Listeria monocytogenes: The Hidden Threat in Low-Moisture Foods

News 26 11 月, 2024

Introduction

As awareness of food safety increases, the food industry is actively seeking methods to control foodborne pathogens. A recent review published in Trends in Food Science & Technology highlights the survival characteristics of Listeria monocytogenes in low-moisture foods and how this impacts the effectiveness of thermal processing in food production.

A Pathogen with Exceptional Adaptability

Listeria monocytogenes is a Gram-positive bacterium capable of causing severe foodborne illnesses, such as meningitis and septicemia. It thrives in cold environments, posing risks to refrigerated products. Uniquely, it can survive in low-moisture conditions, making even dry foods a potential habitat.

Challenges in Low-Moisture Foods

Foods like baked goods, nuts, dried fruits, and spices were long considered safe due to their low moisture content. However, recent food safety incidents have revealed that even these products can harbor Listeria monocytogenes.

Survival Strategies in Dry Environments

This bacterium can persist in dry conditions for months or years, entering a dormant state that helps it withstand desiccation. Low moisture levels also increase its resistance to heat, reducing the effectiveness of traditional thermal processing.

Factors Influencing Heat Resistance

The thermal stability of Listeria monocytogenes in low-moisture foods depends on factors like food composition, storage temperature, and pH. For instance, proteins and carbohydrates may create a protective barrier, shielding the bacteria from heat. Lower storage temperatures further enhance its heat resistance.

Control Strategies

To address this challenge, researchers suggest:

• Enhanced Heat Treatments: Use higher temperatures or prolonged heating times to overcome bacterial resistance.
• Non-Thermal Technologies: Methods like high-pressure processing and irradiation can reduce pathogens without compromising food quality.
• Antimicrobial Additives: Employ natural or chemical preservatives to inhibit bacterial growth.

Conclusion

The resilience of Listeria monocytogenes in low-moisture foods demands robust control strategies. By combining advanced processing techniques with stringent hygiene monitoring, food manufacturers can mitigate risks and protect consumer health. Ongoing research will continue to explore innovative solutions for ensuring the safety of low-moisture foods.

Reference
H. M T, Mei-Jun Z. Control of Listeria monocytogenes in low-moisture foods [J]. Trends in Food Science & Technology, 2021, 116:802-814.