# Beans differences and temperature



## oracleuser (Sep 26, 2018)

First question: Does temperature makes a difference?

I was yesterday using Lavazza Perfetto beans and set my grinder to a setting of 16 of 40 which made a perfect shot.

This morning i took fresh beans of the same package i vacuumed some days ago out of the fridge and the shot was overextracted. I had to put the grinder coarser to 20 and then it worked again. What could be the reason of that? The temperature or can there even be differences in one package?

Second question: Can beans SO different?

When i got the machine i also experimented just for fun with the cheapest no-name beans they had in the supermarket which were very light roasted.

With this beans i could never got a an acceptable shot. Even when i put the grinder to very fine the shot was still totally underextracted. I got over 100 ml (!) even with a fine coarse. With the Lavazzas i would may have given 10 ml on this grind settings. Can beans SO different? And are this very cheap beans totally unsable on machines like the Oracle or do i got something wrong?


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## Jony (Sep 8, 2017)

I would say yes they act different. Not the best of beans either


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## kennyboy993 (Jan 23, 2017)

You didn't do anything wrong - you've just learnt that making good coffee isn't as repeatable as we wish it was...... 

Seriously though - could be anything..... from bean humidity or temp to grinds prep and different extraction etc.

It's a heuristic game - wish it wasn't


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## oracleuser (Sep 26, 2018)

kennyboy993 said:


> You didn't do anything wrong


I am in doubt the machine is the problem. Doesn't matter what i am doing - shots are going crazy from 50 to 90 ml.

I guess i will send the oracle back and get a manual setup with seperate grinder-


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## Rob1 (Apr 9, 2015)

Ooookay...

Light roasts need a finer grind than dark roasts. There can also be some variation due to bean variety (so maybe you won't have to adjust so much for a dark roast of one variety and a lighter roast of another Vs the same variety and origin taken to a different level). The amount you have to adjust by will vary depending on your burr type too.

Are weighing your dose?

Are you weighing your output?

Why are you keeping your beans in the fridge?

Get some decent beans, weigh your dose and see what happens. If you've loaded the hopper, you're purging stale grinds, you're weighing your dose before you brew, and you are doing any prep such as redistribution and tamping in a way that is consistent and repeatable, you are likely to get repeatable shots. Any variation in any of the above and you won't.

Edit: Except for tamping. So long as it's flat and with approx 5-6kg of force (very easily done) it won't really affect shot time significantly, so there's no point worrying about whether or not you're tamping hard enough.


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## Mr T (Nov 6, 2018)

Is it really noticeable what tool you use for tamping?


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## hotmetal (Oct 31, 2013)

Kinda. There are flat, convex and hybrid variations. The theory is different but the aim is the same. You need the coffee to seal correctly at the edge of the basket (to prevent the water running down the edges instead of through the puck) and you want the puck to be of an even density so all the coffee is extracted evenly. Each base style has its pros and cons (allegedly). The idea of the convex is that it forces some of the grinds outwards to promote edge sealing. Flat, well, that's self explanatory. Plan2Convex tries to be the best of both.

I've had various tampers and currently swap back and forth between a Torr Goldfinger sharp edge flat and a convex. Both of these are machined to fit precisely in the VST basket.

If I am honest, both work equally well. More important than base shape IMO is the quality of the fit. Cheap "58mm" tampers, or worse still the free plastic things you get with some machines, simply don't fit well enough, which means you end up tamping around to try to seal the edges. This drove me nuts. I measured my "58mm cheapy" and it was 57.3mm. I bought a 58.4 which is 58.4, and a 58.5 (also accurate) and both are excellent. 57.3 is like the proverbial 'pr*ck in a bowler hat' as one of my buddies likes to say.

All the stuff about flat v convex, or special metals, or a specific tamping pressure etc are (in my amateur experience) niceties of secondary importance. Fit is king. After that you can worry about the other stuff if you feel the need.

This is a subject that has been debated for years buy the great and the good, with scientific measurements, and I won't try to argue with the professionals. But in my experience the following seemed about right:

Tamper must fit the basket.

Flat tampers are the easiest to see when they're truly level. Pressure feedback to the hand is very linear and abrupt.

Convex tampers can be 'more forgiving' and the feeling in the hand is different. They do help seal the edges, but a flat tamper on a well prepped coffee bed will also be just as good. Some have argued that average extraction yield from convex tampers is some tenths of a % behind that of a flat. I really wouldn't know!

Distributing the coffee evenly before tamping is more important than flat vs convex. The tamper should be level, as should the puck at the end.

Forget trying to learn a specific pressure. "Until it stops" is likely to be more repeatable in the real world, and in any case, the idea is to compact the grounds so they present a uniform resistance. Tamping until you feel it won't go further seems to fit the bill. Use grind to steer the extraction, not tamp pressure. You don't need to really lean on it, just apply enough consistent pressure with no attempt to 'tamp lighter' but not so hard you give yourself RSI.

On that note, all the above is based on home experience. In a professional setting, different rules may apply when there are several people trying to achieve consistency, and also avoid injury when making hundreds of cups a day.

___

Eat, drink and be merry


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## TimO (Nov 2, 2018)

Don't forget the 'human' element, we are very complex creatures and how we taste differs on how we are in ourselves. Something that might be identical, can taste wonderful one day and average the next. Subtle I know, but we don't just taste by what's on our tongues - so many other factors at play here.

This can either make life interesting or mind numbingly frustrating, especially to perfectionists


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