Birdwatchers, a hat tip and a dissection.

[bastardsquad]

Hi all, BW was the first non turbo I ran and is likely the wash that kept me in the hobby. All credit to the BW, and reading(most of) the voluminous thread, one can see the evolution of the recipe and methodology. It's simplicity is it's genius, and as such , this is what has me thinking.....

Threads I see where BW is problematic generally strike me as being nutritionally related, as the typical lament seems to be slowed ferments after an initial vigorous/promising looking ferment. One could surmise pH is at play similar to the "why has my gen 5 UJSSM slowed?" type thread. - however yeasts happily ferment at 23 brix in the 3.0-3.5 range in wine(low pH is due to large amounts of tartaric and malic acid in high brix musts), so I can't accept low pH as a significant contributor.

If we break BW recipe down, it's sugar, water, tomato paste (as a yeast nutrient), lemon juice(to lower pH) and yeast - in essence the basics to support a healthy ferment. BW recipe has a large yeast inoculum size, and a fairly high ferment temperature, so it's likely to be a rapid and ravenous beast??

However, the feedback varies.

I put down a 170L BW tonight, and I usually do mine at about 1.06 ish with around the recommended Tomato add, plus the revision of a small amount of Mag Sulphate (2 heaped teaspoons for me), citric acid to adjust my rainwater (about 5 heaped teaspoons) and a reasonable addition of DAP (around 5 heaped teaspoons). Yeast is generic bakers, rehydrated/starter for an hour or so until high krausen(about 20-40 mins without stirring/oxygenation) then poured onto the top of the fermenter where oxygen loving bakers yeast loves to be - normally use about 30 g dried yeast to inoculate the starter. Fairly generic yes. Ferment temp about 25C, not racing at all. Aim for about 9% ABV in the wash, final SG dependent.

So. Here's where i'm wondering. Yeast need Nitrogen in the ferment to do their thing, without stressing (= slowing, producing off flavour/smell + other issues). Birdwatchers only N source is in the tom paste or added DAP/DAP equivalent eg fermaid. General wisdom in the wine industry is to add DAP about 1/3 way through ferment, not at the start - as the yeast will metabolise the available Nitrogen in the must first, then when it starts to show stress (smelly sulphide aromas in the ferment), add DAP as a remedy. Adding DAP at the start is like giving children sugar - sure they can eat it, but they will leave the veges behind and eat the sugar first, run around like mad , and generally cause havoc!

In theory, the required amount of Nitrogen Available to the Yeast (YAN) in the must (and therefore the deficit which needs to be added for a successful ferment!!) is known for most starting brix/SG's for wine must. A generic wash cant be too far away in nutritional requirement?

Do we know how much N is available in tomato paste? Similarly, if it isn't enough, do we know how much N substitute to add to keep the yeast happy?

BW takes off like a rocket typically, but does slow , about mid ferment - which is what makes me wonder....when I use the online wine industry calculators for YAN, are we starving our BW ferments ?

Be interested in your experience with DAP and feedback.

[rad14701]

My Birdwatchers washes don't slow down because I add 30-10-10 to the recipe at a rate of 1/2 teaspoon per gallon... No, it won't poison you... No, it doesn't add any off flavors... No, it doesn't carry over into your spirits... It just works, like it does for your flowers and vegetables... You just wouldn't want to drink a couple glasses of the wash or you'd might spend some time on the toilet due to diarrhea...

[bastardsquad]

That's a helluva NPK ratio for your lawn fert addition : O. Know what you mean about 'salts' and bowel evacuation , colonoscopy anyone?



http://www.nanaimowinemakers.org/Steps/ ... trogen.htm" onclick="window.open(this.href);return false;" rel="nofollow

These guys dial in the N requirements of a few yeasts and detail the %N of some common additives. For the low brix 'must' we ferment as a wash , 1 g/L DAP addition @ 21% N would seem right, but most of us are well below this? Is the Tom paste doing all the rest, or are we short?

[drinkingdog]

As you can see by Rads avatar he knows what he's talking about drinking to much of the wash. Question for Rad. I thought you used 20-20-20 for everything. Is it just BW you use 30-10-10 or have you switched to it for every recipe that you add fertilizer?

[Beerbrewer]

I just use the traditional recipe and it ferments well below the 1010 mark within a week, aeration is my main concern, I'll leave an air stone in the wash for an hour or so and never had any problems with a stalling ferment.