ABSTRACT
Mechanical agitation of cans in rotary retorts enhances heat transfer rates to liquid particle mixtures that might otherwise heat at much slower rates (conduction to mild convection). Agitation processing not only has the potential to improve quality retention, but also to reduce energy consumption during processing. Semisolid and viscous foods such as sauces and soups containing meat or vegetables are mostly
processed in rotational retorts. Thermal sterilization of such products requires that the center of the target particle receive a predetermined minimum heat process. Heat transfer in such systems has been analyzed using heat penetration parameters (heating rate index, f
, and heating lag factor, j
) and convective heat transfer coefficients (overall heat transfer coefficient, U, and fluid-to-particle heat transfer coefficient, h
). Early studies focused only on convective heat transfer rates to canned liquids
(Berry et al., 1979; Berry and Bradshaw, 1980, 1982; Berry and Dickerson, 1981). These were product-specific studies on the influence of agitation on heat transfer rates.
