Heat resistance of Listeria monocytogenes in vegetables : Evaluation of blanching processes

• Published in: Journal of food protection Vol. 64; no. 3; pp. 385 - 387
• Main Author: MAZZOTTA, Alejandro S
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association of Milk, Food and Environmental Sanitarians 01.03.2001
• Subjects: Biological and medical sciences; Food Handling - methods; Food industries; Food microbiology; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Hot Temperature; Listeria monocytogenes - physiology; Time Factors; Vegetables - microbiology; Heat treatment; Microbiological testing; Thermal resistance; Pathogenic; Listeria monocytogenes; Bacteria; Biological contamination; Vegetable; Blanching
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-64.3.385

The heat resistance of a Listeria monocytogenes composite (serotypes 1/2a, 1/2b, and 4b) was determined in fresh broccoli florets, sweet green peppers, onions, mushrooms, and peas using an end-point procedure in polyester pouches. The heat resistance of L. monocytogenes was higher in peas (D(60 degrees C) = 1.0 min) and mushrooms (D(60 degrees C) = 0.7 min) than in other vegetables tested (D(60 degrees C) in onions = 0.2 min) and was highest when cells were subjected to starvation before the thermal death time experiments (D(60 degrees C) of starved L. monocytogenes in mushrooms = 1.6 min). The results showed that blanching can be used as an antilisterial treatment (inactivation of 5 logs of L. monocytogenes) when the cold spot of vegetables is treated for at least 10 s at 75 degrees C or instantaneously (<1 s) at temperatures above 82 degrees C.