Recent developments in low-moisture foods: microbial validation studies of thermal pasteurization processes

Abstract

Outbreaks associated with low-moisture foods (e.g., wheat flour, nuts, and cereals) have urged the development of novel technologies and re-validation of legacy pasteurization process. For various thermal pasteurization processes, they share same scientific facts (e.g., bacterial heat resistance increased at reduced water activity) and guidelines. However, they also face specific challenges because of their different heat transfer mechanisms, processing conditions, or associated low-moisture foods’ formulations. In this article, we first introduced the general structural for validating a thermal process and the shared basic information that would support our understanding of the key elements of each thermal process. Then, we reviewed the current progress of validation studies of 7 individual heating technologies (drying roasting, radiofrequency-assisted pasteurization, superheated steam, etc.) and the combined treatments (e.g., infrared and hot air). Last, we discussed knowledge gaps that require more scientific data in the future studies. We aimed to provide a process-centric view point of thermal pasteurization studies of low-moisture foods. The information could provide detailed protocol for process developers, operators, and managers to enhance low-moisture foods safety.

Keywords:

• Thermal pasteurization
• Salmonella
• Enterococcus faecium
• heating technology
• lethality

Acknowledgments

The authors thank National Natural Science Foundation of China (31901793) for financial support and the China Scholarship Council for supporting Shuxiang Liu’s Ph.D. study.

Author contributions

Shuxiang Liu compiled data from literature review and drafted the manuscript. Xinyao Wei revised the manuscript and contributed to section 2 and 3. Professor Juming Tang revised the manuscript and contributed to the section 3. Professor Wen Qin revised the manuscript and contributed to the section 4. Professor Qingping Wu supervised the work, revised the manuscript, and contributed to section 2. All authors reviewed the manuscript before submission.

Conflicts of interest

The authors declare that there are no conflicts of interest.