I'm not in the habit of weighing the beans in a bag of roasted coffee. But recently I repackaged a bunch of coffee and took the time to weigh out the portions exactly. And I found that these bags were 2-5% underweight (20-50g out of 1kg). That seems like a lot to me and if the coffee weren't already a good value I might be upset. But instead I'm just curious. Is this common? I have no idea how coffee is packaged.

Is it possible the beans just lost weight after packaging? Beans contain moisture, much of which is baked out during roasting. Even after roasting, some fraction of the bean weight is water. Depending on roast level and outside humidity, it may still be possible for them to lose weight thru evaporation, I suppose.

Well, since shorting product in a bag is such a bad thing for the person doing the shorting, I would first check your scale but, then bring your scale to the store and weigh a bunch of bags and if you find light one, complain to the manager. That's class action lawsuit stuff and at least a state crime and possibly a federal crime.

I was surprised as to how "loose" the US standards are when I was looking into "a gallon" of water.

From https://www.nist.gov/system/files/docum ... bfinal.pdf Table 2-5, at 1 kg the permissible variance is 35.3 g.

From the same table, for a "12 oz" bag of coffee, the permissible variance is 16.3 g

Finding "a light one" is probably not actionable. Finding consistent underweight using the testing regimen described in other documents might be.

You're allowed 35 grams out of a kg so he's found at least one that is out of spec. I would have thought that with modern packaging equipment they would have tightened that up. I imagine with a small coffee producer it might get overlooked, but if someone found Lays potato chips consistently light, even within the regulations, there would be a stink of massive size.

Ira

Beans will gain moisture if exposed to air. They will lose some CO2 but not 5%.
I tested my scale with good calibration weights and it is dead on.

These bags are from Italy so US standards don't apply. I recall a visit to that country years ago and being amused that they had to stop the train every 30 minutes to pour water on the brakes so they wouldn't catch fire. That was a long time ago and Italy is part of the EU now. Still, I don't know what is typical.

ira wrote:You're allowed 35 grams out of a kg...

Thanks for that. I thought the rule would be tighter than 3.5%.

Jeff wrote:From the same table, for a "12 oz" bag of coffee, the permissible variance is 16.3 g...

...which is about 5%.

jpender wrote:I recall a visit to that country years ago and being amused that they had to stop the train every 30 minutes to pour water on the brakes so they wouldn't catch fire.

OT: We had a similar train experience in Italy.

After spending a few months living in Vienna, I was accustom to trains that departed precisely on time. Locals joked that a sure sign of a tourist was someone waiting by the tracks peering in the distance for the train. While traveling through Italy, we had to connect to another train and it was only a 10 minute difference between the (Austrian) arrival and the (Italian) departure. My wife and I sprinted to make it, much to the amusement of the person at the ticket sales booth. "Why did you run? It will be at least another 30 minutes," they chuckled.

However, I cannot say if the same logic applies to coffees bagged in Italy.

I was in Switzerland once and watched a tourist ask the conductor if he'd hold the train for a couple of minutes for his friends who were coming. The look on that conductor's face was priceless.

I looked it up: The EU has a special symbol "e" that appears next to the weight on the bag, the "estimated sign". For 1000g the tolerance is 1.5% or 15g. So all of these bags were technically underweight. It's still a good value and great coffee so I'm not put off by it.