Chicken liver mousse, sous vide, astringent aftertaste

[adrianvm]

I've been making chicken liver mousse by frying some chicken livers.  I cook some shallots, deglaze the pan with port, reduce it, and then combine all of the above with butter in the food processor and strain it.  It seems like the results are kind of variable.  I believe this has to do with the step of cooking the livers.  Sometimes I get them more cooked, sometimes less.  The product often has a kind of gritty texture that some of my family don't like. 

 

In the recent posts on modernistcuisine they mentioned making chicken liver mouse by cooking the livers sous vide.  In fact, the chef who did this specifically noted the problem of improper cooking of the livers.  However, no information was given as to the temperature he used. 

 

So I cooked the livers at 131 F for 2 hours and then followed the procedure above.   The resulting product was extremely smooth.  But it had an astringent aftertaste that ruined the mousse.  In fact, I ended up throwing it away.  

 

This brought to mind a different chicken liver preparation I had tried in the past where raw chicken livers were pureed with eggs and butter and the mixture was cooked sous vide.  That product also had an astrigent taste. 

 

So I'm wondering where this astringent taste is coming from and what is necessary to eliminate it.  If I sous vide cook the livers at some higher temperature will I be able to get a result which is smooth, and has a flavor similar to the flavor I got when I pan fried the livers? 

 

 

[cdh]

Are you sure the bile glands were completely removed from the livers? Bile is bitter and astringent.

[adrianvm]

cdh, I think the livers were properly cleaned.  I get my livers from the same place and didn't do anything different than when I cook them normally, and normal cooking does not produce the astringent taste.  I observed the astrigent taste every time I cooked liver sous vide, which is 4 times, I think.  Is it possible that the bile is destroyed by high heat cooking but not by lower heat? 

 

CatPoet, it sounds like you're saying you blanch the livers before cooking them.  I have heard of this practice, though it's not clear what blanching is supposed to accomplish.  The best explanation I've seen is that it makes it easier to remove membranes, perhaps more of an issue with veal liver than chicken?  I have never done this and have always gotten good results (other than possibly issues with overcooking) by simply salting and pan frying livers.  

[CatPoet]

I have heard it makes for a smoother mousse / paté and well it works so I have kept doing it for  some 20 years now.

[Mjx]

Are you sure the bile glands were completely removed from the livers? Bile is bitter and astringent.

 

That was my thought, too; even a little bit of leaking bile can ruin the flavour. As far as I know, heat (high or low) does not soften the flavour of bile. Once it's in there, that's pretty much it.

[Kerry Beal]

I wonder if bile acid/bile alcohols might act like certain herbs in sous vide - their volatility in braises and other cooking methods might mean the astringent compounds cook out, while they may remain in the food in a sealed sous vide bag.  

 

I think you need to make a single batch - split in two and cook two ways to see if the astringency is only in the sous vide prep.

[adrianvm]

Actually now that you mention it, I have actually done that.  I had one package of livers that was fairly large, so I used one portion for my customary fried preparation, and it came out as usual with no astringent flavor.  I used the other portion for the experimental sous vide liver mouse where I combined the raw liver with eggs and butter in the blender and then cooked it sous vide.  And it developed the astrigent taste.

[nickrey]

I'd be exploring some other temperatures. 131F (55C) is much lower than the temperature that you would get with frying. I'd probably try 61C (142F). To cook and pasteurise to core would only take  36 minutes (thank you sous vide dash). A much shorter cooking time may decrease the likelihood of off flavours developing.

[CatPoet]

Maybe  this one of the things who doesnt get better by sous vide?   

[nickrey]

If the first try doesn't work, it is not a reason to discard the process.

[Kerry Beal]

Indeed - if we can figure out the compound that causes the astringency - perhaps adding something as simple as an acid or base might precipitate it out and take it out of the equation.

[adrianvm]

Well, I was inspired to use sous vide because Modernist Cuisine posted that they got a reliably smooth texture that way, and texture has been a problem when I fry them.  I asked Modernist Cuisine directly for advice and they suggest soaking the livers in salted milk over night to remove residual bile and blood before cooking at 60 C.  They thought that sous vide cooking does make the off flavors worse.