I want to open a small cannery in my town.Aim is to provide canning services to the local community.People would bring their fully cooked meals( mostly gravies) to get them canned.
The questions are
Wheather the exahsting process is compulsory before sealing and retorting the cans?
Can I CAN rice and potatoes?
Would appreciate some guidance from you folks
126.96.36.199.Exhausting of filled cans
The importance of removal of air from the cans after filling the food was realized by canning experts from the very beginning. Even in historical days of canning, it was thought that the contact of air with food was responsible for the spoilage and if the air was removed, food could be preserved for long time after heat processing.
Even the famous chemist Gay Lusac thought in the same way. However, if air is not removed from the can while sealing, it would expand during heat processing and can ends (lids) become permanently convex and it would be rejected thinking that the food inside was spoilt. Also, due to high pressure inside the can, seam would get loosened and entry of air and bacteria may take place and spoil the product. Hence, it is essential to exhaust the can prior to sealing.
(v) Exhausting and sealing: Exhaustion or removal of air from the can before it is sealed, is necessary for the following reasons: 1-) To prevent expansion of the contents during processing which may force the seam. 2-) To produce concave can ends so that any internal pressure may be readily detected and the can rejected. 3-) To lower the amount of oxygen in the can and prevent discolouration of the food surface. 4-)To reduce chemical action between the food and container and hydrogen swells. 5-)To prevent internal corrosion of the cans.
EXHAUSTING OF CONTAINERS
The exhausting of containers of lacf must be controlled so as to meet the conditions for which the process was designed. Exhausting of containers is designed to remove the air from the container and to provide a vacuum in the container. Air remaining in the headspace of the container contains oxygen which may interact with the product and the container increasing the rate of deterioration. Vacuum is measured in terms of inches of mercury (Hg.). 30 in. Hg. indicates a complete vacuum, 0 in. Hg. indicates a lack of vacuum, and 10 in. Hg. indicates that 1/3 of the air has been removed from the headspace of the container. In the United States some foods may be packed with vacuums as low as two to six in. Hg. The normal range is from 10 to 20 in. Hg. Some foods may be packed with higher vacuums of up to 26 in. Hg. In Europe very low to no vacuums are sometimes used to pack products such as small fish which are filled at room temperature into small low profile containers. The lack of a vacuum in these containers may at times place the lot under suspicion when containers appear to be abnormal.