Modelling the effect of temperature, water activity and carbon dioxide on the growth of Aspergillus niger and Alternaria alternata isolated from fresh date fruit.
OBJECTIVE
To quantify and model the combined effects of temperature (T) (10-40°C), water activity (aw) (0·993-0·818) and CO2concentration (9·4-55·1%, v/v) on the growth rate of Aspergillus niger and Alternaria alternata that cause spoilage during the storage and packaging of dates.


RESULTS
The effects of environmental factors were studied using the γ-concept. Cardinal models were used to quantify the effect of studied environmental factors on the growth rates. Firstly, the cardinal parameters were estimated independently from experiments carried out on potato dextrose agar using a monofactorial design. Secondly, model performance evaluation was conducted on pasteurized date paste. The boundary between growth and no-growth was predicted using a deterministic approach. Aspergillus niger displayed a faster growth rate and higher tolerance to low awthan Al. alternata, which in turn proved more resistant to CO2concentration. Minimal cardinal parameters of T and awwere lower than those reported in the literature.


CONCLUSIONS
The combination of the awand CO2effects significantly affected As. niger and Al. alternata growth. The γ-concept model overestimated growth rates, however, it is optimistic and provides somewhat conservative predictions.


CONCLUSIONS
The developed model provides a decision support tool for the choice of the date fruit conservation mode (refrigeration, drying, modified atmospheric packaging or their combination) using T, awand CO2as environmental factors.
Laboratoire de Biomathématique, Biophysique, Biochimie, et Scientométrie, Faculté des Sciences de la Nature et de la Vie, Université de Bejaia, Bejaia, Algérie.
A
A
Belbahi
Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, Université de Brest, Quimper, France.
I
I
Leguerinel
Food Process Engineering Research Unit, CIRAD, UMR QualiSud, Montpellier, France.
J-M
JM
Méot
Food Process Engineering Research Unit, Montpellier SupAgro UMR QualiSud, Montpellier, France.
G
G
Loiseau
Laboratoire de Biomathématique, Biophysique, Biochimie, et Scientométrie, Faculté des Sciences de la Nature et de la Vie, Université de Bejaia, Bejaia, Algérie.
K
K
Madani
Food Process Engineering Research Unit, Montpellier SupAgro UMR QualiSud, Montpellier, France.
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P
Bohuon
D000528:Alternaria / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D001234:Aspergillus niger / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D002245:Carbon Dioxide / Q000494:pharmacology; D005638:Fruit / Q000382:microbiology; D008954:Models, Biological; D065749:Phoeniceae / Q000382:microbiology*; D013696:Temperature; D014867:Water
D014867:Water; D002245:Carbon Dioxide
date fruit; environmental factors; fungal growth; growth/no-growth boundary; modelling