Canned foods are divided in low acid and high acid categories. Low acid are considered those with pH value greater than 3.5, while high acid are those with a pH value equal or smaller than 3.5.
Acid foods are less likely to develop high temperature resistant microorganisms and a treatment at temperatures in the range of 70-90ºC is sufﬁcient to prevent fermentation during the storage time. Some low acid foods with pH values below 4 can be preserved without sterilization by addition of acids (acidiﬁed foods).
The batch retorts and pressure sterilizers are used for sterilization processes as well as for pasteurization processes, as long as the internal pressure built up inside the pack exceeds the atmospheric pressure, as a result of thermal expansion of the foods or internal gas. The pressure built in the retort/sterilizer due to the supply of steam and/or compressed air overpressure will compensate the internal pressure built in the pack so as to prevent seal damage or package deformation.
Surdry has installed solutions for all the following list of products and is offering constant innovation for many upcoming developments.