Malt Extraction Calculations

[JimJiminy]

I realise the answer to this is probably RDWHAHB, but this kinda thing bugs me...

I'm trying to understand the calculations relevant to the data on a malt analysis sheet. I'm using the data for Crisps Maris Otter as a test case, but I'm struggling to make sense of their numbers.

http://www.crispmalt.co/docs/Finest%20M ... 20Malt.pdf

They give:
Moisture: 3.5%
Typical extract:
308 °L/Kg
81.5%

Not sure if the latter figure is "% extract dry basis" or "% extract as is", but I can't make the figures add up either way:

Assuming "as is" basis, I think I should be able to just multiply the extract percent by the extract figure for sugar, to get the typical extract:
0.815 * 386 = 315

Assuming "dry basis", I think we correct for the moisture content as follows:
0.815 / (1+0.035) * 386 = 304

I don't understand why one these calculations doesn't give me the 308 value that Crisps provide.

I've seen a couple of websites mention a slightly different calculation:
((0.815 / (1+0.035))-0.002) * 386 = 303

But it also doesn't give the value I'm expecting. And I can't find any explanation of where the 0.002 number comes from.

Not sure if I am misunderstanding the theory and therefore doing the wrong calculation, or if I am misunderstanding the data from Crisps. Any ideas?

Regards,
Jim

[Cazamodo]

Not sure I can help with your calculations, as I'm too many beers in.

But I know I get a different LDK figure depending on the malt batch when Crisp deliver to me. They test it there and give me the specs dependant on that particular batchj of malt.

So if youre using a constant to work out the LDK it may well differ.

If that makes any sense at all.