How to Make Stock From Kitchen Scraps for Free

A one-litre carton of supermarket stock costs somewhere between 2 and 4 dollars, and most home cooks get through two or three a month. Meanwhile the onion skins, carrot ends and chicken bones that could have made that stock go straight into the bin. Learning to make stock from kitchen scraps is one of the few budget moves that saves money without asking you to eat anything less good.

I have kept a scrap bag in my freezer for about eight years. It fills in roughly ten days, becomes three litres of stock on a Sunday afternoon, and costs me nothing except the gas or electricity to simmer it. Here is the system, including what to leave out, because a bad scrap bag makes bitter, muddy stock.

Start a Freezer Scrap Bag

The whole method rests on one habit: a large zip bag or a lidded tub in the freezer, labelled, that gets every useful trimming as you cook. Freezing stops scraps from going off, so you can collect slowly over a week or two instead of needing a full pot of vegetables at once.

Keep two containers if you cook meat: one for vegetable trimmings, one for bones and carcasses. That way you can make a vegetable stock for a lentil soup and a richer chicken stock for risotto, rather than one muddled version.

What Goes In and What Stays Out

Not every scrap belongs in the pot. Brassicas turn stock sulphurous, and some peels add bitterness that no amount of salt fixes.

Onion skins are the secret ingredient most people throw away. They give stock a deep golden colour that looks like hours of roasting.

Bones Are Where the Body Comes From

Vegetable scraps give flavour; bones give body. A roast chicken carcass, the wing tips you trimmed, the bone from a pork shoulder: all of it goes into the bone bag. If you already follow the habit of turning a roast chicken into several dinners, the carcass at the end is your free stock base.

Two chicken carcasses plus a bag of vegetable trimmings make about three litres of good stock. Add a couple of raw wings, which cost very little, if you want stock that sets to a light jelly in the fridge.

The Basic Method, Step by Step

1. Load the pot. Tip frozen scraps straight into a large pot. No need to thaw.
2. Cover with cold water. Use about 3 to 4 litres for a full bag, enough to cover by 3 cm.
3. Bring up slowly. Heat until a few bubbles break the surface, then turn it down.
4. Simmer gently. One hour for vegetable stock, three to four hours for chicken bones. Never let it boil hard.
5. Strain. Pour through a sieve lined with a clean cloth if you want it clear.
6. Cool fast. Set the pot in a sink of cold water, then refrigerate within two hours.

Do not salt the stock. You will reduce it later or use it in dishes that are seasoned separately, and salted stock becomes too salty once concentrated.

Why Longer Simmering Is Not Always Better

Plenty of advice says the longer you simmer, the better the stock. For bones, there is some truth to it, up to a point. For vegetables, it is wrong.

Vegetable scraps give up most of their flavour within 45 to 60 minutes. After that, carrots go flat and onion skins and herb stems start pulling bitterness into the liquid. I tested this once with the same bag split into two pots: the one-hour stock tasted bright and sweet, the three-hour one tasted like a damp cupboard. Chicken stock benefits from three or four hours because collagen needs time to break down, but even there, an eight-hour simmer mainly adds cost on your energy bill.

A pressure cooker cuts chicken stock to about 45 minutes and uses far less power, which matters when saving money is the point.

Store It So It Actually Gets Used

Stock that sits forgotten in a two-litre tub is not much better than none. Portion it the way you cook.

• Ice cube trays: 30 ml cubes for pan sauces and loosening leftovers.
• 500 ml tubs or bags: the right size for one risotto or a pot of rice.
• Reduced stock: simmer three litres down to one, freeze in cubes, and dilute later to save freezer space.

Lay bags flat to freeze so they stack like books. Stock keeps four days in the fridge and around six months frozen. For thawing and labelling habits, our guide on freezing leftovers without ruining them applies here too.

What the Savings Really Look Like

Say you use 2.5 litres of shop-bought stock a month at around 3 dollars a litre. That is about 90 dollars a year. Homemade stock from scraps costs the energy to simmer it, roughly 30 to 60 cents a batch on a stovetop, less in a pressure cooker. Even counting the occasional bag of cheap wings, most households keep 70 dollars or more a year, and the stock tastes better and contains no added salt.

The bigger saving is less obvious. Once good stock is always in the freezer, cheap ingredients start tasting like a proper meal. Rice cooked in stock instead of water, a pan of lentils, a soup made from the last two potatoes and half an onion: these are dinners that cost under a dollar a portion and do not feel like a sacrifice. That is what keeps people cooking on a budget for years rather than weeks, and it is why I would put a scrap bag ahead of almost any coupon habit.

Questions About Making Stock From Scraps

How long can scraps stay in the freezer bag?

Up to three months is fine. After that, vegetable trimmings can pick up freezer flavours, so aim to make stock whenever the bag is full.

Can I use cooked vegetable leftovers?

Yes, in small amounts, as long as they are plain. Leftovers already cooked with cream, cheese or heavy spice will cloud the stock and make it taste of the old dish.

Why did my stock turn out bitter?

Usually because it simmered too long, boiled hard, or contained brassicas or too many herb stems. Shorten the time and check your bag against the leave-out list.

Start the Bag Tonight

Put an empty bag in your freezer before you cook dinner and add the onion ends and carrot peels you would have thrown away. In ten days you will have enough for your first batch. For more ways to get full value out of every grocery run, see our budget cooking articles.