Keeping left-over pan sauces longer? Am getting sick of adding the wine, then waiting for it to reduce, then adding the broth and waiting for it to reduce, and then adding the butter and waiting for it to do its job thickening...

Actually instead of wine I'm using vermouth because it lasts longer in the fridge.  And I'm using a whole milk/corn starch slurry instead of butter because it's lower in fat.  But above is the general idea.

So, noticing a bottle of barbecue sauce in my fridge and how easy that is to use, I'm now looking for guidelines on how long I can keep pan sauces I make this way, any tips on how to prepare them so they last longer in the fridge?

Barbecue sauce has vinegar in it, that because of it's acidity, is supposed to make that sauce last longer.  But my pan sauces have wine in them that should help longevity?

I know Wikipedia is no expert on cooking, but I noticed on the demi-glace page they claim that stuff lasts 6 months in the fridge or almost indefinitely frozen.  It can't possibly last that long, can it?
First thing to try is freezing, possibly in ice cube trays (once frozen, transfer to freezer bag). Freezing has the advantage that you can be confident the food is still safe to consume.

Unfortunately, cornstarch-thickened sauces often don't hold up to freezing. A couple of approaches:


Thicken only after thawing. Takes more time reheating, but not much.
Try arrowroot or tapioca starch. You'll get a different look and slightly different texture than you're used to.
Use "modernist" ingredients for thickening, such as guar gum and/or xanthan gum. The texture is probably going to be different than what you're used to.


Your BBQ sauce is not only low-pH it is also high-sugar. Both reduce microbial growth. It'd be difficult to know how long your pan sauce would last in the fridge without measuring those, and possibly doing lab work.