Canned Foods: Principles of Thermal Processing

Abstract

The history of food industry is strictly correlated with a peculiar category of long-durability edible products: canned foods. Differently from other packaged foods, canned foods show several unique properties, including risks and failures, depending on the composition of edible contents, the production of metal packages and preservation techniques. Thermal processes have the basic aim of destroying microorganisms (bacteria and spore-forming life forms) in foods. The inhibition of microbial growth and the inactivation of microbial toxins are also needed. Other factors—pH, presence of fatty molecules, calcium, etc—are important. As a result, the choice of the ‘right’ thermal treatment (pasteurisation, sterilisation) and related process parameters (time, temperature) have to be considered in different ambits, including canned foods (Chen in J Food: Microbiol Saf Hyg 02(1), 2017; Chen et al. in J Sci Food Agric 93(5):981–986, 2013; Gupta and Balasubramaniam in Novel thermal and non-thermal technologies for fluid foods. Academic Press, London, Waltham, and San Diego, pp. 109–133, 2012; IciEr in Novel thermal and non-thermal technologies for fluid foods. Academic Press, London, Waltham, and San Diego, pp. 305–367, 2012; Jongyingcharoen and Ahmad in Functional foods and dietary supplements: processing effects and health benefits. Wiley, Chichester, UK, 2014; Manas and Pagan in J Appl Microbiol 98(6):1387–1399, 2005; Rastogi in Novel thermal and non-thermal technologies for fluid foods. Academic Press, London, Waltham, and San Diego, pp. 411–432, 2012; Sahin and Sumnu in Physical properties of foods, pp. 107–155, 2006; Tiwari and Mason in Novel Thermal and non-thermal technologies for fluid foods. Academic Press, London, Waltham, and San Diego, pp. 135–165, 2012; Vasseur et al. in J Appl Microbiol 86(3):469–476, 1999). Final results are the construction of logarithmic ‘survival curves’, the definition of factors which can reduce thermal destruction of microorganisms (water activity and pH). In addition, some reflection should be made when speaking of ‘commercial sterility’ and the correlated concept of long durability for canned foods (storage at room temperature).