Articles
TEMPERATURE VARIABILITY AND PREDICTION OF FOOD SPOILAGE DURING URBAN DELIVERY OF FOOD PRODUCTS
Article number
674_6
Pages
63 – 69
Language
English
Abstract
Urban refrigerated transport used for home deliveries is characterized by the use of small vans with frequent, though short-lived, temperature variations.
The present paper investigated the temperature variability in the chiller compartment of a multi-temperature van.
Integration of the measured temperature histories with mathematical models to predict growth of pseudomonads and Escherichia coli, showed that products presented adequate growth temperatures for pseudomonads, but less than half the temperatures measured were suitable for E. coli growth.
The thermal behaviour of the food products inside the van was strongly influenced by the loading period.
Three theoretical scenarios were additionally tested: (A) transport followed by domestic storage at 5°C during 24-hr; (B) transport followed by domestic storage at 10°C during 24-hr and (C) both transport and domestic storage fulfilling a no-more-than-5°C guideline.
Scenario B led to a predicted nine-fold and a 2,000-fold increase in the growth of E. coli and pseudomonads, respectively, after the domestic refrigeration stage.
The predicted growth of pseudomonads for Scenarios A and C were similar, even though Scenario A presented temperature excursions above the 5°C limit.
These results highlight the multifactorial nature of food quality and the need to broaden the scope of current regulations into more sophisticated quality control approaches.
One possibility is the use of time-temperature indicators coupled with models that describe the dynamic behaviour of spoilage and pathogenic bacteria.
The present paper investigated the temperature variability in the chiller compartment of a multi-temperature van.
Integration of the measured temperature histories with mathematical models to predict growth of pseudomonads and Escherichia coli, showed that products presented adequate growth temperatures for pseudomonads, but less than half the temperatures measured were suitable for E. coli growth.
The thermal behaviour of the food products inside the van was strongly influenced by the loading period.
Three theoretical scenarios were additionally tested: (A) transport followed by domestic storage at 5°C during 24-hr; (B) transport followed by domestic storage at 10°C during 24-hr and (C) both transport and domestic storage fulfilling a no-more-than-5°C guideline.
Scenario B led to a predicted nine-fold and a 2,000-fold increase in the growth of E. coli and pseudomonads, respectively, after the domestic refrigeration stage.
The predicted growth of pseudomonads for Scenarios A and C were similar, even though Scenario A presented temperature excursions above the 5°C limit.
These results highlight the multifactorial nature of food quality and the need to broaden the scope of current regulations into more sophisticated quality control approaches.
One possibility is the use of time-temperature indicators coupled with models that describe the dynamic behaviour of spoilage and pathogenic bacteria.
Authors
S. Estrada-Flores, D. Tanner
Keywords
temperature, spoilage, transport, pseudomonads, E. coli, food
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