Project history
- old posting: 'roast only' on the Bonaverde - Aldo Parducci
- current posting
- next posting: 'roast only' on the Bonaverde - Familia Alfaro
Before
Up to now I have used tap water with a filter for my coffee experiments.According to the water plant the water should be very hard but be only slightly above Ph neutral.
I always had the issue of always having an acidic taste.
Some coffee cups had a very balanced acidic taste, some where so strong as to be undinkable.
Especially freshly roasted coffe that was not given any time to release trapped CO2.
After
Now I experimented with using cheap bottled water insted.DAMN, WHAT A DIFFECENCE.
Absolutely no sour taste anymore. Roasted the day before and even freshly roasted (with all the CO2 still in there and ALYWAYS tasting distinctly sour before) it tasted like a good cup of coffee.
Sadly it contains 500mg Ca/l+64mg Mg/l=>84,86dH and thus will just about kill the machine with scale if used often.
Why?
Let's have a look...The bottled water was from REWE "Aqua Mia Still" from the Alwa Spring in Sersheim.
There is a nice comparison of German bottled waters here. It has pH values (the content only lets you calculate hardness)
Chlorine
The water plant says, we have 23.1mg/l.The bottled water says, we have 29.0mg/l
The
0mg/l is perfect
effect: in high temperature/pressure this creates hydroloric acid thatg eats away on metal.
There is nothing I can do anything about this except maybe carbon filtration.
But I don't care enough about this minor effect to do that.
pH
The water plant says, we have 7.57pH.The bottled water says: nothing
Water #2 says: nothing
7.0pH is perfect,
6.5-7.5pH is acceptable
effect: abovr 7.5pH this causes excess scale
Next steps: I ordered a digital pH and TPS meters from China for less then 2eur.
Hardness (Calcium only)
The water plant says, we have 75,8mg/l of Calciumand a total hardness (considering not just the Calcium) of 12.5°dH or 2.19mmol/l
The bottled water says, we have 500mg Ca/l+64mg Mg/l=84,86dH
7°dGH/68mg/l is perfect
17-85mg/l is acceptable (first source).
8-12 °dH is acceptable (second source).
3-7 °dH is acceptable (third source).
effect:
Above 85°C this forms scale.
High hardness makes coffee go bitter quickly.
Low hardness supresses the taste of the coffee.
Here is a nice calculator between °dH, mg/l of Calcium-Oxide and ppm CaCO3,...
Or you calculate °dH = 0.1402*[Ca in mg/l ] + 0.2307*[Mg in mg/l ]
Or mmol/l= [Ca in mg/l] / 40 + [Mg in mg/l] / 24,3 .
Sodium (DE: Natrium)
The water plant says, we have 10.2mg/l. But ADD what the water filter releases.The bottled water says, we have 18.0mg/l
10mg/l is perfect.
Anything near that level is acceptable.
The problem may of cause also be that the water filter with my very hard water (12.5°dH or 2.19mmol/l) releases enough sodium (DE: Natrium) to exceed 10mg/l.
The original water already has 10.2mg/l and is thus at the brink of the acceptable level.
Above 50mg/l this seems to cause a sour flavor. (Very low sodium levels seem to cause sweet flavors. That sounds very interesting as it's a taste I generally like.)
TDS=total dissolved solids
The water plant says, we have 75.8mg/l of Calcium + 7.3mg/l Magnesium + 10.2mg/l Natrium+1.7mg/l potassium (DE: Kalium)= 95mg/l I'm not sure I did this calculation correctly and am not missing anything.
The bottled water says, we have 500+29.0+64.0+18.0+5.0=616mg/l
150mg/l is perfect
75-250mg/l is acceptable.
effect:
low=overextraction, tannic taste (DE: Gerbsäure), dry mouth
high=mineral taste, overextraction
Total alkalinity
The water plant says, we have TODOThe bottled water says: 1130mg/l of Sulfate + 414.0mg/l of Bicarbionate (DE: Hydrogencarbonat)
TODO: I need to refresh my chemistry on this topic.
40mg/l is perfect.
Anything near that level is acceptable.
effect: high=gum up outher layer of coffee and cause uneven extraction. Also scale buildup.
Links
- Water quality in Freiburg (Area 4)
