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Thread: Water (Double Boiled) any difference?

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    Senior Member redzone121's Avatar
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    Water (Double Boiled) any difference?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I was reading about water temps yesterday and came across the comment that water that had been boiled more than once made tea (yep tea) taste flat. Anyone got any info on the effects on coffee. Obviously an espresso machine does its own thing but I was thinking more of pour over. Mods move me on if in wrong section ;)

    Cheers

    Chris

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    Re: Water (Double Boiled) any difference?

    I was under the impression that water was best served at about 93 degrees, thus not burning the water or other additive (tea or coffee).

    If this is true then Im not surprised the tea tasted flat.


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    Senior Member GregWormald's Avatar
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    Re: Water (Double Boiled) any difference?

    Water for making tea should never be boiled--only heated to boiling temperature.

    Im sure there is some theory about the dissolved oxygen being boiled away and that affecting taste, but given the amount of dissolved oxygen in city water I doubt if anyone could tell.

    Boiling water does reduce the hardness however, but only to the levels that most authorities say is appropriate for coffee.

    Jim Schulmans "Insanely Long Water FAQ" at http://www.big-rick.com/coffee/waterfaq.html will give you (probably) more than you ever wanted to know.

    Greg

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    Re: Water (Double Boiled) any difference?

    This is an excellent question.

    First of all, lets get one thing out of the way. Ronin, regarding your 93C point: 93C is probably a good starting point for an unknown espresso blend, but it is certainly not the be all and end all. I certainly have benefited from being able to make adjustments to brew temperatures whilst keeping other variables constant. For example, some of the lighter roasts coming from the more new-school coffee dudes benefit from being brewed at a higher temperature, like 95C, whilst some of the more old school big bodied blends do better at a temperature lower than 93C. It may well be that part of the reason why peoples opinions on a particular differ so much is because they are brewing it on machines at different temperatures. And thats just for espresso; once you get to other brewing methods and start talking about tea, Im sure that experience will show that the world is bigger than 93C.

    I have read various points of view on this. Most sources start off by talking about dissolved oxygen and then seem to link it in to a conclusion that the author takes as self-evident. Mostly, that conclusion seems to be that water should always be heated freshly - the thinking being that obviously a low dissolved oxygen content is bad. I dont quite understand why coffee people make this association, given that they all seem to agree that oxygen is the enemy when it comes to storage of roasted coffee. Michael Sivetz book states that water should always be brought to a rolling boil before brewing - I recall thinking that it sounded like Sivetz took it to be self-evident that a high dissolved oxygen content is bad, but it wouldnt be surprising if Sivetz based it on something more than that.

    In terms of theory, I would guess that there is little point talking about dissolved oxygen content divorced from the rest of the attributes of the water. As with everything else in coffee, I would guess that the cup is the result of the combined effect of all of the relevant factors or the dominating effect of one factor that is out of whack. For my part, Im happy to focus my energies on the things that I do know for certain make a big difference.

    All of that said, a while back I wanted to be sure that this factor wasnt screwing up results from cupping, so to try to see if it was a problem, I did a triangle cupping of coffee brewed with water that I had held at a rolling boil for 20 minutes against the same coffee brewed with water brought freshly just to boiling point. I wasnt able to pick the odd cup out, so I was content not to worry too much about it. That said, a really thorough exploration of the topic would require the triangle to be repeated more times with more coffees, more waters and more tasters.

    Cheers,

    Luca

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    Re: Water (Double Boiled) any difference?

    Hi CSrs,

    Dissolved Oxygen?
    Did the original myth creators do the appropriate experiments to justify their assumptions?
    My guess is that elevated temps within the range coffee and tea drinkers use would produce a lot of zero readings. It would be good to put the dissolved oxygen myth to rest though.
    A scientist CSr with an oxygen electrode handy may be willing to take some readings of water heated to various temps for various times, then sealed and cooled (I dont think that theres a Nobel prize in it though).

    Lindsay

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    Senior Member redzone121's Avatar
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    Re: Water (Double Boiled) any difference?

    Thanks for the replies team. If it was a simple answer....well, it just wouldnt be coffee would it? ;)

    Greg, Ill put a week aside to read that link ;D

    Chris


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    Re: Water (Double Boiled) any difference?

    Let me murk up the water all the more.

    I am a marine engineer, on a steam ship, and so my daily work involves water, steam and dissolved gasses.

    If you put a pot of tap water on the stove top and watch what happens as it comes to the boil, there are some stages it goes through.

    As the water is heated, it initially degasses, as the ability of the water to retain dissolve gasses is temperature driven, the hotter the water, the less dissolved gasses, up to the boiling point when there are no dissolved gasses in the water.
    The degassing is seen as bubbles forming on the bottom of the pot, but these bubbles will rise all the way to the surface as they are gasses, not steam.
    As an aside, Trout are a cool climate fish as they need dissolved oxygen in the water to function, the hotter the water, the less dissolved oxygen, and they go off the bite.

    As the water comes close to the boiling point, the water at the bottom of the pot, against the hottest surface, is changed into steam, but as the water above the bottom is cooler than the steam bubble, it cools down and condenses back into water, this happens reasonably quickly and generates an implosion (the reverse of an explosion, inwards rather than outwards) that generates the noise you can hear.
    This is the same affect as cavitation on propellers, and if it takes place against a surface can cause considerable damage.
    It doesnt cause damage in this case as it is occuring in the middle of the water column.
    As the water gets closer to the boiling point, the steam bubbles raise higher in the column before condensing and collapsing until they get all the way to the top and you have a rolling boil.

    Dissolved gasses, especially dissolved oxygen, is bad news for high pressure boilers (6MPa or 900 psi) and we use the property of water at boiling point to drive the gasses out before scavenging any remaining gasses through chemicals such as hydrazine, which you dont want anywhere near coffee, trust me.

    Now back to the original question about boiled before water.
    It has been degassed, and so will taste flat as described, but this will happen in the boiler anyway, and is the cause of the "false pressure" in the boiler when the machine is started.
    Back in the swagman days, they used to have billy boiling races, and one of the tricks was to use boiled before water, as it boils faster than gassed up water.

    Typical engineer, too much information, but knowledge is power 8-)

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    Senior Member Koffee_Kosmo's Avatar
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    Re: Water (Double Boiled) any difference?

    I knew that
    I mean this bit about trout going off there food when its to hot ::)
    Quote Originally Posted by 4E616B7622486E6B686A7B0F0 link=1245718204/6#6 date=1245884315
    As an aside, Trout are a cool climate fish as they need dissolved oxygen in the water to function, the hotter the water, the less dissolved oxygen, and they go off the bite
    KK

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    Re: Water (Double Boiled) any difference?

    Quote Originally Posted by 012E24396D072124272534400 link=1245718204/6#6 date=1245884315
    Let me murk up the water all the more.
    Typical engineer, too much information, but knowledge is power 8-)
    Hi AG,

    Re: the degassing story:
    Mate you are clarifying the water and my only complaint is we need more info to put this to rest.
    My Qs
    Do you have a handle on the holding time for degassing to occur?
    Have you come across data on steady state [oxygen] in water vs temp?
    My assumptions are:
    That drinkers of cooled boiled water would taste the described flatness and assume that tea made with flat water would be inferior.
    That drinkers of boiling water would be in deep trouble.
    People who know the whole answer are scarce.
    People who have the capacity to find the whole truth couldnt care, I hope Im wrong on this one.

    Lindsay

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    Re: Water (Double Boiled) any difference?

    Quote Originally Posted by 3530373D2A38202B38590 link=1245718204/8#8 date=1245898755
    People who have the capacity to find the whole truth couldnt care, I hope Im wrong on this one.

    I guess what is in the cup is what really matters.
    If you like what you are tasting, keep doing it

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    Re: Water (Double Boiled) any difference?

    Quote Originally Posted by 19363C21751F393C3F3D2C580 link=1245718204/6#6 date=1245884315
    Back in the swagman days, they used to have billy boiling races, and one of the tricks was to use boiled before water, as it boils faster than gassed up water.
    8-)

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    Senior Member Koffee_Kosmo's Avatar
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    Re: Water (Double Boiled) any difference?

    Hey Andy_Gadget

    If when water is boiled the and oxygen has escaped in the process

    Is oxygen then introduced back into the water by stirring with a spoon. As a fish tank pump does ??

    KK


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    Re: Water (Double Boiled) any difference?

    To expand this further, I need to do some more research into drinking water, which is sort of my job as well, as I run the fresh water makers on board my ship, 35 tonne a day of fresh water from sea water.
    5 tonne of the water we make a day is boiler makeup water, and so has to be a close to pure water as we can get it to be, and it goes through an ion exchange filter before entering the condensate system, as hardness is detrimental to boilers just as free oxygen is.
    The water that is consumed as domestic water has all sorts of salts added back into it again, magnesium sulfate and magnesium carbinate, sodium chloride (table salt) and calcium chloride, as distilled water is horrible stuff.
    It strips metal salts out of anything it is in contact with and is bad in teeth for this reason, tastes horrible as well, pure isnt always better.

    Dissolved salts in boilers are different to, but here we have some crossover as they affect coffee machine boilers sort of the same way, only sort of as pressure makes a big difference here.

    On high pressure boilers we are more interested in scale forming salts as they can kill a boiler quickly if the water treatment isnt correct, tubes can burst if it gets bad, but on a coffee machine boiler all it will kill is the heating element.
    It does this by acting as insulation and stopping the transfer of heat to the water in both cases, over heating the tubes in the boiler case, but overheating the element in the coffee machine case, much less dramatic than a burst tube, trust me on this.
    But it is these scale forming salts that we add back into the water to make it potable, a catch 22 situation.

    When the doseing pumps that add the salts back into the water stop working for what ever reason, it is noticeable both in the quality of the drinking water (taste) and in the brasko (marine talk for the shower) as the water goes too soft and the soap is hard to get off.

    We look at the consentration of scale forming salts in proportion to the total salts (measured as TDS [total dissolved solids])

    We also look for sodium concentration as an indication of sea water leaks in the system, as sodium chloride is by far the biggest part of the salts in sea water.
    Getting off the point here, so I will shut up for now.

    So I am off into the endless land of the interweb to do some research into this subject so I can answer more clearly.

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    Re: Water (Double Boiled) any difference?

    Quote Originally Posted by 290D040407073D290D110F0D620 link=1245718204/11#11 date=1245905309
    Hey Andy_Gadget

    If when water is boiled the and oxygen has escaped in the process

    Is oxygen then introduced back into the water by stirring with a spoon. *As a fish tank pump does ??

    KK
    Some will re-enter the fluid, but not a lot as it is still hot, but I would think it needs a lot more agitation before it makes a difference.
    This is why they have the paddle spray thingies in aquaculture ponds, to get oxygen into the water.

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    Re: Water (Double Boiled) any difference?

    CSrs,
    Coffee drives the world.
    Another bit of apparently unrelated water/steam trivia for your delectation:
    My uncle was an old railway steam engine man turned Mallee steam traction engineer amongst many other things.
    Water was valued for various steamers in the mallee he claimed the best water was rain water collected over gum leaves and bark.
    The gum debris gave up their tannins which act as rust inhibitors into the rain water.
    We never used it for coffee though only tea.

    Lindsay

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    Re: Water (Double Boiled) any difference?

    I have done some internet research, and it confirms my initial thoughts on Oxygen being the main flavor contributing gas, but that it is the least of the dissolved gases in the water, and is driven out by heating.

    Carbon dioxide is the next most important, and is much more soluable in water than Oxygen, but is again driven out by heating.

    The hardness of the water is not affected by heating unlike the gases, but will only concentrate in the system if the water is boiled and the steam consumed to texture milk, as the harness salts arent carried out in the steam.
    So If you mainly do short blacks, and dont texture milk, it is of much less importance.

    Here is some snippits of what I found on the web with a simple search of "water dissolved gases taste" in google.

    A high DO level in a community water supply is good because it makes drinking water taste better. However, high DO levels speed up corrosion in water pipes. For this reason, industries use water with the least possible amount of dissolved oxygen. Water used in very low pressure boilers have no more than 2.0 ppm of DO, but most boiler plant operators try to keep oxygen levels to 0.007 ppm or less.

    DISSOLVED SOLIDS
    Total dissolved solids (TDS) are the sum total of all mineral compounds dissolved in the water. They consist primarily of salts of calcium, magnesium or sodium usually in the form of chlorides, sulfates, or bicarbonates.
    Excessive dissolved solids decrease the effectiveness of a water softener. While softening will greatly improve water for laundering and bathing purposes, high TDS content in water will exhibit a salty or brackish taste. In cases where water is high in TDS or chlorides (over 250 ppm), only reverse osmosis, demineralization, or distillation will significantly improve water quality.

    The following experiment will illustrate that air is dissolved in water.

    Experiment. Place a tumbler of fresh well-water or tap-water in a warm place. After a time, bubbles will be seen collecting on the sides of the glass. This is air which was dissolved in the water. As the water grows warm, it cannot hold so much air in solution and some of it separates.

    Distilled water has a flat taste, because air and other dissolved substances which give water its taste have been removed. It will again dissolve the air on being poured several times from one vessel into another.

    Rain is water which has been evaporated from the surfaces of natural bodies of water, oceans, lakes, and from the land, and is practically free from mineral matter, but contains dissolved gases.

    Water is a nearly universal solvent. It dissolves more substances and these in larger quantities than any other liquid. At a given temperature, water will dissolve only a certain proportion of the various salts and other soluble substances. When the water will take up no more, the solution is said to be saturated. Increasing the temperature generally increases the dissolving power of water for solids and liquids. The reverse is usually true for gases.

    Silver, copper, and tin are not perceptibly dissolved in pure water, but when combined with acid substances, the compounds formed are soluble. These compounds of a metal with an acid are called salts. The salts of copper, zinc, and lead are poisonous. Copper, brass, (an alloy of copper with zinc) tin, solder, and iron are metals easily affected by acids, so that cooking utensils made of these materials should not be used with acid substances like lemon and vinegar.

    All gases will dissolve to a greater or lesser extent in water. As we have seen, oxygen has a low solubility in water, as do nitrogen, argon and some of the other gases present in the atmosphere.

    Carbon dioxide, by contrast, is very soluble in water: 1 m3 of water at 20C will hold 878 g of pure carbon dioxide. However, carbon dioxide is special for another reason. When carbon dioxide dissolves, it reacts with the water to form bicarbonate and carbonate ions.

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    Re: Water (Double Boiled) any difference?

    Behmor Brazen - $249 - Free Freight
    quote author=68474D50046E484D4E4C5D290 link=1245718204/15#15 date=1246014887]
    A high DO level in a community water supply is good because it makes drinking water taste better.
    [/QUOTE]

    Quote Originally Posted by 62464F4F4C4C7662465A4446290 link=1245718204/11#11 date=1245905309
    If when water is boiled the and oxygen has escaped in the process

    Is oxygen then introduced back into the water by stirring with a spoon. As a fish tank pump does ??
    Here is an interesting table I found on the web (at address below)
    Solubility of solutes as a function of temperature
    (mg of solutes per liter of water):
    O2 = oxygen, CO2 = carbon dioxide

    Solute Temperature (Deg C)
    0 20 40 60 80 100
    02 69 43 31 14 0 0
    CO2 3350 1690 970 580 0 0

    http://www.sensorex.com/support/education/DO_education.html

    This table indicates the amount of dissolved atmospheric gasses presumably at a standard atmospheric composition and pressure.

    This table indicates what the equilibrium concentrations are for water at various temperatures. When heating a container of water, by the time it has been heated to 80 degrees C it will have given up any dissolved oxygen and carbon dioxide, what delay if any, in reaching this state is not indicated. I would guess it would not be a long delay.
    If the same container of water was cooled, to re-saturate the water with these solutes would be quite a slow process.
    The solute concentration in the overlying atmosphere and the surface area available for gas exchange would have a bearing on the time required (an aquarium pump or paddle wheel would increase the available surface area for gas exchange).

    Not too dry as a topic I hope?

    Lindsay



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