buying are both hard and sour, and not sweet/fleshy, and that you mention that the white ones are sweet but hard, I think there might be a simple fix. I hope this information won't be insultingly obvious. Let me put on my stone fruit hat from my years working at the California Tree Fruit Agreement and give you some background...

I think you're having more success at the farmer's market because the transportation chain is shorter and the fruit can be harvested later and coddled more, and at the Mexican market possibly because they also use a different transportation chain or possibly because they hold their fruit aside to allow it to soften. Some stores do that holding aside, some stores don't.

In terms of harvesting peaches, it has to be done when they're "mature," meaning that the fruit is fully filled out and has gained the proper amount of sugar, but if they're going via the slightly longer supply chain to a supermarket and not straight to a farm stand or farmer's market, it also has to be done before they fully soften, because the process of packing them in boxes and transporting them will bruise them, and by the time they get to the store, they'll have gone from perfectly ripe to overripe.

So growers test for the presence of sufficient sugar and gauge fruit firmness with something called a penetrometer, which measures how many pounds of pressure it takes to pierce the fruit. They then figure how much the variety they're harvesting will soften at the temperature the fruit can be expected to be stored at (warmer temperatures generally lead to faster ripening) for the amount of time that can be expected to elapse before it's sold, so that the fruit won't be extremely overripe or extremely underripe when it gets to the display.

Now back to your hard, sour fruit. There are a number of changes that take place in stone fruit as it is going from mature to fully ripe. Green color, acid level, insoluble pectins, and firmness drop. Yellow color, flavor and aroma compounds, and soluble pectins rise. Ethylene (the fruit's natural ripening gas) output rises for a while but then levels off. The level of sugar the fruit contains and its red color stay exactly the same. The effect of all these changes is that the fruit goes from hard and sour to soft and sweet. The fruit doesn't actually get any sweeter - as I said, the sugar level stays the same - but it tastes sweeter because we're able to taste the same amount of sugar better as the acid level drops.

Notice that you said that that the white peaches you buy are also hard - but they're sweet as compared to the yellow ones. That's because most white peaches are what are known as "sub-acid," meaning they have a much lower acid level than the yellow varieties do, so they taste sweet even when they're quite firm. They don't need to have their acid level drop in order for their sweetness to be perceptible.

So if the problem is that the fruit you're buying is mature but not fully ripe - and as a former Whole Foods team member as well, I know that their stone fruit is generally of very good quality, and we certainly get good stone fruit from them even here out East - there's a very simple solution. And that is a brown paper bag. When you bring your very firm supermarket stone fruit home, pop it in a bag on the counter, which will hold in just the right amount of ethylene gas. A plastic bag holds in too much, and will lead to the fruit becoming bitter and possibly rotting prematurely. Check the fruit every day, twice a day if it's white flesh, because they "move" faster as they ripen. When it's at the degree of softness you like it, move it into the fridge, where it will stay at that ripeness for several days.

Never put firm stone fruit in the fridge, because refrigerator temperatures can cause it to get mealy inside, and then it'll never ripen properly. (If stone fruit has undergone special post-harvest temperature handling called pre-conditioning, it can be safely put in the fridge, but there's no way to know by looking at it whether it has or not - better safe than sorry.)

There is the possibility that you are getting immature fruit sometimes. The best way to tell that is to look at the stem cavity, where the fruit was attached to the tree. In yellow-fleshed fruit, the area that's not red should be a bright golden yellow, and in white-fleshed fruit a creamy yellow. It should not look greenish. If so, it's immature and will never ripen properly. That's much more common at the beginning of the season (before Memorial Day) than now, at its height.

I hope that helps you get better-tasting stone fruit wherever you shop.
posted by jocelmeow at 2:44 PM on July 16, 2013 [261 favorites]

Thanks for the detailed comment, jocelmeow! I certainly have tried holding my fruit to let it ripen myself, but with my luck with peaches mostly they just get mealy or moldy. But I haven't been religious about putting them in a paper bag like my momma taught me, I'll give it a try! Also great to get all the detailed info on how peaches are picked and ripen.

Are grocery store peaches in California typically refrigerated between the time they're picked and the time they're put on sale at the store?

(Off to go eat some delicious Rainier Cherries. For some reason those do well in grocery stores.)
posted by Nelson at 3:06 PM on July 16, 2013 [1 favorite]

In re the paper bag thing -- should the bag be open, closed, folded shut, tightly clamped shut...?
posted by Etrigan at 3:08 PM on July 16, 2013

Etrigan, just fold the top over a couple times and you're all set.

Sure thing, Nelson. Optimal handling: stone fruit is transported with the other reefer stuff in the cold chain, very cold, just above freezing. Once it gets to the store, it can stay stored at that temp, or be brought up to room temp to ripen. The trouble is that middle range - if stone fruit is kept at a typical home refrigerator temp and hasn't been pre-conditioned, it'll turn mealy. If pre-conditioned, no problem with that.

Typical handling - well, it may not be optimal! My organization worked to provide retailers with information on handling, which we knew was needed based on surveying store-level employees. It was an uphill battle getting that specialized knowledge delivered. It's just one of hundreds of produce items. Some retailers are great about little details, some aren't. Our spring meeting was addressed one year by an executive from Wegman's, who said that peaches were the single most difficult item in the whole store to get right.

One thing I would compare it to is bananas - there's massive infrastructure devoted to bananas, and people know not to put bananas in the fridge to ripen. The reason they know that is the long-ago Chiquita Banana campaign is still paying dividends. Good stone fruit handling is pretty similar for the consumer, but it never had a campaign that got into the popular imagination like that (read: $$$$).

Another comparison: Stone fruit is unlike apples, which are harvested once a year and stored in controlled atmosphere for months. You probably have noticed that stone fruit is not usually sold by variety. That's because each stone fruit variety is harvested with two, three, or more passes in an orchard over a week to ten days, and then must be sold basically immediately. There are upwards of 200 varieties each of peaches, plums, and nectarines grown in California. Too many signs to make!

Your Mexican market that's doing a good job with their stone fruit - what they are probably doing is a larger version of the paper bag trick, managing their supply so they have some of each fruit at each stage of ripeness - receiving it when it is still firm, setting it in a room-temperature area, and moving each batch to the sales floor as they deem it ready to sell, then managing the display carefully to keep it optimally appealing. You can see how this needs more time, attention, and expertise than something that can be received and immediately heaved onto the display. Sacks of potatoes it is not.
posted by jocelmeow at 6:48 PM on July 16, 2013 [15 favorites]

Jocelmeow, do you have any idea why I can get such good goddamn peaches at Costco, of all places? I find that if I grab a flat of their peaches when they are soft enough to feel yielding, then I am pretty much guaranteed to have peaches so delicious that my kids will literally reach over a cupcake to grab a peach. (But if they're hard, then it's pretty dicey.) The only place I've had more consistent luck with peaches is at the farm stand out on the other side of the mountains, in actual fruit-growing country.
posted by KathrynT at 12:52 PM on July 17, 2013

KathrynT, my other food biz job happens to have been working on the club store team at Kellogg's HQ (that's Costco, Sam's, and B.J.'s mostly), so I can hazard a guess but am not an expert on their produce business specifically.

Part of Costco's business model, you've probably noticed, is that they go for a "treasure hunt" effect, bringing products in and out over the course of the year to keep people coming back to see what is new. So unlike a traditional grocery store, they don't have to offer every produce item available all the time - they can select what they want to offer when it's at its best. That means they can be more choosy about which of the hundreds of stone fruit varieties to sell over the course of the season, since they don't always have to fill a slot specifically with peaches or nectarines. Just like other fruits and vegetables, each variety is a little different, and of course, there are some that are a little tastier than others on average.

Now for my speculation: They are definitely a large and coveted account, so I think it's likely they're paying for and getting better-than-average fruit to begin with. I don't have personal experience of their handling practices, but my bet is that their more-centralized business model and better-compensated workers probably also play some part in your good experience.

Why you've had trouble with hard fruit is tough to say. Generally, if it's gotten enough time on the tree, it should eventually soften. However, there is an exception to that. There are some varieties that don't soften appreciably as they ripen - those are called "non-melting" (with the type that do soften being "melting"), and they'd be more common to encounter toward the end of the season. Non-melting peaches taste a little "cooked," even when fresh, so that might help you tell if that's the issue. Most peaches for fresh eating are the melting type. Most that go to be canned are non-melting (and are grown specifically for that purpose).

For folks who are curious about how having hundreds of varieties plays out, here's a maturity chart showing the approximate harvest dates for the varieties sold by one particular nursery. Fruit breeders work not only to develop good-tasting, attractive, productive varieties, but also varieties that will fit into timing niches that will make them competitive with what already exists.
posted by jocelmeow at 5:36 PM on July 17, 2013 [12 favorites]

That chart is outstandingly cool, and thank you for your comments. IME Wegmans is one of the better of the supermarket chains about their peaches, and it's interesting to hear that they are putting so much effort into getting it right.
posted by LobsterMitten at 1:19 PM on July 18, 2013

Instead of the paper bag, I often put peaches next to my bananas and/or tomatoes, both of which produce more ethylene gas as they ripen. Seems to work really well!
posted by odin53 at 5:56 PM on July 18, 2013 [1 favorite]

Nelson: "(Off to go eat some delicious Rainier Cherries. For some reason those do well in grocery stores.)"

Not in Wal-Mart (or Sam's, either).

Since I discovered Ranier cherries some years ago, I've made it known amongst basically everyone I know that I love them very much. Somehow they manage to sell boxes that are about a third rotten, a third unripe, and a third decent, almost every time. They usually look fine under all but very close inspection, but they're never as good as the ones I get from the supermarket down the street. Those are occasionally underripe at the beginning of the season, but never is it a mishmash of fruit at so many different stages of ripeness all in one container.

Even this year, after Wal-Mart's fresh produce marketing blitz, they still managed to sell someone one of their mediocre boxes who then brought it to me. Not that I'd ever complain to the kind souls who bring me cherries! How could I when I get a third of a pint of perfectly delicious cherries and another third that may eventually ripen?
posted by wierdo at 6:53 PM on July 18, 2013

I heard a chef once say that the key to quality cooking is having a surplus of the ingredients so you can cut out the worst bits and just cook with the best. With poor ingredients, like unevenly ripe cherries, you can usually find enough good bits, but tossing out lots of bad bits is inefficient and wasteful.
posted by charlie don't surf at 6:28 AM on July 19, 2013 [1 favorite]

Happy to help, LobsterMitten. Wierdo, I wonder if part of your cherry problem is that the orchard they came from was strip picked, meaning picked all at the same time, rather than in several rounds. It's undoubtedly cheaper to do that, but it can result in uneven ripeness in the finished product. There is also some variation in flavor in stone fruits (including cherries) based on where the individual fruit grew on the tree. Stuff you can reach from the ground is less flavorful, and anything that requires a ladder is more so. But I'm not a cherry expert. I've definitely experienced the same thing with Rainiers especially, though.

Further reading: If anyone is curious about the world of stone fruit breeding and growing, there are a couple excellent books I'd recommend. One is The Perfect Fruit by Chip Brantley, about pluots. The other is Epitaph for a Peach by Mas Masumoto. If you like The Omnivore's Dilemma both of these will certainly appeal.
posted by jocelmeow at 8:57 AM on July 19, 2013 [2 favorites]

Wow. Just found jocelmeow's comments via the sidebar and I am very happy I did. I have a solitary peach tree that puts out far more peaches than we know how to deal with, and for the first time canned the majority of the fruit. Harvesting it has been hard, as the peaches seem to go from "not ready yet" to "damn, too ripe" in a matter of days some years. I diligently watched this year, but the comments here help tremendously in understanding how to catch the magic window, even if I'm just trying to eat them or can them here. Thanks jocelmeow!

By the way, any canning knowledge with peaches? Pectin, no pectin, sugar, no sugar? We tried several different methods because I couldn't seem to find a definitive internet answer.
posted by Big_B at 9:00 AM on July 28, 2013 [1 favorite]