Bacterial injury and repair related to nonthermal and thermal processes
D. G. HOOVER, Dept. of Animal & Food Sciences, Univ. of Delaware, 017 Townsend Hall, Newark, DE 19717
My presentation will overview the body of information dealing with injury and recovery of bacteria exposed to food processing methods and other environmental stresses. Attempts will be made to distinguish nonthermal methods from conventional thermal processing in addition to those approaches that combine nonthermal procedures with mild elevated temperatures and other elements of food technology. General phenomena and mechanisms in bacteriology regarding cellular stress and stress recovery will be reviewed starting with heat response (degree of inactivation in populations, damage to the membrane, enzymes and ribosomes, and synthesis of heat-shock proteins) with progression to other environmental stresses including nonthermal methods such as use of low temperatures, chemical preservatives, hydrostatic pressure, irradiation, electricity, sonication, and other forms of energy. Attention will be paid towards foodborne pathogens and alteration of virulence properties due to stress. In addition, injury to bacterial endospores and the concern of VBNC (viable but nonculturable) in gram-negative bacteria will be covered.
Session 6, Effect of combinations of thermal and nonthermal treatments on microbial survival