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Messages - narcout

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Equipment and Software / Re: Orbital Shaker
« on: July 02, 2015, 08:00:35 PM »

Yeast and Fermentation / Re: Harvesting some yeast
« on: July 02, 2015, 09:18:33 AM »
Guess what happens if we serially repitch a starter versus serially repitching yeast cropped from a normal gravity beer?  If you guessed that the yeast culture loses vitality more rapidly, then you are correct.

If you are serially repitching, do some of the cells from the original generation stick around for subsequent fermentations?  At what point do the cells from the original generation die off to be replaced completely by newer cells? 

Actually, yeast cells consume O2 whenever it is available, which is why the "Don't rack to secondary because it will oxidize your beer" mantra is yet another home brewer created myth.

Is there a temperature below which they will stop consuming oxygen?

Classifieds / Re: Equipment wanted
« on: July 02, 2015, 09:08:56 AM »
If you want them, just PM me your address. 

I really don't want any money, I'd be happy enough if someone can put them to their intended use.

Extract/Partial Mash Brewing / Re: Trippin' about my dry hopped IPA
« on: June 30, 2015, 08:18:08 PM »
I think a wort chiller might be added soon, maybe a glass carboy. What would you recommend?

If you are doing a partial boil and topping off with room temperature filtered water (as you mentioned above), I bet you could avoid having to purchase a wort chiller if you chilled your top off water in the fridge.

You can use cheap rum or vodka for your airlock instead of Star San if it's foaming up and driving you nuts.

Ingredients / Re: Best Malt Brands
« on: June 30, 2015, 08:02:42 PM »
I've had good results with Castle (Belgian Pils).  I also like Simpsons for crystal malts.

Classifieds / Re: Equipment wanted
« on: June 30, 2015, 08:00:51 PM »
Glad to see you are going to be brewing again.  All I have to offer is a pair of faucets (the regular, chrome-plated, rear sealing kind).  Totally unused.  Free if you want them.

Equipment and Software / Re: Orbital Shaker
« on: June 30, 2015, 09:16:19 AM »
I found something interesting re agitation (though perhaps not conclusive):

"As can be seen from Fig. 1, the increase in agitation speed from 50 to 250 rpm led to an increase in biomass production (Fig. 1). This paralleled with the increase in the specific growth rate, sugar and nitrogen consumption and pH reduction (Fig. 2). However, the effect of increased mechanical agitation on the viability of Saccharomyces cerevisiae appears to be negative, with higher levels of dead cells present at the end of the cultures (Fig. 3).

Previous works [20] on the effect of mechanical agitation on the viability of yeast cells did not report cell damage at agitation speeds values higher than the maximum value used in the present study. Since in this work, the nutrients (carbon and nitrogen) consumption increased with increased agitation intensity (Fig1), this last variable is unlikely to have a physical effect on the growth of Saccharomyces cerevisiae.

Thus, the loss of viability observed at the end of the cultures could be due to the depletion of both carbon and nitrogen sources (Fig. 2) rather than to fluid-mechanical stresses caused by agitation [20]. However, the combination of both effects with the production of toxic metabolite (such as ethanol) may cause higher loss of viability than each factor alone."

Equipment and Software / Re: Orbital Shaker
« on: June 30, 2015, 08:42:13 AM »
Thought I would show pictures of my twins.


Can you describe your process (do you oxygenate or aerate the starters prior to using the shaker, how vigorous is the agitation, do you decant the supernatant, etc.)?

Equipment and Software / Re: Orbital Shaker
« on: June 29, 2015, 09:30:25 AM »
If the shaker continually aerates the starter, will you still pitch the entire thing rather than chilling and decanting the supernatant?

Equipment and Software / Re: Stir Plates
« on: June 29, 2015, 09:27:23 AM »
A stir plate provides inadequate aeration if operated at a speed low enough to prevent shear stress (perform a Google search using the terms "magnetic stirrer" and "shear stress"), and if operated at a speed high enough to add significant O2 to a culture results in shear stress being placed on the cells, which is why cultures that are stirred fast enough to create a vortex smell foul.

Is there any evidence that whatever shear stress might be placed on the yeast has detrimental effects on fermentation performance or the flavor of the resultant beer?

Physics prevents a culture in an Erlenmeyer flask from receiving O2 after it starts outgassing because gas pressure is highest at the mouth of the flask.

Whether or not stir plates provide any appreciable level of aeration (either before or during active fermentation in the starter) is a topic I have seen debated almost endlessly.  Are you aware of any studies on this issue?  I'd love to get a definitive answer; all I've ever seen is conjecture.

It doesn't seem like it would be a difficult experiment for someone with the proper equipment.

The Pub / Re: Homebrewing and Children
« on: June 28, 2015, 11:54:55 AM »
Congratulations, man.

Here are my thoughts:

I pretty much do the opposite, in that I brew in the evenings after the baby has gone to bed.  It does make for some late nights though.

Equipment and Software / Re: Orbital Shaker
« on: June 27, 2015, 03:26:35 PM »
Do you need a baffled flask to get the full effect?

I'd love to see a comparison (both cell counts and actual fermentation performance) among starters made on a stir plate, an orbital shaker, and shaken by hand across a variety of yeast strains, but I guess that would be a serious labor of love for the experimenter.

Very cool gadget, if you're able can you take a few seconds of video with a flask? I would love to see it in action!

Here is a really awesome YouTube video:

Equipment and Software / Re: Stir Plates
« on: June 27, 2015, 10:22:37 AM »
I think you will find better options than the ones you have linked to if you shop around.

Going Pro / Re: Start up funds?
« on: June 26, 2015, 05:02:11 PM »
Does any know of any other ways I could acquire the funds to purchase this business?

Maybe ask the seller if they are willing to take a note for part of the purchase price (fully amortizing or perhaps interest only with a balloon payment)?

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