Rank the following steps in the retort canning process in the correct order.
- Process the containers until the cold spot reaches the target time and temperature, usually at least 121 degrees celsius for 3 min.
- The containers should be sealed after the food products are filled.
- Place these containers into a pressure-resistant container.
- Heat up the containers under pressure, usually up to 30 psi
- Fill the containers that are going to be used with food products
