Pasteurization of milk and the heat resistance of Mycobacterium avium subsp. paratuberculosis: a critical review of the data.

Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) causes Johne's disease in ruminants (including cattle, sheep and goats) and other animals, and may contribute to Crohn's disease in humans. This possibility, and the fact that M. paratuberculosis may be present in raw milk, make it important to ensure that the heat treatment specified for pasteurization of milk will give acceptable inactivation of this bacterium, with an adequate margin of safety. Published studies of the heat resistance of this bacterium in milk have given widely differing results. Possible reasons for these differences, and the technical problems involved in the work, are reviewed. It is concluded that there is a need (i) for the adoption of an agreed Performance Criterion for pasteurization of milk in relation to this bacterium, (ii) a need for definitive laboratory experiments to understand and determine the heat resistance of M. paratuberculosis, and (iii) a need for an assessment of whether the minimum heat treatments specified at present for pasteurization of milk (Process Criteria) will meet the Performance Criterion for M. paratuberculosis. Measures are also required to ensure that commercial processes deliver continually the specified heat treatment, and to ensure that post-pasteurization contamination is avoided.

Industry Perspectives on the Use of Natural Antimicrobials and Inhibitors for Food Applications.

The wide range of extremely effective naturally occurring antimicrobial systems include those derived front animals (e.g., enzymes such as lysozyme and lactoperoxidase; other proteins such as lactoferrin, lactoferricin, ovotransferrin, and serum transferrins; small peptides such as histatins and magainins; and the immune system), those derived front plants (e.g., phytoalexins, low- molecular-weight components of herbs and spices; phenolics such as oleuropein; and essential oils) and those derived front microorganisms (e.g., bacteriocins such as nisin and pediocin). An increasing number of such natural systems is being deliberately utilized for food preservation, or being explored for such use. The future potential is substantial, particularly as the efficacy of these systems is demonstrated in additive or synergistic combinations with some of the other antimicrobial factors that we can employ to improve the safety and shelf stability of foods. While "naturalness" alone is not necessarily a sufficient objective for these developments, the use of natural inhibitors as components of systems that can together enhance the effectiveness of preservation, with advantages in product quality and safety, justifies pursuit.