From the HBD Archive
From: stcvax!rlr@hplabs.HP.COM (Roger Rose)
Subject: RE: 1. Slow yeast 2. White scum
Date: 1989-07-13 16:52:14 GMT

Chuck Ferguson writes:

> I had a some slow start on a batch of homebrew but I attributed it to
> the inability of the dry yeast to penetrate the foam barrier on the
> top of the wort. I could see the powdered yeast just sitting there.
> I was tempted to rouse or stir the wort in the fermenter but decided
> not to. It eventually took off and turned out OK.
>
> Nowadays I re-hydrate dried yeast with a cup or so of tap water prior
> to pitching. ...

Not stirring the wort is a potential cause of slow starts itself. The
boiling drives out the dissolved oxygen which is used by the yeast in
early fermentation. Stirring adds some oxygen back in. Of course the
faster the yeast takes over, the less chance of bacterial contamination,
but the more undesirable fusel's are produced. (Hopefully, the fusels
get broken down later.)

Anymore, I generally start my yeast in dextrose or malt ahead of time
to give it an opportunity to multiply. Malt is preferred, but a 1/4 cup
of dextrose in the yeast starter isn't enough to affect the flavor on
heavier beers.

Cheryl Feinstein writes:

> This is my first time including fruit in a wort. The recipe calls for one to
> boil up one's wort, cooking for 45 min, and then to pour 10lbs of cherries
> into the hot wort. This brings the temp down (hopefully) to 160-170 deg. F.,
> which one maintains for 15min. This pasteurizes the cherries. One is
> supposed to try not to let the temp get too high during this 15 min period, as
> there is the potential for bringing out the cherries' natural pectin,
> resulting in chill haze in the finished brew.
> ...
> This is where things started to get interesting. After racking into the
> secondary fermenting vessel (a glass jug) and putting the air lock on, I went
> out of town for the holiday weekend. When I returned, I discovered a white
> scum on the surface of the brew. The brew itself clarified nicely; the
> whatever-it-is is *only* on the surface. It seems to cling to the side of the
> jug; when I tipped the jug slightly it did so.

Fruit is always a trick since you can't boil it. You could of course use
sulfites in the same manner as wine makers.

As far as the "white scum", I'll venture a totally off-the-wall guess.
It is common practice to spray wax or some similar substance on apples to
make them nice and shiny for the store. Does anyone know for sure if
this is done to cherries?? (Just from looking at them, I'd suspect so.)

Roger Rose
UUCP: {ncar nbires}!stcvax!rlr
USnail: Storage Technology Corp. - MS1169 / Louisville, Co. 80028-1169
phone: (303) 673-6873

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