Magnetic Stir Plate

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bobsbeer

Magnetic Stir Plate

Post by bobsbeer » Fri Aug 18, 2017 4:34 pm

Just seen this new Stirrer on Heaven Gifts - https://www.heavengifts.com/product/Nit ... Mixer.html. Looks like a decent bit of kit for those who culture their own yeast. Reasonably priced for what it is at around £100. Nitecore are a reputable manufacturer of battery chargers, but not seen this before. This is aimed at vaping people, but the brewing application is what interests me.

Image

Product Introduction
As an advanced liquid mixer specially-designed for vapors, the Nitecore NFF01 Magnetic Liquid Mixer is a professional device. Users will be able to enjoy the mixture of e-juice for massive clouds and optimal flavors as they wish. It adopts an adjustable rotational speed from 70 to 1200 revolutions per minute.

The heating temperature is selectable between 35 to 70℃. The most important feature is the intelligent mixing mode: PMM and SMM, to suit your desired mixing needs. The simple user interface shows all the data in a clear and easy way. EURO Plug and US Plug for your selection.

Parameters
Size: 161 x l44.7 x 53mm
Input: DC 12V 3A MAX (a power adapter included)
Motor: 70-1200 R.P.M. (displayed on the screen)
Motor output: 3W
Heat output: 30W
Heating temperature: 70℃ MAX
Temperature control: Digital temperature control
Control precision: 5℃/10℉
Heat source: Ceramic
Panel material: SS304 Stainless steel
Mixing capacity: 30-1000ML (30-200ML recommended)
Operating duration: SMM default mode: continuous, PMM programmed mode: 14 days (maximum duration)

It comes with
1 x Nitecore NFF01 Liquid Mixer
1 x Power Adapter
1 x Stir Bar
1 x A Magnetic Rod

HairyJamie
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Re: Magnetic Stir Plate

Post by HairyJamie » Fri Aug 18, 2017 6:16 pm

What a strange product? I'm a vaper and have never heard of anyone continually stirring their juice ? A quick shake does me (ooer missus).

Is 35° c too high for a starter?

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chris2012
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Re: Magnetic Stir Plate

Post by chris2012 » Fri Aug 18, 2017 6:55 pm

I could be wrong but I think you're right, from what I recall I thought ~31C is the optimal temp for yeasties to grow (ignoring the fact that you will get unwanted esters likely at that temp, but I assume for a starter that doesn't matter too much?)

Edit: just found this
http://www.brewmart.com.au/brewmart-sho ... growth.pdf

guypettigrew
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Re: Magnetic Stir Plate

Post by guypettigrew » Fri Aug 18, 2017 6:58 pm

I thought we were supposed to shake, not stir!

Earlier posts have suggested stirring is bad for the yeast cells.

Guy

chris2012
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Re: Magnetic Stir Plate

Post by chris2012 » Fri Aug 18, 2017 6:59 pm

Intriguing, I've not heard that before, do you know why that is, as lots of people
seem to use magnetic stirrers.

Edit: http://braukaiser.com/blog/blog/2013/03 ... st-growth/ Just looking at that, it would be nice to see something
similar for an orbital shaker.

Regarding stir plates, doing some skim reading, are you talking about 'shear stress', does that result in yeast death, if so I wonder if there are any experiments with methylene blue + hemocytometer of both methods, to compare health.

McMullan

Re: Magnetic Stir Plate

Post by McMullan » Fri Aug 18, 2017 8:33 pm

Stirring yeast starters is absolutely fine, if you have a stirplate. (I'm not recommending this one.) Around 30*C is optimal for yeast growth. Don't worry about esters. It's a culture, not a fermentation. Room temperature is fine too. And the shaken-not-stirred method works as well. Horses for courses, as they say.

guypettigrew
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Re: Magnetic Stir Plate

Post by guypettigrew » Sat Aug 19, 2017 4:45 pm

chris2012 wrote:
Fri Aug 18, 2017 6:59 pm
Intriguing, I've not heard that before, do you know why that is, as lots of people
seem to use magnetic stirrers.
Here's a link to the original post about shaking rather than stirring. Seems stirring can break up the yeast cells.

Guy

McMullan

Re: Magnetic Stir Plate

Post by McMullan » Sat Aug 19, 2017 5:19 pm

guypettigrew wrote:
Sat Aug 19, 2017 4:45 pm
Seems stirring can break up the yeast cells.
:^o So Please explain why no one has reported fermentation issues after stirring yeast starters? The stir plate is widely used by home brewers and scientists in labs. I have assessed this myself and I found no evidence of yeast cells 'breaking up'. So called shear stress is an issue for fragile mammalian cell types, not yeast cells. Your ignorance propagates myth [-X That's not to say the shaken-not-stirred method doesn't work, it does; but stirring promotes more population growth sooner.

guypettigrew
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Re: Magnetic Stir Plate

Post by guypettigrew » Sat Aug 19, 2017 7:00 pm

McMullan wrote:
Sat Aug 19, 2017 5:19 pm
:^o So Please explain why no one has reported fermentation issues after stirring yeast starters? The stir plate is widely used by home brewers and scientists in labs. I have assessed this myself and I found no evidence of yeast cells 'breaking up'. So called shear stress is an issue for fragile mammalian cell types, not yeast cells. Your ignorance propagates myth [-X That's not to say the shaken-not-stirred method doesn't work, it does; but stirring promotes more population growth sooner.

Hey, don't get aggressive!!

I just linked to the thread I'd read ages ago by Yeast Whisperer in which he suggested shaking was better than stirring. It's of no real relevance to me as I harvest my White Labs yeast for about 3 brews, use it without making up a starter, then buy a new yeast.

Just thought the thread was worth reading through again for people who want to make up starters.

Guy

McMullan

Re: Magnetic Stir Plate

Post by McMullan » Sat Aug 19, 2017 7:16 pm

You stated 'stirring can break up yeast cells'. It doesn't. Even if yeast cells are centrifuged, they won't break up! The linked thread is interesting, as it is, without fake statements being added. 'Aggressive' or intolerant of bullshit? The latter me thinks :D

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Re: Magnetic Stir Plate

Post by guypettigrew » Sat Aug 19, 2017 7:32 pm

Apologies, I thought this bit in the post meant the yeast cells would break up if a stir plate was used. " Additionally, spinning a starter fast enough to aerate the medium during the lag phase causes the yeast cells to experience shear stress, which is why stirred starters often smell and taste foul."

And who the f*#@k are you to accuse me of bullshit?

This is a friendly site. Or always has been. Why are you getting so aggressive about my posting link to another post?

I've never used a stir plate, never intend to and just posted to try to be helpful.

Perhaps you should take a deep breath and recover your equilibrium.

Guy

McMullan

Re: Magnetic Stir Plate

Post by McMullan » Sat Aug 19, 2017 7:42 pm

Remind me who is getting aggressive here :D Then find me some evidence that stirring yeast is bad. If you put a filtered beer on a stirplate for a day or two, it's going to smell and taste foul. Any idea why that might be so?

guypettigrew
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Re: Magnetic Stir Plate

Post by guypettigrew » Sat Aug 19, 2017 7:57 pm

No idea--ask yeast whisperer. He wrote the OP

Guy

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thickodicko
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Re: Magnetic Stir Plate

Post by thickodicko » Sat Aug 19, 2017 10:42 pm

guypettigrew wrote:No idea--ask yeast whisperer. He wrote the OP

Guy
Image made me wake the Mrs up chuckling.

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Sadfield
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Re: Magnetic Stir Plate

Post by Sadfield » Sat Aug 19, 2017 11:45 pm

I think the point about stirring vs shaking was in regards to oxygenation, with shaking being better as stir plates were not designed to aerate, but to keep a substance in suspension. The lack of aeration can cause starters to have off flavours. I think the shear stress thing was added on to the argument to add weight to the shaken not stirred idea. £100 stir plate and £25 flask vs a 5L spring water bottle, I know which method I prefer.

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