I have never had this problem, but I'm interested in the recipe you are using... care to share?

Sounds like simple oxidation to me. I make pea soup all the time without this issue but I never make it in the slow cooker. Adding some lemon juice instead of some of the water might help reduce oxidation.

does it turn brown or greenish-brown? i find that split pea soups don't stay a bright green when they cook. the green in the picture above (not sure if its yours) seems the right color for a split pea soup.

with that said... i sometimes cheat and throw in a handful of fresh peas (or frozen ones) if i'm trying to piece together a beautiful meal with bright colors. i do it near the end or when i puree it.

Are you including carrots? I ALWAYS do, and the carrots, when cooked very thoroughly, contribute to a brown pea soup. It doesn't bother me, because it still tastes delicious.

I say embrace the brownish color by selecting yellow split peas instead of green, for a pretty golden porridge. Also consider a spoonful of chipotle peppers in adobo... they REALLY turn it brown, but taste so good you won't care.

What colour peas are you using - green or yellow?

I always use carrots and yellow peas, and my soup stays yellow in colour

Hi Rosie, would you be able to tell us what other ingredients you're using? I make split pea soup in the crock pot fairly often and I've never had this problem. I also always use carrots in my split pea soup - sometimes sliced, sometimes grated - and I've still never had the soup turn out brown. I'm curious to know what could be causing this to happen. Hopefully we can figure it out for you, but the good news is that it still tastes yummy. :)

Mine usually turns brown-ish, but I wouldn't call it brown. I've used both green and yellow split peas.

@Duckalucky: the chipotles sound like a great addition. I love them and I love pea soup, so thanks for the idea.

For those interested in the recipe I use:
1lb split peas
6 C water
1 carrot, finely chopped
2 ribs celery, finely chopped
1/2 C finely chopped onion
1 bay leaf
1 t paprika, preferably smoked
1/2 t cayenne pepper
1 C diced ham, 2 ham hocks or 1 meaty ham bone
Ground pepper, to taste (you likely won't need salt because of the ham)

Toss everything into a 4 quart slow cooker and cook for about 4 hours on high or 8 on low, or until the peas lose their structure and the soup thickens. I've also seen people add a diced potato or two.

Oh, and clearly you'd remove the bay leaf once the soup is cooked.

I would have guessed that the long cooking in the crock pot would be the cause of the color turning. Obviously it's not if other people are cooking in the crockpot and retaining the green color.

Are you adding any acid to the soup? Acids such as vinegar, wine or lemon juice will turn veggies from green to murky if you add them at the beginning of the cooking process. So if you are adding any acidic ingredients, wait til you get home.

Now guess who's hungry for pea soup?

Thanks for all the great suggestions. My recipe is fairly straightforward: carrots, celery, onion (all diced)-1 cup of split peas and then water or broth. Sometimes I'll add a ham hock but not always.

Thanks again!

I'm thinking maybe there's tomato in the broth? This could be the acidic component that is turning the soup a murky color. Does it come out the same when you use just water compared to when you use broth?

Is your slow cooker have a metallic insert or the porcelain insert?

Mine looks like the one in the picture and i add onions, carrots, garlic and cut up corned beef or left over ham. I don't usually stick a bome in it though.

Mine is brownish on the slow cooker and bright green on the stovetop, so I think it is the long cooking time. Lemon juice will help, but it alters flavor in a way I'm not fond of. You could try soaking the peas overnight beforehand and cooking them for less time.

I use the slow cooker for pea soup all the time (we love it over here-often once a week!). My recipe is almost identical to yours with the exception that I add barley. Six hours on low is always enough for my pot...and I cook VAST amounts at a time. I'm talking two entire bags of peas, 8 chopped carrots, two chopped onions, 3 cooking spoons of garlic and enough broth to cover the mound by a half inch. The only time it's ever turned brown on me was when I cooked it overnight and then left it on warm for the day while we were out. So I'm inclined to think it's the long cook time that's doing it, especially since you're cooking so much less at a time. I'd guess maybe 2-3 hours on low? That's what it takes on my Mom's stovetop (also on low heat).

Good LUck!

I never have a problem with brown split pea soup, but I don't use a slow cooker. It really only takes an hour or so to cook on the stove.

Well, I think you should reduce cooking time by soaking the peas overnight in cold water.

The original recipe (from a 1960 cookbook by Latvian authors, the amounts are oddly given per person):
400g water
100g smoked pork
25g chopped vegetables
10g barley corns
40g peas
herbs & spices (spice, pepper, salt, laurel/bay leaf)

First bring the meat to boil, then add chopped vegetables, soaked peas & barley and boil until everything is done. (Boil the meat in one piece. When soup is done take out the meat, chop it into sensible small pieces and put it back. You can also use cheaper pork products like smoked legs & skin part when boiling to give the smoky taste & aroma, just don't put them back before serving.)

My modifications:
1. I as a lacto-vegetarian omit smoked pork, but include some butter (100g or less for a 5litre pot) in the end of the boiling
2. I also use some vegetable stock instead of plain water
3. I use yellow split peas and let them soak in cold water overnight
4. I use either whole or chopped barley corns. When whole I soak overnight, when chopped then about an hour or so.
5. I only use carrots and onions and add them later than the peas.
6. It takes about 2 hours or so on a regular gas stove when the peas have been soaked before. I've used regular enamel & stainless steel pots.