Asparagus: from farm to canning process

Asparagus may be planted from the seed or as roots. If planted from the seed, 700-1000 days will be required before the first harvest. If planted as roots, a crop may be obtained the first year, depending on the age of the roots. Asparagus is cut when the stalks are about 8 in (20.3 cm) long. Asparagus must be handled quickly as it soon becomes tough and losses its sweetness. Some asparagus is sold as the fresh product, and some is sold as frozen or heat processed.

For freezing, asparagus stalks are cut first at the butt ends, which are discarded, then for length, about 5 in (12.7 cm). The spears and remaining cut portions are then washed (separately), blanched, and cooled. Spears and cut portions are packaged separately and frozen in a plate freezer or blast freezer.

For canning, asparagus spears are handled as above, except that they are cut longer and they are not blanched; otherwise it would be difficult to insert them into container. If glass jars are used, small amount of stannous chloride is added to the brine to prevent fading of the color.

When tin-lined cans are used, the addition of stannous chloride is not necessary, since stannous chloride will be formed during the heat processing. The heat process is aided by the convection heating effect of the brine, provided the containers are kept in the upright position.
Asparagus: from farm to canning process