A blade grinder investigation I'm considering

[Bohan]

The problem with blade grinders are heat and fines. I ordered one anyway for various reasons and I'm considering investigating exactly how much heat is generated from pulsing it with one serving of coffee beans. I could get a cheap infrared thermometer from Malaysia for $6.99.

To help reduce fines, some people pulse and shake blade grinders, but you can also use a sieve. I read that to prevent bitterness, coffee producers should ensure that the amount of fines passing a #30 sieve doesn't exceed 24% (*COFFEE:AN EXPORTERS GUIDE Geneva 2002). I found a 200mm diameter #30 stainless steel sieve from China for $10.98. It would be somewhat wasteful to create fines that are then thrown away, but I'd be able to eliminate almost all of them which may improve the taste no matter what grinder you use.

A blade grinder plus the above two items costs about $38.

 

[shadow745]

It isn't just about particle size/fines, but also the shape of the particles. A blade 'grinder' basically pulverizes the coffee in all directions until a particular particle size is achieved, whereas a proper burr set utilizes a precise slicing action to achieve a particular particle size in one pass.

Do let us know your findings though as it's likely not many people would bother doing an experiment such as this. Guess you never know till you do try.

 

[John P]

As shadow745 points out, it's a pulverizer, not a grinder. The reason this is important is that coffee/espresso extraction is about the ability to control particle size (can't do that with the blade) and the evenness of the particles (can't do that either). So what you end up doing is both over extracting and under extracting in the same cup as well as the remainder of the cup being inconsistent.

I think you will toss a lot of coffee fines, and spend a lot of time doing something you could have solved by buying a $30-$60 ceramic burr hand grinder. But if it helps you understand the science of coffee a little bit better, that's a good thing.

 

[Bohan]

I'll continue to look for evidence that that stuff makes a difference in taste. You could also say that the ceramic burr ruins the taste by absorbing too much oil, or the oil in the burr goes rancid and affects the taste, or since it doesn't conduct heat, the heat from grinding stays in the coffee. I wish there was just one taste test video on YouTube for every 100 times I've read the typical claims about blade grinders.

 

[duc687]

A blade grinder is like a blade mower it doesn't actually cut it pulverizes
(A reel mover would be closer to a burr grinder in that it actually cuts/shears grass)
The thing is the rpm's are also an issue the heat and static that comes with the nearly 18,000 rpm's (my burr grinder is 600rpm)
and the pulverized beans all affect flavour...
But do proceed and let us know.



Sent from my iPhone using Tapatalk

 

[Musicphan]

I'll continue to look for evidence that that stuff makes a difference in taste. You could also say that the ceramic burr ruins the taste by absorbing too much oil, or the oil in the burr goes rancid and affects the taste, or since it doesn't conduct heat, the heat from grinding stays in the coffee. I wish there was just one taste test video on YouTube for every 100 times I've read the typical claims about blade grinders.

That's simple... take out a blade grinder - grind up 2-3 cups worth of coffee. Sift with the coffee with your standard household kitchen strainer. Brew one cup with the fines, one cup with the rough/large grinds... you will taste the difference.

 

[Bohan]

That's simple... take out a blade grinder - grind up 2-3 cups worth of coffee. Sift with the coffee with your standard household kitchen strainer. Brew one cup with the fines, one cup with the rough/large grinds... you will taste the difference.

I agree that there would probably be a significant difference if I did that whether I personally can tell or not, but I wonder if shaking and pulsing the grinder would bring the fines below 25% which seems so be an acceptable level according to the Coffee Exporter's Guide. If not, maybe the sieve I'm considering can take care of that. There are probably lots of things you can isolate from coffee that will taste bad. The solution is to not isolate them.

 

[Musicphan]

I agree that there would probably be a significant difference if I did that whether I personally can tell or not, but I wonder if shaking and pulsing the grinder would bring the fines below 25% which seems so be an acceptable level according to the Coffee Exporter's Guide. If not, maybe the sieve I'm considering can take care of that. There are probably lots of things you can isolate from coffee that will taste bad. The solution is to not isolate them.

I understand... just saying you could sift the coffees so you can taste a coffee that is over extracted (too fine) and under extracted (too coarse). I don't see heat as a big issue with these grinders... the capacity on most is simply not enough your going to heat up the beans to any significant degree. The problem with blade grinders is consistency... you just never know the results and when you grind small enough you get lots of fines.

 

[Bohan]

I got the blade grinder and tried it out on Jim's Organic Coffee, Jo Jo's Java flavor, medium/light roast. I think I ground it a little too fine. I added milk, maybe a little too much. It went through the filter at a decent rate. Seemed good, but I don't think the fines issue is a myth and I think I'll be getting that sieve.