CONFUSION re: EXTRACT BOIL TIME

I'm an extract brewer.  First post to this Forum...

I've had a few brews come out darker than expected, so I'm playing with recipe designs on Beersmith to try to understand the effect of the extract boil time on the outcome - using it like a simulator.

For a simplistic Kolsch, if I add a light LME with a boil time of 0, the bitterness is 20 IBUs, colour 3 SRM.
If I set the boil time to 1 minute the IBUs jump to 27.2, colour 3.
For 5 min I get 26.7
If I then go up in increments of 5 minutes the IBU decreases in a (roughly) straight-line until getting back to 20 IBUs at 60 minutes.
The colour stays constant at 3 SRM.

Intuitively (based on limited experience) I'd expect the colour to increase the longer the Liquid Extract is boiled, and I'd kinda expect the bitterness to do the same.  But this is not what Beersmith is telling me.

Is my intuition wrong (in which case I'm keen to be set right!) or could I be missing something in the way I use (or have set up) the software???

Can you tell us what you're recipe is to get the 20 IBUs? Also, are you starting with part of the extract and boiling it 60 minutes with a late addition of extract? A little more info can help us all diagnose what my be happening for you.

Beersmith has some quirks, so knowing a little more of your situation can help us determine if it is a software limitation or something with your procedure.

Darkening in extracts can be from old product (it darkens as it ages) or from maillard reactions. Neither of these factors is addressed by BeerSmith.

BeerSmith is pretty simple when it comes to color calculations. It uses the Morey equation.

This article should help explain it:
http://www.beersmith.com/Help/colors_tech.htm

SRM is a limited method for determining beer color. The correct way to evaluate it is at a depth of 1 cm.  The SRM method looks at how much of just one wave length is blocked.

From the above article:

Note, however, that the SRM/EBC color number is insufficient to determine the actual color.  For example, a beer with an SRM color of 5 brewed with a high proportion of Munich malt will have a decidedly red tint to it, while a beer brewed with pale and crystal malts with a 5 SRM color will appear straw colored.

Click to expand...

My method of determining color, isn't really much about color, as it is about how light or deep the shade of color is.  In my mind, SRM is not a way of judging the color of a beer, but is more about judging the darkness or lightness of a beer.  I think of it like this.  When only white and black colors are mixed together, you get a range of light to dark shades, anywhere from "almost white" to "dark black", with an infinite band of shades of grey between them.

In my mind, color is more of an art than science when it comes to homebrewing. 

For instance, when I want a beer to be red in color (such as my "Red IPA", I'll use some RedX malt and some Munich Malt) in addition to my base malt.  I might even through in a touch of 60L to 120L Crystal.

Brewing software, IMHO, does not do color well.  It will, however, get you in the ballpark on the depth of the color.

Thanks for the responses.
I need to separate my query into two parts;
Firstly, with actual brewing: Yes, I do now start the boil with just a little extract, boil the hops, then 10 minutes before the end I add the bulk of the extract - as per my understanding of Brad's 2008 article http://beersmith.com/blog/2008/02/20/better-beer-with-late-malt-extract-additions/ 
My boil volume is about half the target fermenter volume.  Results are better, but I now want to better model reality with Beersmith.
Intuitively the longer the boil time of the extract:  a)the darker the outcome? and b) the more bitter?  Does this ring true?

Secondly, my question is really about the correct way to use Beersmith 2 when designing a recipe.
brewfun referred me to http://www.beersmith.com/Help/colors_tech.htm and the Morey equation (Thanks, brewfun!)
The equation has no parameter for time, so Beersmith must account for this in some way extraneous to Morey.
To experiment virtually within Beersmith I've created a simplistic Kolsch recipe as follows:
23L brew (5 gal), reference style "Kolsch"
250 g Dextrose
40 g Tettnang.  Boil 45min
3000g Pilsen Light (Briess) 2 SRM  LME/CBW
1 pkg Kolsch Yeast (Wyeast Labs #2565)
Plug these in and the style bars show the Colour is a bit low at 3 SRM and also the Est ABV is only 4.6%, but near enough for this experiment.
(I hope this makes sense bigchicken)

Now, if you double click on the LME and set the Late Extract Boil Time to 0 minutes - and come back to the recipe screen - the Style Guide Comparison shows 20 IBUs and 3 SRM. (don't worry if you don't get my numbers, or use different units, kepp going and you should observe the sort of changes I describe here...)
Change the boil time to just 1 minute and we get a jump to 27.2 IBUs, but colour stays the same at 3 SRM
Keep increasing the boil time and the IBUs steadily DECREASE until reaching 20 at 60 minutes - colour constant at 3 SRM throughout.

So, it appears that Beersmith does not have a link between late extract boil time and colour???
And it appears Beersmith has an inverse relationship beween boil time and bitterness???

If I were a betting man I'd back Brad and Beersmith 2 over my intuition - so I suspect there is something else I need to know about using the software to address boil time.  This is my confusion!
I'd be keen to hear from anyone who either has been able to recreate the scenario described above, or can comment on the relationship between Late Extract Boil Time and a) Colour/darkness (I agree with Scott's comment on this) or b) bitterness.

Cheers!
AKA

AKA said:

my question is really about the correct way to use Beersmith 2 when designing a recipe.
<snip>
I suspect there is something else I need to know about using the software to address boil time. 

Click to expand...

It's interesting to throw unusual things at the software and see what breaks.

A proper comparison would be to look at the numbers from an all grain, full batch boil. This is what the calculations are made to reference. This is the most reliable, best and most classic method of brewing.

In that method, I see an SRM around 3 and an overall bitterness of 30 - 35 IBU.  So, that is now your reference standard.

By going into extract and partial sized boil, your numbers will be compromised because you've compromised the "classic best" scenario for brewing.

In late extract boiling, you're not getting much if any hot break. Most of that has been done when creating the extract. In an all malt wort, some amount of IBUs is lost to hot/cold break. In an extract batch with no hot break, that factor is removed. Longer boil times with extract will increase some hot break and BeerSmith appears to be taking that into consideration.

As for Wort darkening, BeerSmith strictly looks at the color of the ingredient in making that determination. Boil time has no effect because the heat source is not a consideration. Simply, there are just too many variables in heat sources, kettles and the rest of an individual system to reliably account for it. This is where you have to act as the brewer to understand what your circumstances are doing to the wort.