Tuesday, June 22, 2010

Refrigeration Technology Roundup

The world's first refer ship.

Heath Putnam Farms (bka* Wooly Pigs) recently sent a bunch of chilled meat from Missouri to DeBragga and Spitler in New Jersey. The stuff will wind up in some of NYC's best restaurants.

It is a big accomplishment to make this work, because many consumers insist on never-frozen meat - especially the Michelin-starred chefs that want to our stuff. It is hard to sell a top-quality product if it has perceived flaws, and these days, many perceive "previously frozen" as a flaw.

The timing of our first chilled meat load was great - pigs got cut on Wednesday and Thursday, picked up on Friday and were delivered to NJ Monday morning. You can't expect it to go much better, unless you run a dedicated truck, and even then, you'd only save a few days.

Modern packaging technology - eg Cryovac (TM) makes it possible to move meat around a large country like the USA, because it greatly reduces spoiling. If you don't have Cryovac or similar technology, but have refrigeration, you've got two choices: operate chilled and local or frozen (and potentially very remote).

It helps to understand those two choices by going back even further: pre-refrigeration.

Basically, meat spoils quickly. Around 40F, you've got bacteria multiplying rapidly. This is why in countries without refrigeration, you'll have slaughter and processing in urban areas, where people can afford meat:

Really local meat - Image copied from flickr.

Before refrigeration, chilled meat was pretty much all "local", because non-local chilled meat was rotten and unsaleable.

With pigs, pre-refrigeration technology included (assuming ambient temperatures were cold enough) immediate processing into shelf-stable products like country hams, speck (aka bacon) and fermented sausage like salami. The Chinese, who've raised pigs longer than anybody, have been making such products essentially forever, in addition to breeding pigs like the Mangalitsa that make very good versions of those products.

When you've got refrigeration, you can kill, chill and process, distributing the meat within days/weeks. That, in conjunction with hygiene improvements like a refrigerated meat case, is a big step above the pre-refrigeration system - but you'll probably still have slaughterhouses and rendering facilities in cities, which stink.

Among other reasons, with refrigeration alone, it isn't possible to economically transport chilled meat cheaply, because if you stack or pile it up, it heats up and spoils. E.g. throw 1000# of chilled meat from recently killed pigs into a box and stick it in a refrigerator and the meat generates heat. The core temperature will get around 40F and then you've got major rot underway.

However, refrigeration does get you frozen meat, and that stuff lasts and can be transported great distances. Or you can use it to postpone processing of meat, as the Spanish do with their Iberico pork.

As described in Wikipedia, frozen meat is amazingly old. That picture above shows the first refer ship - it was powered by wind.
The Dunedin About this sound listen (help·info) (1876–82) was the first ship to complete a truly successful transport of refrigerated meat. In its capacity, it helped set the stage for New Zealand's success as a major provider of agricultural exports, notwithstanding its extreme remoteness from most markets.
A lot of meat you eat in restaurants is previously frozen, either by the meat company or the chef. I suspect many chefs insist on never-frozen meat because they know they'll probably need to freeze some of it.

The next major innovation, that makes possible the distribution of chilled meat over great distances, is Cryovac (TM) technology.

You might think Cryovac is new stuff, given that it relies on plastic bags and is spelled like a modern trademark - but the technology is actually quite old - approximately 70 years.

I was surprised to find this out. Here's an article from 1939 about Cryovac technology:
In 1937 a French scientist named Maurice Piettre, when he arrived in the U. S. for a conference on food processing, told of new wrapping material then being tried in France for refrigerated meats. The material was latex—pure natural rubber altered just enough to be workable. The trick sounded good to Dewey and Almy Chemical Co. of Cambridge, Mass., which was already using latex to make low-cost balloons ($2.25) for high-altitude meteorological and cosmic ray observation. The company's researchers set to work devising a commercial method for wrapping poultry and meat in latex.

To get a sense of how long ago that was, here's a video from that era, when "mangalica" pigs were still very common in Hungary:

Remember, that's pre-internet, pre-satellites, pre-mobile phones, pre-computers, pre-plastic, pre-petroleum chemistry, pre-pretty-much-everything-we-rely-on-today.

It really surpises me that in an era when some Europeans were still living so traditionally, we had cryovaced meat - but that's not much more surprising than the idea that back in 1876, we had refrigerated ships, powered by wind.

Of course, Cryovac (TM) technology isn't rocket science. You put the meat in a bag, suck out all the air and keep the stuff chilled. That's it. If you do that, the anaerobic environment greatly retards the growth of bacteria. Pork keeps for weeks. Beef can keep for months.

Unfortunately, the bacteria that does grow in anaerobic conditions is fairly stinky, leading to discussions like these between chefs:

hi, I went to a meat packing house that also serves to the general public and bought a huge hunk of skirt steak for cheap, it came in a cryovac bag. I've never had experience with this. When I opened up the bag, it reeked! I trimmed some of the fat and washed it and that seemed to help. I cooked some of it today, and put the rest in the freezer and it tasted fine


As to anaerobic "rot:" We sometimes toss terms around a little loosely. Actual anaerobic rot is usually the result of a type of bacterial organism called lacto-bacillae aka LABs. If, in addition to the smell you get when you open the bag, there's significant discoloration (not just darkening, but green or rainbow), and/or sliming, and/or the odor persists after the cleaning, the meat should be discarded. Otherwise, you're good to go.

If the seal breaks though - watch out. In the presence of oxygen, the meat rots much faster. That's why chefs are taught to reject "leakers" - bagged meat that isn't vacuumed sealed. Of course, if the meat is frozen, a punctured seal is much less of an issue, because there won't be rot.

Of course, once you can distribute chilled meat over great distances economically - thanks to Cryovac (TM) technology (whether powered by latex or plastic), there's no reason to have slaughterhouses and rendering plants in cities. I suspect that most people don't realize this. If we moved from our current to system to one with slaughterhouses in or close to major cities, we'd have odors and hygiene problems, as we did in the past, and it wouldn't be possible to use that real estate for other purposes.

* bka = "better known as"

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