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Old 01-15-2017, 12:53 PM   #1
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Beef gravy: left over from joint roast

Greetings all,
A maiden post, so i hope i will start an interesting discussion.
I often roast beef joints, and always aim to make the richest-tasting gravy with the most depth of flavour. I am often left over with sauce from the roasting pan which i leave to cool in a tall clear pot for refrigeration. I find over night, it always separates into three layers: the golden coloured fat rises to the top and hardens; then there is a dark layer of 'jelly-like' substance, and then at the bottom, there is a layer of paler (tan-coloured) grittier paste-like substance. All melt nicely on the hob in a small pan. My questions:
i) what are each of the bottom two layers, and why do they separate?
ii) are there specific uses for each? clearly the fat can be used for potato roasting and making a roux for gravy, but what about the other two? is one more useful/flavourful than the other?
iii) with the layer of fat on top, how long can this all be kept in the fridge? i have ended up keeping the pot over a couple of months, and a small layer of mould will form on the fat...in which case i discard the fat and still make use of the (seemingly still fresh) layers below. i guess that's how things were preserved in the past....does anyone know how long such preservation safely lasts?
iv) roasting the meat in this stuff next time round, i often end up keeping the 'sauce' in a similar fashion, and the process repeats itself over and over. is this sensible, or do i end up taking health risks with many-times 'recycled' juices? in orther words, do i eventually need to throw it out and start again? or shouldn't i really use it all more than once or twice?

Many, many thanks for any thoughts on what i appreciate is a rather obscure and rather dull topic...!
John.

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Old 01-15-2017, 01:24 PM   #2
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Welcome to D.C., John.

Very interesting question. I'm interested in the answers as well.
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Old 01-15-2017, 01:35 PM   #3
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The gelatin is the rendered collagen from the connective tissues in the roast. It's almost pure protein. My home made chicken stock is almost all jelly when cold because I use the tip pieces from the wings, and they are about 50% collagen. It makes a very rich stock.

The bottom part sounds like the fatty solids (the empty fat cells) that are left after rendering the fats from the meat.
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Old 01-15-2017, 01:43 PM   #4
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First of all, if you're saving all this from the pan, what are you using to make gravy?

Top layer=fat
Middle layer=beef stock
bottom layer=solids from the roast

My routine with a roast (joint) is to use these three parts to make the gravy.

Remove the roast to a cutting board and cover it loosely with foil to rest for 20-30 minutes.

Skim off some of the fat from the pan and mix it with some flour.
Add some wine to the roasting pan and cook it over one or two burners (hobs), to remove any fond from the bottom of the roasting pan. Use a spoon or wood spate to hasten the process.
Whisk the flour/fat mixture into the liquid in the pan and stir to combine. Bring to a boil and adjust the thickness of the gravy with more flour or more liquid. Season to taste.
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Old 01-15-2017, 01:43 PM   #5
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Thank you Rick - that's insightful.

I'm generally heating each separately in small pans, and both seem to taste good with the finger-dip test, but are you saying it's the gelatin i should use for stock/gravy, and chuck the 'empty' fat cells? (currently i lob them both in)
And might you have any views on whether it can be safely recycled over and over?
thank you very much.
John
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Old 01-15-2017, 01:44 PM   #6
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Quote:
Originally Posted by john_coburg View Post
Greetings all,
A maiden post, so i hope i will start an interesting discussion.
I often roast beef joints, and always aim to make the richest-tasting gravy with the most depth of flavour. I am often left over with sauce from the roasting pan which i leave to cool in a tall clear pot for refrigeration. I find over night, it always separates into three layers: the golden coloured fat rises to the top and hardens; then there is a dark layer of 'jelly-like' substance, and then at the bottom, there is a layer of paler (tan-coloured) grittier paste-like substance. All melt nicely on the hob in a small pan. My questions:
i) what are each of the bottom two layers, and why do they separate?
ii) are there specific uses for each? clearly the fat can be used for potato roasting and making a roux for gravy, but what about the other two? is one more useful/flavourful than the other?
iii) with the layer of fat on top, how long can this all be kept in the fridge? i have ended up keeping the pot over a couple of months, and a small layer of mould will form on the fat...in which case i discard the fat and still make use of the (seemingly still fresh) layers below. i guess that's how things were preserved in the past....does anyone know how long such preservation safely lasts?
iv) roasting the meat in this stuff next time round, i often end up keeping the 'sauce' in a similar fashion, and the process repeats itself over and over. is this sensible, or do i end up taking health risks with many-times 'recycled' juices? in orther words, do i eventually need to throw it out and start again? or shouldn't i really use it all more than once or twice?

Many, many thanks for any thoughts on what i appreciate is a rather obscure and rather dull topic...!
John.
Hi, John. Welcome to Discuss Cooking

Let me preface this by saying that, for medical reasons, I've studied nutrition and food safety extensively and recently became a Master Food Volunteer, which involved a refresher on food safety. I've also studied food science just because I'm interested in it and how knowing it can improve my cooking.

i) what are each of the bottom two layers, and why do they separate?
the golden coloured fat rises to the top and hardens; then there is a dark layer of 'jelly-like' substance, and then at the bottom, there is a layer of paler (tan-coloured) grittier paste-like substance

The jelly-like substance is liquid with gelatin melted into it. Connective tissue, like tendons, are made of collagen; when this melts, at about 160F, it's called gelatin, the same stuff used to make Jello and sometimes to thicken sauces. It's usually used as part of a stock to make the liquid for soups and stews.

The stuff on the bottom is juices from the meat, along with fond (proteins that browned and stuck to the bottom of the pan) and bits of other tissues with some fat and gelatin emulsified into it. This is primarily flavoring for the sauce or soup or whatever else you make with it.

They separate because they have different densities, like oil and vinegar separate in a vinaigrette (unless you've added an emulsifier to help keep them together; roux acts as an emulsifier in a gravy).

ii) are there specific uses for each? clearly the fat can be used for potato roasting and making a roux for gravy, but what about the other two? is one more useful/flavourful than the other?

They're both useful in different ways: the gelatin adds body and a pleasant mouthfeel to soups, stews, sauces and gravies. The other part adds great flavor to the same. It can also be used in the liquid for a casserole or a rice dish, for example.

iii) with the layer of fat on top, how long can this all be kept in the fridge? i have ended up keeping the pot over a couple of months, and a small layer of mould will form on the fat...in which case i discard the fat and still make use of the (seemingly still fresh) layers below. i guess that's how things were preserved in the past....does anyone know how long such preservation safely lasts?

Foods were preserved that way in the past, and refrigeration helps, but it will eventually go bad. I have a really fun book called "The Good Old Days: They Were Terrible!" Dysentery and dehydration due to that were a huge problem before refrigeration became common.

It will not keep indefinitely and you may or may not be able to tell when it's gone bad. Especially if it's left out at room temperature for any length of time, pathogens will grow on it. Refrigeration slows down pathogen growth, but doesn't stop it altogether. Freezing does stop it altogether, so if you want to keep it longer than a week or two, I would definitely freeze it.

The thing is that, when pathogens grow, they produce a toxic byproduct which is not destroyed by heat. Your immune system will protect against a certain amount of that, but if there's enough, you can get very sick. People have even died of food poisoning.

iv) roasting the meat in this stuff next time round, i often end up keeping the 'sauce' in a similar fashion, and the process repeats itself over and over. is this sensible, or do i end up taking health risks with many-times 'recycled' juices? in orther words, do i eventually need to throw it out and start again? or shouldn't i really use it all more than once or twice?

You're taking a risk. As I said, if you don't use it up in a week or two, freeze it. Then you can thaw it and use it again. Repeated freezing and thawing will break down the texture, but, if it's refrigerated promptly after cooking, it will be safe.

Hope this helps.
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Old 01-15-2017, 01:47 PM   #7
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Quote:
Originally Posted by john_coburg View Post
I'm generally heating each separately in small pans, and both seem to taste good with the finger-dip test, but are you saying it's the gelatin i should use for stock/gravy, and chuck the 'empty' fat cells? (currently i lob them both in)
And might you have any views on whether it can be safely recycled over and over?
thank you very much.
John
You would use all the stuff in the pan to make the gravy. Fat plus flour makes a roux which will thicken the gravy. When you're done, you can strain out the solids. A properly made gravy should leave you with nothing to save for later.
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