Glossary Item

Retorted Products

Retorted products are heated in an unopened, hermetically sealed container for a time, and to a temperature beyond 100°C, sufficient to render the contents commercially sterile. In order to meet the Department of Agriculture, Fisheries and Forestry requirements, all retorted products must not require freezing or refrigeration in order to maintain quality.

Retorting

Retorting refers to the process of cooking canned food or food in a retort pouch after it has been sealed in the container. The packages either go through a continuous retort (i.e. continually moving conveyor system) or may be cooked in a batch retort (i.e. big sealed pressure cooker). Many different types of food may be canned and retorted e.g. canned fruit and vegetables, canned meals (e.g. Irish stew), canned soups, retort pouches of tuna, etc

Hermetically sealed

A package is hermetically sealed if it is 'airtight' e.g. Heat sealed plastic bag, sealed can or glass jar with screw cap. Hermetically sealed goods may also be heat treated but ‘hermetically sealed’ is not the same as ‘canned’ or ‘retorted’. Many foods are packed in hermetically sealed containers, but do not undergo heat treatments in that package. These foods cannot be treated as retorted foods as they may not be sterile. Examples of such foods are milk powders, Milo and some types of cheeses.

Retort Pouches/Packaging

A retort pouch/package is a lightweight, flexible container or pouch in which foods are heated and sterilised. Retort pouches generally have the following features:

1. Manufactured from laminated polyester, nylon and/or aluminium. The polyester and nylon films usually have a layer of aluminium foil between them.
2. Material used for manufacture of retort pouches may be thicker than the polyethylene used for vacuum pouches.
3. Soft and flexible to touch.
4. Do not require special storage conditions to maintain product quality e.g. refrigeration to maintain food quality prior to opening i.e. are shelf stable.

Vacuum Packaging (eg. Corvac or Cryovac)

Vacuum packaging refers to food that is packaged in heat sealed polyethylene bags, from which the air has been removed prior to sealing. ‘Vacuum packaging’ is not the same as ‘retort packaging’. Features of vacuum packaging include:
1. Generally constructed of transparent nylon or polythene in varying thicknesses (no aluminium foil).
2. Soft plastic and wrinkled appearance due to the bag clinging to the product as there is no air inside the bag.
3. Some vacuum packaged foods require special storage conditions to maintain product quality e.g. vacuum packaged meat or fish require refrigeration, i.e. are not shelf stable.
4. Some vacuum packaged foods do not require special storage conditions to maintain product quality e.g. ground coffee, nuts.

Shelf Stable

Shelf stable refers to food that will last for an extended period of time, packaged or not, without any special storage conditions. For example heat-treated canned/retorted food will last many years on the shelf.