Understanding adding LME or DME late in the boil?

I have another beginner’s question: I’ve been reading some threads that advise adding LME or DME late in the boil to improve the taste and color of extract kit beers, contrary to most kit instructions. So, do you add 1/2 the extract at the beginning of the boil and the remainder of the extract near the end of the boil? Or add all the extract at the end of the boil or flame-out? By doing this, aren’t you just boiling hops and a weak, tea-like wort from the steeping grains? And, so there is no need to full boil the extract?

When I did extract, I put half the extract in the boil and the rest at flame out. Never had an issue doing it that way.

Kit instructions usually say boil the extract from the beginning. With a full-boil hop addition, extract helps smooth out the taste of the hops. You can add 1/4 of the extract to help with the hop balance. It can also be added late boil, but I personally wouldn't wait until flameout. I want it to be in the boil long enough to sterilize it (~15 min.) and get it to assimilate into the wort. While a full-boil extract addition causes more darkening, a late-boil addition can make the beer slightly more bitter since there won't be as much time for the oils to boil off. You'll have to find your balance. Either way, you want to add extract slowly and stir constantly to avoid scorching on the bottom.

I have only brewed three batches all kits but i think the point is to cook out the sugars very well so the yeast can easily digest them. I would strictly follow the recipe and schedule. These processes arise from a craft that dates back to B.C.

When I was stove top cooking a lighter color beer I would do about 1/3 for full boil and rest near flameout so the extract would not darken. Now that I have gone to full boil, I add it all in and have never had an issue.

kylieWylie said:

I have only brewed three batches all kits but i think the point is to cook out the sugars very well so the yeast can easily digest them. I would strictly follow the recipe and schedule. These processes arise from a craft that dates back to B.C.

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Actually, the reverse is true. Cooking the extract for lengthy periods of time creates excess maillard reactions (similar to caramelization type of reactions). It makes the extract's sugars less fermentable.

The brewing craft does go back many eras, but the rise of malt extract is very modern. Since the extract is already processed at the manufacturer, it doesn't need to "cook" more. Boiling it darkens it and creates a "cooked extract" taste as well as creates some less fermentable sugars.

Many kit makers now recognize that, and often newer company directions will state to use about 1 pound of extract in the boil per gallon of liquid, with the rest of the extract added late in the boil or at flame out.

If you are boiling the full-volume of wort (5 or 6 gallons) then you are fine to add it right at the beginning. However, if you're doing a smaller boil and will be topping off with water, then you may want to save half of the extract for the end (10m before end-of-boil).

Just to add to the conversation, I add the remaining extract in AE or E/SG brews @ flame out. Why is this ok to do? Because pasteurization happens in seconds @ 160F, & the wort is still boiling hot. Never had a problem wit flame out additions.
Having said that, now that I'm into PB/PM BIAB, my mashes are getting big enough- 4-8lbs+- that I can use that for the boil & add the couple pounds of extract at flame out.
But, with E/SG brews (Extract/Steeping Grains), it'll depend on how many pounds of grains you're steeping as to the gravity of the wort being sufficient for the boil. With the steeped wort, you may more often as not have to add about 2lbs of extract for the boil.