By now most people know the term “Blockchain”.  They know that a small group of people fervently believe it is a technology that is going to change the world, or at the very least make them rich.  But few people know how it actually works — myself included.
On the other hand, I have a pretty good idea how the fresh produce industry works.  So when I heard the news that Wal-Mart, one of the largest buyers of fresh produce in the U.S., plans to use Blockchain technology to “make leafy greens safer”, I immediately got suspicious.
Food borne illness is essentially a problem of scale.  It’s a Walmart problem.  If everyone bought only locally-grown and prepared food, there would be few incidents of widespread food borne illness. But when thousands or tens of thousands of people eat the same batch of contaminated food, dozens or hundreds may get sick, making it an “outbreak”.
Back in the early 2000s when a batch of spinach produced by Earthbound Farm made people all over the U.S. sick, Earthbound’s management learned that most of those people had purchased the spinach 10 days after it had been harvested.  They thought they could improve the safety of their products by changing the “sell-by” date from 10 days to 7.  The response from their buyers — outlets including Costco and Walmart — that this change was unacceptable.  They quickly backpedaled.
Fast-forward a dozen years to 2018, when a batch of romaine lettuce was identified as the culprit in another outbreak.  A month after the lettuce was harvested, it was still being found in stores and destroyed.  The fact that lettuce that old was still on store shelves should been an obvious clue as to why people are still getting sick from fresh produce.
Illness-causing Bacteria are living creatures that reproduce as long as they are alive. And the more of them that you eat, the more likely you are to get sick.  Following the logic here, the farther vegetables are shipped and the longer they are kept around, the more bacteria they will harbor.  That’s not a problem that technology is going to solve.
Walmart claims that the Blockchain is going to be able to track a vegetable back to the field it was grown, and the date it was harvested. But that’s not going to keep people from getting sick.   By the time the first illness is reported to the authorities, thousands of other people have already eaten the contaminated product.  Walmart might be able to identify the specific packages of product and remove it from their shelves — but they already do that, using existing technology.
I have no idea how much money Walmart has invested in this ill-advised venture, but it’s easy to guess that it is costing them far less than the simple, low-tech solution:  shortening the “sell-by” dates on their packaged fresh produce.  But that solution doesn’t fit into their business model.
Our society’s current approach to improving food safety is fundamentally flawed.  We’re going 180 degrees in the wrong direction.  Food borne illness has increased because fewer and fewer farms are growing all of our food, and shipping it all over the country.  Everyone is eating produce grown in the same fields at the same time, making many more people vulnerable to contamination by a single event.
Locally grown and purchased food has very little potential to make large numbers of people sick.  But the fresh produce industry and the federal government are making it harder and harder for small growers sell their crops anywhere other than farmers markets.  They are in effect allowing the largest farms, retailers and fast food chains to claim a superior level of food safety, when in fact they are very clearly responsible for the vast majority of food-related illness.
You probably don’t shop at Walmart very often, but you probably do buy packaged salad greens from time to time.  And even with fresh greens from Terra Firma or the farmers’ market, you need to follow basic guidelines.  Here are some practical, low-tech ways to avoid getting sick from fresh salad greens:
— Buy fresh salad greens. If you’re buying packaged pre-cut greens in the store, check the sell-by date.  Subtract 3 days.  If you’re not going to use them before that date, don’t buy them.
— Don’t leave any greens in your car for any length of time, as it will reduce their shelf life dramatically.  Buy them just before heading home, or bring a cooler and a couple of icepacks when you go shopping.
— Smell greens before you use them.  If you smell any musty or fetid odor, throw them out.
— A wilted or damaged leaf here and there is not a sign of decay.  But if there is a layer of rotting salad greens at the bottom of the container, discard all of the greens.
— Washing greens is always recommended, but washing rotten or off-smelling greens does not make them safe to eat.
— All fresh leafy greens are always taste better when eaten or cooked as soon as possible after harvest.