beersmith predicts.

[mark_68]

I am going to attempt a partial mash at the middle of next month,so i experimented witha few recipes by running them through beersmith.When i clicked on "my mash" i picked heavy body,no mash out and after clicking ok it gave me a couple of temps. and a qty of water to add for the mash.There are a couple of things that i don't know though,does 76.9 celcius sound right to get strike temp. of 70 celcius. and will 45 mins. be enough time for the conversion?John palmers book states 68.3 celcius for heavy beers,so will beersmiths 70 be too high for the enzymes?

[Swifty]

I am by no means an expert as I've only done a handful of all-grains, but 76.9 sounds reasonable but I reckon it would result in a slightly lower temp, 45 minutes mash time I believe might be a minimum but you can do an iodine test to check the conversion has occured. 70 might be a bit high but should still work, I don't think you'd want to go any higher. I'd try and aim for more like the 68 degrees though.

[Trough Lolly]

I am going to attempt a partial mash at the middle of next month,so i experimented witha few recipes by running them through beersmith.When i clicked on "my mash" i picked heavy body,no mash out and after clicking ok it gave me a couple of temps. and a qty of water to add for the mash.There are a couple of things that i don't know though,does 76.9 celcius sound right to get strike temp. of 70 celcius. and will 45 mins. be enough time for the conversion?John palmers book states 68.3 celcius for heavy beers,so will beersmiths 70 be too high for the enzymes?

Firstly, a disclaimer - I use Promash not beersmith, so I'm not totally familiar with the beersmith interface etc. But 77C for a strike temp sounds in the park - the temp and volume indicated are based on the info you provide in the program (in Promash it's dilution (litres of mash water per kilo of grain) thermal mass of mashtun and grain temp).
Beersmith is saying add x gallons/litres of water at 76.9C in order to achieve a mash temp of 70C in the mashtun. Yes, you need to keep the mash liquor below 70C to avoid extracting tannins from the grain husks and between 60 and 70C there is a sizeable range that influences whether alpha or beta amylase enzymes will convert the grain starches into fermentable sugars. More on that here, if interested: http://www.chezwallis.com/pensans/processes_mashing.html
But the program is only as good as the info you've fed into it. I'd drop beersmith's mash temp down to 66C and redo your calcs. The thermal mass of your mashtun will absorb some of the heat before the grains go in, so beersmith will take into account that thermal mass and the starting temp of the grains (room temp normally) to determine how much water you need (usually expressed as litres per kilo of grain) and the resultant starting temp of the mash water so that by the time you've finished adding the grains, the mash will be at the desired temp (eg, 66C).
Hope this makes sense...
Cheers,
TL

[SpillsMostOfIt]

Where do you get all the good links from TroughLolly?

Palmer also has a discussion in How To Brew. If you want more fermentable sugars, your mash temp needs to be lower, but at the expense of thickness (and vice versa). I won't try to explain any better because there are others that do so very well.

I am told that hitting the right temperature will come with practice, but if you keep a kettle of near-boiling water handy, you can up the temperature a bit. I guess some very cold water would do the converse.

[Trough Lolly]

Where do you get all the good links from TroughLolly?

Palmer also has a discussion in How To Brew. If you want more fermentable sugars, your mash temp needs to be lower, but at the expense of thickness (and vice versa). I won't try to explain any better because there are others that do so very well.

I am told that hitting the right temperature will come with practice, but if you keep a kettle of near-boiling water handy, you can up the temperature a bit. I guess some very cold water would do the converse.

I've got heaps of bookmarked pages from many nights of web crawling!!

Yep, what you say is basically right re cool versus hot mash temps - and practice makes perfect. For beginning mashers, the best skill to acquire is temperature control - the current Aust Brewing Champion (in Canbeera of course!! ) is a big believer in temperature control. When I started mashing, I working on hitting 66C exactly for the first few beers and then once I had my procedure down pat, I varied it to suit the style of beer I'm making. 66C is a good sweet spot to balance the conversion of starches by alpha and beta amylase enzymes...

Cheers,
TL

[SpillsMostOfIt]

I really wanted to add something along the lines of:

"Computer says no."

[mark_68]

I finally found the infusion water temp. tool on beersmith and have started running some figures through it.Feeding 66 celcius into it as the step temp,i used 1 kilo as the mass of mash tun as i am using a 19 litre pot for my first partial mash.I will be adding 7.5 litres for the mash in,and i would guess the temp. of grain would be around 24 degrees.These figures gave me an infusion temp. of 71.5 celsius,does this sound about right?I am thinking that i might have to boil some water in one pot and also have a pot with cold water in it for adjusting temps.