How to Dry Age Beef at Home in a Membrane Bag

Pick a whole, boneless or bone-in piece of 2–8kg: scotch fillet, sirloin, striploin, rump or a bone-in rib. Look for good marbling and an outer fat cap, which protects the muscle while it ages.

Buy it fresh from your butcher and make sure it hasn't already been wet-aged in a vacuum bag or stored long in a cool room. Avoid single steaks: after trimming the crust there would be little left.

Wash your hands, board and knife before you start. Don't wash the meat or pat it dry: the natural surface is part of the aging process, and every extra touch is a chance for contamination.

Using the roll? Cut a piece long enough for the cut plus about 8cm, and seal one end first.

Fold the open edge of the bag outward like a cuff, slide the meat in, then fold the edge back. The seal area must stay completely free of juice and fat, or the seal won't hold. Leave about 8cm of free film at the open end.

A-Vac membrane behaves differently from every other vacuum bag. It is thinner and welds at lower heat, so the setting you use for normal bags will usually burn through it.

Before you seal the bag with the meat in it, make a few test seals on an offcut or on the free end of the bag. On a LAVA sealer, start at level 1–2. A good seal is a clean, continuous line that doesn't tear when you pull the film apart.

The membrane is smooth on both sides, like a chamber vacuum bag. An external vacuum sealer needs embossed channels to draw the air out, so on its own it can't evacuate a smooth bag.

The Vac-Aid strip solves this. It works like a straw between the bag and the sealer: put one end into the bag, and let the other end reach into the vacuum area of the machine. The air then travels out along the strip.

Start the vacuum. It takes noticeably longer than with normal bags, even on a LAVA, because all the air has to leave through the strip.

Help it along: massage the air pockets with your hands towards the strip. Keep going until the film sits tight on the whole surface of the meat with no air pockets left.

Seal the bag while the strip is still in place. Then trim the overhanging part of the Vac-Aid strip right at the seam.

Now seal a second time, just above the first seam. The first seal runs across the strip and can open over the weeks; the second one closes the bag reliably for the whole aging time.

Put the bag on a wire rack in the coldest part of the fridge, at 1–3 °C. Air must reach it from all sides, so don't let it touch the walls or other food, and never put anything on top of it.

In the first 3–5 days the membrane bonds with the meat surface. Don't move the bag during this time. Then simply wait: at least 21 days for beef, and around 28 days for a deeper, nutty flavour. Lamb is ready after 2–3 weeks.

Peel off the bag. The meat will be darker, with a firm, dry crust, and should smell pleasant and nutty, never sour.

Shave off the dark crust with a sharp knife until you reach the deep red meat. Don't throw the trim away: it makes an excellent stock.

Cut the aged piece into steaks and cook them hot on the grill or in a pan. Dry-aged beef needs little more than salt.

For steaks you won't cook straight away, vacuum pack them in heavy-duty DRY AGER bags and freeze them. They keep their flavour and look like a butcher's pack.