Cultured butter, anybody experienced with making it ?

Anybody experienced making cultured butter ?  I have a quart of raw cream that been in the fridge for 7 days . It was supposed to be made into sweet cream butter.  We did not  have (make)  time this week to do so...  I have been wanting to try to make cultured butter ... I do not know if 7 days in the fridge is to long David Asher says to long in the fridge causes unwanted bacteria... He does not say how long is too long ... Anybody Know ? This morning I removed it from the fridge and set it on the counter, thick on top but still smells just fine. I think i could still make sweet cream butter from it but.. if I leave it out overnight maybe it could be cultured butter??? Anybody done this before ? I don't want to make a batch of "bad ' cultured butter, even if it just tasted bad, the wife would never let me try again.  Help anyone ??

this is my favourite way to make butter (cultured and fresh).

Cultured Butter:
This is butter that is made with fermented milk.  I used a room temperature yoghurt culture called Fil Mjolk to culture the cream before churning it.  Cultured butter has a slightly sour flavour to it, but in a light and refreshing good way.  It's brimming with probiotic goodness and keeps a little longer than your regular butter.  It can be used the same way as normal butter for cooking, eating, baking, whatever.

So far as I can tell, this only works with Fil Mjolk or Piima - however, there may be other cultures that will make yummy butter.  If you find out what they are, please let me know.

Cream
Starter culture like Fil Mjolk or Piima
salt (optional, but a good idea)

The day (or two) before you want to make butter, culture the cream as per normal.  I use the Fil Mjolk, so I'll describe my method.  When you make it, follow the instructions that come with your culture.
Add 1 Tbs of culture per cup of cream (4 cups in a litre).  Stir it well into the cream and cover with a cloth.  Leave at room temperature for 10 to 20 hours until the cream has set into a firm yoghurt-like consistency.  
Place the cultured cream into the fridge for at least 6 hours.
Remove starter for your next batch, then put the rest of the cultured cream into your butter churn and follow the instructions as per making regular butter above (churn, wash, salt, press, store)

Since that was written, I'm a bit less attached to my fil mjolk starter culture.  I think raw cream would work well without a starter.  I'm also thinking kefir would make a nice starter.

David Asher says to long in the fridge causes unwanted bacteria

I'm wondering this too.  If it's been airtight all that time, I don't think it's going to be a huge problem... but I'm still learning about raw milk.  The nice thing about milk is that it likes to tell you when it's gone off.  If I was in your situation I would try one of three things (or all of them) and see how it goes.

make normal butter with the cream as is and make cultured butter next time (call it butter making practice)

use a starter culture like fil mjolk or kefir

go for it.  Leave the cream at room temp overnight and churn away.  

I personally don't think a week is too long so long as there hasn't been much air at the cream.  However, there is so little info about raw milk and how to keep it safe with our modern methods of storing food that I just don't know.  

Decided to turn it into sweet cream butter.  Never having tried cultured butter before we decided that we would not know if it tasted rite or wrong. So we made it into sweet cream...it came out fine . Next week I may try culturing some fresher cream into butter. Many thanks for the your information !

Please let us know how it goes.

for cultured butter - all we do is:
leave a quart of cream on the counter for 24 hours, then make butter.
we have noticed that room temp cream and a cold bowl makes the butter break faster.

we having ever tasted anything off - though i can say cream doesnt usually last a week at our house

My wife and I have made cultured butter with both just raw milk cream and with raw milk cream treated with kefir.  Both are awesome, but I think we prefer the cultured butter made with kefir.  Hard to describe, but the kefir cultured butter has a richer flavor.

We've never had a problem using week old raw cream to make butter, or drinking the raw milk that is that old.  I like leaving the cream out for the better part of a day, it seems to break quicker.  I've made cultured butter just by leaving the cream our for a day or so and processing as normal.  Leave it a little longer and you've got the best sour cream you can imagine!  All from the naturally occurring bacteria already present in the milk....crazy right!?!?  

How would somebody know if the cream becomes dangerous while culturing?

Also, crazy idea (probably needs iteration and testing) what would pine needle, spruce tip, juniper berry cultured cream/butter be like and would it be safe? What about lavender?