This is another proposed sticky intended to relieve my typing burden as it is something that is mentioned quite a lot. The intent is not to convince you that you should or shouldn't rely on this ratio as a design parameter but rather to give you a little insight which may help you make an informed decision.
Where did the notion that the ratio was sufficient come from? I believe it was David G. Taylor's chapter "Water" in the Second Edition of Handbook of Brewing edited by Priest and Stewart (CRC Press 2006) in which he says:
"...these ions [sulfate, chloride] are somewhat antagonistic. In an attempt to quantify this point, it has been shown (Ref. 19) that increasing the Cl:SO4 ratio from 1:1 to 2:1 (on a mg/L basis) achieved increased taste panel scores for body and sweetness, with commensurate reduction in drying, bitter, and metallic flavors. In contrast, when the Cl:SO4 ratio was changed from 1:1 to 1:2, the increased sulfate content achieved reduced body and sweetness, but increased bitterness and drying flavors.
"These effects are repeatable at different absolute concentrations of chloride and sulfate. It appears that, in many cases, it is the relative ratio of the two ions that has the major flavor influence, often irrespective of the accompanying cations."
Ref 1: Taylor, D.G,. How water composition affects the taste of beer. Brew. Distill., Int., 11:35-37 1981
I think this to be the source as I started seeing the ratio touted as a design parameter shortly after its appearance.
My first observation is that dry and sweet in the sense of a champagne are definitely antipodal but are bitter and metallic in any sense antipodal to body and sweetness? Furthermore, is the 'dryness' occasioned by sulfate really a reduction in sweetness or a move towards astringency? Taylor himself says sulfate imparts "dryness/astringency". In a paragraph where here gives separate effect. I'll leave this to the readers to decide for themselves.
Now a question to the readership: Does anyone here really think that a beer brewed with 10 mg/L Cl- and 10 mg/L SO4-- is going to taste anything like a beer brewed with 200 mg/L of each? Or that if one goofs and winds up with a ratio of 4:1::SO4:Cl that he can fix the beer by quadrupling the chloride?
Going in we can add as much chloride or as much sulfate as we want to (within reason). We say, in such cases, that there are two degrees of freedom because we are free to set either wherever we want. If we assert that it is only necessary to know the ratio of SO4 to Cl then we no longer have two degrees of freedom but only 1. This is not saying that we still can't put as much of either as we want onto a brew but that it does not matter what the absolute amounts are; only what their ratio is. We all know that adding chloride sweetens the beer, rounds it and enhances its body. We also know that sulfate makes the bitterness harsher, drys the beer and adds metallic tastes (new one on me). Sounds like two degrees of freedom to me but again I'm encouraging people to evaluate this based on their own experiences.
Here's another point to consider. If you say I'm going to use x mg/L chloride and set the sulfate ratio to r times that then you still have 2 degrees of freedom, x and r because y, the sulfate concentration, is just r*x. If, OTOH, you say I'm going to hold chloride between x0 and x1 and set the sulfate ratio to r then you no longer appear to have 2 full degrees of freedom as you have restricted x. Apologists for the use of the ratio often say, for example "Well, it works when the chloride and sulfate are modest." But there are still two degrees of freedom. You just used one up partially when you chose to restrict range.
Those who advise home brewers that they can make a malty beer by increasing chloride to sulfate ratio or a hoppy one by decreasing chloride to sulfate ratio do them a great disservice. One makes a malty beer by adding more malt and a hoppy one by adding more hops. Yes, the minerals do have an effect but they are relatively minor. This does not mean unimportant.
Where did the notion that the ratio was sufficient come from? I believe it was David G. Taylor's chapter "Water" in the Second Edition of Handbook of Brewing edited by Priest and Stewart (CRC Press 2006) in which he says:
"...these ions [sulfate, chloride] are somewhat antagonistic. In an attempt to quantify this point, it has been shown (Ref. 19) that increasing the Cl:SO4 ratio from 1:1 to 2:1 (on a mg/L basis) achieved increased taste panel scores for body and sweetness, with commensurate reduction in drying, bitter, and metallic flavors. In contrast, when the Cl:SO4 ratio was changed from 1:1 to 1:2, the increased sulfate content achieved reduced body and sweetness, but increased bitterness and drying flavors.
"These effects are repeatable at different absolute concentrations of chloride and sulfate. It appears that, in many cases, it is the relative ratio of the two ions that has the major flavor influence, often irrespective of the accompanying cations."
Ref 1: Taylor, D.G,. How water composition affects the taste of beer. Brew. Distill., Int., 11:35-37 1981
I think this to be the source as I started seeing the ratio touted as a design parameter shortly after its appearance.
My first observation is that dry and sweet in the sense of a champagne are definitely antipodal but are bitter and metallic in any sense antipodal to body and sweetness? Furthermore, is the 'dryness' occasioned by sulfate really a reduction in sweetness or a move towards astringency? Taylor himself says sulfate imparts "dryness/astringency". In a paragraph where here gives separate effect. I'll leave this to the readers to decide for themselves.
Now a question to the readership: Does anyone here really think that a beer brewed with 10 mg/L Cl- and 10 mg/L SO4-- is going to taste anything like a beer brewed with 200 mg/L of each? Or that if one goofs and winds up with a ratio of 4:1::SO4:Cl that he can fix the beer by quadrupling the chloride?
Going in we can add as much chloride or as much sulfate as we want to (within reason). We say, in such cases, that there are two degrees of freedom because we are free to set either wherever we want. If we assert that it is only necessary to know the ratio of SO4 to Cl then we no longer have two degrees of freedom but only 1. This is not saying that we still can't put as much of either as we want onto a brew but that it does not matter what the absolute amounts are; only what their ratio is. We all know that adding chloride sweetens the beer, rounds it and enhances its body. We also know that sulfate makes the bitterness harsher, drys the beer and adds metallic tastes (new one on me). Sounds like two degrees of freedom to me but again I'm encouraging people to evaluate this based on their own experiences.
Here's another point to consider. If you say I'm going to use x mg/L chloride and set the sulfate ratio to r times that then you still have 2 degrees of freedom, x and r because y, the sulfate concentration, is just r*x. If, OTOH, you say I'm going to hold chloride between x0 and x1 and set the sulfate ratio to r then you no longer appear to have 2 full degrees of freedom as you have restricted x. Apologists for the use of the ratio often say, for example "Well, it works when the chloride and sulfate are modest." But there are still two degrees of freedom. You just used one up partially when you chose to restrict range.
Those who advise home brewers that they can make a malty beer by increasing chloride to sulfate ratio or a hoppy one by decreasing chloride to sulfate ratio do them a great disservice. One makes a malty beer by adding more malt and a hoppy one by adding more hops. Yes, the minerals do have an effect but they are relatively minor. This does not mean unimportant.
