On Fri, 03 Dec 2004 02:21:04 GMT, "Duke" > wrote:

snip
>
>Hello default,
>
>At risk of sounding like a complete idiot; how do you know your fermentation
>is complete without the use of a hydrometer ? And why wouldn't you want to
>know the alcohol content of a given beverage ?
>
>Duke
>
>
I'm using two stage fermentation in glass. Back in the days when I
thought I needed a hydrometer, it was always the same reading (given
the same type and amount of sugar and yeast) Unless I screw up,
fermentation is more than over in two weeks. At two weeks and onward,
I check the brew periodically for clarity (with a flashlight through
the carboy). If it isn't clear in two weeks I give it one more -

One batch in 20 may still be a little cloudy at three weeks - I bottle
it and "archive" it (put it on the bottom of the stack so it gets used
last).

I would want to know the alcohol content - but only if there were no
downside to learning. To "know" the alcohol content you have to have
an accurate idea of the SG going in - that is almost never accurate in
my setup. And you still don't know the alcohol - just the SG, from
that you calculate and assume to know the alcohol.

Once my equipment is sanitized, the yeast is pitched, the wort
aerated, I'm loath to open the fermenter for any reason. To my way of
thinking that just makes good sense.

If I were using a conical fermenter taking a sample wouldn't risk
contamination and I might do things differently.

Besides, I've done hundreds of batches in 14+ years. When
fermentation is over it is visible - no airlock bubbles (or one every
10+ minutes), clear liquid, no froth on top, no bubbles on the
surface, etc..

If I had the SG and it wasn't "right," I might worry - there's not
like there's much I can do about it. My goal is a satisfying brew,
the effects of alcohol are secondary to taste.

From my experience sanitation is important, ditto good yeast, well
started, good selection of hops, and then careful temperature control.
(mixing and aerating wort are second nature now). Get the technique
down and good beer is the result.

There are NO hydrometers in the labs - they do use them in the
chemical manufacturing plant - but only as a crude measure. The
closest thing we have in the labs is an instrument that sends a sample
into a loop of glass tubing and vibrates the tubing, from the
frequency of the vibrating tube they calculate the density of the
liquid. To measure sugar, we use an instrument that measures optical
rotation (the sugar twists the polarized light passed through the
sample). To measure alcohol the gas chromatographs, or liquid
chromatographs are probably the accurate ways. GC measures the
ability of the sample to affect the ions (electrical conductivity) of
a flame or nuclear source detector, LC measures the absorption of a
particular wavelength of light (mostly UV), both measure when (time)
the sample elutes from the column - a sort of resistance to the
movement of certain molecules over others, and the magnitude of the
absorption or ionization voltage.

Experience biases perception.

When all is said and done, a satisfying beer is what it is all about,
not the alcohol content.