A pork loin joint is the sliceable roast: a neat eye of meat, a fat cap, and no shoulder collagen to hide behind. It wants a timed oven and a rest, not a four-hour pull. Pork Loin Joint 1kg is a small table. Boneless Pork Loin Joint 3kg is a crowd and a week of cold cuts. Both live in pork loin and pork joints.
1kg loin in the oven
Score the fat, salt it, and sit it on a rack or on onions. 180°C for about 1 hour 10 minutes on a 1kg joint, 30 minutes per 500g plus 20 minutes as a starting rule, but a probe to 70°C in the centre is the truth. Rest 15 minutes. If you want the fat crisper, 20 minutes at 220°C at the start, then drop to 180°C to finish. Loin dries past 75°C; pull it at 70°C and let the rest take it a little higher. That is how you get slices that are moist rather than school-dinner white.
The 3kg joint
The 3kg boneless loin is a different piece of kit: same temperature, longer time, about 2 hours 30 minutes to 3 hours, still to 70°C. Tent with foil if the fat is dark before the centre is ready. Rest 20 to 25 minutes. It carves like a ham and cold-cuts for days, which is the real reason to buy 3kg rather than three 1kg joints that each overcook while you wait. Shop large roasting joints and Sunday roast if the same table wants beef or lamb as well.
Air fryer, stuffing and mistakes
A 1kg loin often fits an air fryer: 180°C for 50 to 60 minutes, turning once, probe, rest. Stuffing belongs under the joint or in a separate dish; pushing a wet stuffing into a small loin is how the centre stays under while the outside dries. Do not confuse this with Belly Pork Joint 1kg, which is a crackling roast with more fat, or with shoulder, which you pull. Loin is for slices and sandwiches. Gravy from the tin, apple sauce, mustard. Leftovers are better than the hot dinner if you roasted it right.
A 1kg loin is four plates with roast potatoes. A 3kg loin is a party and then a week of sandwiches, which is the better buy if you will actually eat the cold meat. If leftover roast pork sits in your fridge until it is a science project, buy the 1kg. Match the joint to the household, not to the photograph.
Probe 70°C, rest, carve across. That is a pork loin joint, whether you bought 1kg or 3kg.