So often when I take the little barcode sticker off the piece of fruit when I'm washing it, I discover a blemish under the sticker. Is that because the sticker was placed so as to cover up the blemish, or because the act of putting on the sticker tends to result in some local damage to the fruit?

  • 18
    You also missed the possibilities that the act of removing the sticker causes damage, or that the sticker somehow results in damage that's not related to it being put on (eg, different permeability, rolling damage as it's slightly higher than the surrounding area, etc.) – Joe Jul 10 at 18:02
  • There's also the fact that the sticker prevents the skin from being exposed to both light and air, affecting ripening. – barbecue Jul 11 at 13:18
  • @Joe, I think you're on to something. I wonder what effect trapping ethylene would have, and certainly inspecting the back of a label after peeling it off can reveal traces of peel. – Chris H Jul 11 at 13:19
  • 1
    I freely admit I haven't measured the frequency. But I've often noticed that in an amazingly unblemished fruit, the only blemish that fruit has resides precisely under the sticker, hidden from view until the sticker comes off. – aparente001 Jul 11 at 13:28
  • 1
    @martin the number is more useful than a barcode. If you’re complaining about grocery stores with self checkout registers, most these days have an option to enter a number, just use that. (Older ones had a camera, and you’d press a button to alert the cashier, and they’d enter the code) – Joe Jul 12 at 14:56

A few years ago I had the rare chance to take a look behind the scenes of the largest manufacturer of fruit sorting, labeling and packaging equipment in the Pacific Northwest and it was impressive to see how much effort and planning goes into designing everything in a way that damage to fruit is avoided at all costs. We talked about how the business evolved and what the biggest challenges are.

And yes, the stickers are a crucial part. Developing a glue that is food-safe, will stick well and come off without damaging the fruit is a challenge and different manufacturers have solved it more or less well. If you observe carefully, you will notice that the stickers will behave differently.

There are two main ways how stickers can lead to damage:

  • Too much local pressure when applying the stickers and
  • A glue that is too sticky and tears the fruit when the sticker is pulled off.

The former will result in a soft spot or other blemish, the latter is visibly fresh. Soft-skinned fruit like peaches are much more prone to damage and a real challenge compared to e.g. apples. The damage is not unavoidable, a lot depends on the settings of the equipment and a good operating personnel.

But I can assure you that no fruit packaging plant will “cover up” blemishes with a sticker - simply because they label way too many pieces per hour. Blemished fruit will be sorted out before packaging, damaged fruit in packs will typically mean the whole package is rejected by wholesalers - because they won’t travel and store well.


Knowing all this, one of my pet peeves is supermarket workers that think refilling displays is best done by upending boxes of apples, but that’s not part of your question.

  • 18
    we, as consumers, sometime lose scale on volume of items that go through facilities like a packing plant. It is easy to think that the tags might be used to cover up when we think of the handful of an item we buy, but what would be involved with doing that on the millions of items going through the plant is not easy to recognize. As someone who has grown and raised product, I so agree it your pet peeve as well and expand it to handles, stockers, and passer-by shoppers who handle items and put them back for others to buy. – dlb Jul 10 at 20:34
  • 1
    On at least two occasions I have pulled the sticker off of a big butternut squash before cleaning and putting in oven to bake, and lo-and-behold found a little gouge (maybe abt. half a cm across, and similar depth) in the relatively tough squash skin. That injury was not caused by me pulling the sticker off or by anyone putting the sticker on in the first place. And considering how big a butternut squash is, the sticker placement was too accurate to be an accident. Maybe it wasn't the farmer or packer who covered up the ding, maybe it was the grocer? But I think it was on purpose. – Lorel C. Jul 10 at 22:08
  • 1
    @muru the problem is mechanical damage: every time someone picks up a piece of fruit and puts it down again it may cause small soft spots and local damage - And think about the shoppers that try to judge ripeness by pushing or pinching the produce. This will cause damage, invisible at first, but rotting soon, either in the store or at other unsuspecting customers’ homes – Stephie Jul 11 at 6:26
  • 1
    @Stephie thanks, posted: cooking.stackexchange.com/q/90953/62710. – muru Jul 11 at 7:51
  • 2
    @Stephie bruises don't cause rotting. As fruit ripens it becomes more susceptible to bruising, and also more susceptible to rotting. Given how incredibly wasteful of wood we are already, finding new reasons to dump perfectly wholesome food into landfills is dubious at best. – barbecue Jul 11 at 13:20

I've often wondered the same thing. Here's a video of stickers being applied to fruit: https://www.youtube.com/watch?v=62nJzuKjUBc

Since it's done mechanically, there's no way to intentionally cover up the bad spots (without spending more money than it's worth). So in other words, the bad spots under the stickers are a coincidence... unless the stickers are moved later on by, say, an employee at the store.

Assuming that the stickers weren't moved, here are a couple of other possible reasons that stickers seem to cover up bad spots so often:

  • some sort of "confirmation bias" (we remember those particular cases because they support our suspicion)
  • the fruit with visible bad spots weren't chosen by the customer

As a student, I used to work at one of the biggest vegetable and fruit processing/trading companies in the world. (They would import/export fruits and vegetables all over the world, and would also sell bags of pre-cut vegetables for instant use).

One of the most boring jobs was putting the stickers on the fruits. Because this was all still done manually. This was done with some kind of "sticker-gun", that gave you a sticker if you pulled the trigger, after which you had to press the tip of the gun on the fruit.

I can imagine that this pressure would be enough to cause a small bruise, that would become visible several days later.

Also: They had some kind of "deal" with a local daycenter for the mentally handicapped. I think it was 3 times a week, the ones that were able to do some basic labour (mostly down-syndrome) came to do some of the basic tasks. One of those tasks was putting the stickers on the fruits.

I can imagine that, even though they were very hard working and responsible, they would have slightly less control of how much pressure they had to put on the fruit and sticker-gun, causing the bruise to be slightly bigger.

Edit: forgot to answer part of the question: in no way was it done on purpose to hide existing bruises. This task was already extremely boring and time consuming, so that no one would take the time to find a bruise to put the sticker on. You would just do "tack tack tack tack", and place it anywhere you could, as fast as possible.

  • I have a friend with Down Syndrome who has some motor planning issues, so I can relate. Also, from your description, I can see that the process could involve some inherent damage to even a slightly soft fruit. – aparente001 Jul 11 at 13:11
  • 2
    @aparente001 To be honest: I think I wrote my answer too negative. I just wanted to point out that it's very unlikely that it's done on purpose to hide existing bruises. Yes, it is possible that someone puts a little too much pressure on a certain point, and thus damages the fruit, but imho I think there are much more plausible explanations to the damages under the labels, for example the glue underneath it, or the lack of sunlight on it. Or maybe even the lack of being able to "sweat" (yes, fruit excrete some kind of oil, maybe if it gets trapped underneath the sticker it causes a defect?) – Opifex Jul 11 at 13:26

I'll offer up an alternative explanation to the two that you mention in your question. Like Stephie explains, stickers are generally applied by automated machinery in a process designed to minimize damage. The packaging process also includes steps to weed out damaged fruit before shipping. If a machine happens to place a sticker so that it covers up existing damage, then the inspection process would be significantly less likely to notice that damage and flag the fruit. It's not malicious sticker placement to fool the buyer, it's coincidental sticker placement that allows an existing blemish to slip past quality control.

I don't have any direct experience with fruit-processing machinery, but I've seen this sort of thing happen on other types of manufacturing/processing equipment. There's a lot of probability involved with the coincidental cover-up so the odds of this happening to a particular piece of fruit are quite low, but multiply that times the volume processed and you get a reasonable chance of this occurring a couple of times a day.

  • 6
    I'm fairly sure the stickers go on after checking. The rejected fruit will end up in processed food, animal feed or compost/anaerobic digestion, none of which can handle a plastic label (at least they're plastic here) – Chris H Jul 11 at 6:04
  • @ChrisH and bta - I'm curious, I wonder what sort of proportion gets rejected in the weeding/checking process? I'm guessing they aim for less than 15%? – aparente001 Jul 11 at 13:12
  • @aparente001 I don't know, but I do know that the supermarkets charge their suppliers for rejects (and I think this applies to other big processors) so there may be some screening even before that. – Chris H Jul 11 at 13:17
  • @ChrisH - possibly, but there also has to be some sort of QC after processing. Otherwise, you'd miss any damage caused during processing and risk shipping damaged product. – bta Jul 11 at 15:54
  • 1
    @bta Many processing facilities have persons at the end of the production line who visually inspect and remove any damaged product. – Cindy Jul 11 at 16:12

Your Answer

 
discard

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.