The Half-Used Tin Is the Most Likely Thing in Your Kitchen to Be Thrown Away

Two tablespoons of tomato paste from a tin of six. Half a can of coconut milk. Four anchovies out of a jar of twenty. Most of a tub of buttermilk bought for one batch of pancakes.

Nobody decides to waste these. The recipe asks for a fraction, the packaging comes in one size, the remainder goes into the refrigerator without a plan, and it is discovered three weeks later in a state that makes the decision for you.

It is the most predictable form of food waste in a household and it has one general solution and about a dozen specific ones.

The general solution is to portion it on the day it is opened

Not later, when there is a plan. The plan is what never arrives.

Almost everything on the list below freezes in small portions, and a frozen portion has no deadline. An ice cube tray, a flat bag and eight seconds of tape solve the whole category, and a labeled portion is worth something while an unlabeled one is not.

The dozen things it actually happens to

Tomato paste. Spoon the remainder in tablespoon blobs onto a tray, freeze, bag them. Each blob is one recipe’s worth, used from frozen. Or buy it in a tube, which keeps for weeks in the refrigerator and is the better purchase for most households. Either way, fry it until it darkens, because that is where its value is.

Coconut milk. Freezes well for cooking. It separates on thawing and comes back together with heat and stirring, which is fine in a curry and wrong in a dessert that needed it smooth.

Anchovies. Cover the remainder completely in oil and they keep for weeks refrigerated; frozen, indefinitely. They are also the least visible way to add depth to almost any savory dish, because savory intensity multiplies rather than adds and one fillet melted into a pan disappears entirely.

Chipotles in adobo. Blend the entire tin, contents and sauce, into a paste. Freeze it flat in a bag and snap off what you need. A tin lasts a year this way and rots in a fortnight in its own can.

Buttermilk. Freezes. Or use it as a marinade, or in anything that wants acid you can spoon, or in a soda-leavened batter where its acid is what makes the soda work.

Cream. Freezes acceptably for cooking and never whips afterward, because the fat structure is damaged. Fat percentage decides what dairy can survive, and freezing is one more thing high-fat cream tolerates and milk does not.

Tahini, miso, gochujang, harissa. All of these keep for months refrigerated and are far more robust than people assume. Miso is effectively indefinite. Stir tahini before the oil separates rather than after, and it becomes a dressing base rather than a solid brick.

Canned beans. Freeze them in their own liquid rather than drained, which protects the texture. The liquid itself is an ingredient and thickens a soup.

Stock from a carton. Flat bags, immediately. An opened carton has days; a frozen bag has months.

Wine. Half a bottle is an ingredient rather than a failure of planning, and frozen in cubes it is the exact amount a pan sauce wants.

Herbs. Chopped and packed into a tray with oil, where the fat holds the volatile compounds that air would take. The tender ones are the ones that need this; the hardy ones dry.

Chiles, ginger and lemongrass. All better frozen whole than stored fresh, and all grate from frozen.

Get it out of the tin the moment it is open

An opened can is metal in contact with acidic food and air, and the contents pick up a faint metallic taste within a day.

Decant into glass, cover it, and write the date on it. That is thirty seconds and it is the difference between an ingredient and an archaeological find. The date you write is more informative than the one printed on the tin, because it is the only one that knows when air got in.

Some of it is a buying decision rather than a storage one

Tomato paste in a tube instead of a tin. The small tin of coconut milk instead of the large one. Anchovies in a jar with a lid instead of a flat tin. A half bottle of vermouth rather than a full one.

Each of those costs marginally more per ounce and considerably less per use, which is the same arithmetic as buying small bottles of anything that goes flat. Spending on what does not spoil is the general version, and this is the specific one: the cheapest version of an ingredient you throw half of away is not cheap.

And one shelf

Put everything currently open on one shelf at eye level, and cook from that shelf before opening anything new.

It is not a system and it requires no containers. It works because the entire problem is that half-used things become invisible, and the only thing standing between most of them and the bin is somebody remembering they exist.

Part of Kitchen Systems.