originally posted by SFJoe:
The overlap in iron content between white and red wines is apparently quite large.
But generally white wines have higher acidity which has a chelating effect thereby modifying the effect of the iron.
Perhaps I have mis-read this and the other thread but the article didn't seem to me to be pronouncing on whether red wine could or couldn't taste good with fish [which some certainly can particularly for fish like salmon and tuna et al] but was seeking to provide an alternative rationale for why the [now generally ignored] rule of thumb which indicated that most red wine and fish don't work well together might have come about.
The choice of any wine with fish is also highly likely to be affected by what the fish is cooked in and/or with.
The 'old' rationale' was the tannin in red wine which is largely absent in white was the cause and basis of the formulation of that 'rule of thumb'.
Their 'new' explanation was that an unpleasant 'fishy' reaction with wine seemed to correlate strongly with the presence of iron [from whatever source] AND a [relatively] low acid environment - which, they implied, was considerably more likely to occur with red rather than white wine.
This seems a perfectly feasible conclusion from the tests they described and doesn't require that white wines will ALWAYS have less iron then red wine although it is probably fair to say that, for their hypothesis to hold, red wines should generally have a significant iron content AND [perhaps more importantly] generally lower acidity than white wines.
Of course if the iron content of a large sample of red and white wines was known together with their acidities it would provide an intuitive basis for support for or scepticism about the new idea.
As far as Humagne Blanche is concerned it may, as reported, have a high iron content but without knowing what it is one cannot compare it with levels found more generally in red wines and there was nothing about its acidity which might of course also be high.
Perhaps Thor could help here since he posted on Savioz Clos Chateau Ravire 2000 Humagne Blanche in February 2007.
More importantly I cannot see any assertion in the [very summarised] report that no white wine would ever have a high iron content. I also note from some posts that the soils of Rueda have a high iron content and would be interested to know if the wines of Rueda have the same characteristic.
Even if they do it does not necessarily provide a point of contradiction to the report without a study of the acidity and its performance with fish. As far as the latter is concerned I can confirm that I have drunk [white] Rueda wine with fish and enjoyed the experience.
Without more information it is difficult to form a definitive view but equally I see nothing obviously faulty with their science or their conclusions and I also recognise that the opinions expressed about matching red wine and fish and the possible difficulty of changing attitudes viz the last paragraph came from the journalist not the researchers.