Incubation time and water activity effects on ochratoxin A production by Aspergillus section Nigri strains isolated from grapes.
OBJECTIVE
The objective of this study was to determine the temporal ochratoxin A (OTA) accumulation profile of Aspergillus section Nigri at different water activity (aw) levels.


RESULTS
Two Aspergillus carbonarius and two Aspergillus niger aggregate strains isolated from grapes were tested in vitro for OTA accumulation at 25 degrees C on synthetic nutrient medium, over periods of 20 days at different aw levels. Results were modelled by a multiple linear regression and response surface predictive models were obtained. High levels of aw favoured OTA production by these moulds. Maximum amounts of OTA were found at the earlier growth states (5 days for A. carbonarius and 7-13 days for A. niger aggregate).


CONCLUSIONS
Provided that A. section Nigri, and mainly A. carbonarius, play the main role in OTA presence in grapes, it would be critical to adjust the harvest and processing time to significantly reduce the chances for OTA accumulation.


CONCLUSIONS
Ochratoxin A production by A. section Nigri has been shown for the first time to occur optimally after as little as 5 days on a grape-like medium.
Bellí
N
N
Food Technology Department, CeRTA-UTPV, University of Lleida, Lleida, Spain.
Ramos
A J
AJ
Sanchis
V
V
Marín
S
S
D001234:Aspergillus niger / Q000201:enzymology* / Q000302:isolation & purification; D003470:Culture Media / Q000737:chemistry; D009793:Ochratoxins / Q000032:analysis / Q000096:biosynthesis* / Q000302:isolation & purification; D013997:Time Factors; D027843:Vitis / Q000382:microbiology*; D014867:Water / Q000737:chemistry
D003470:Culture Media; D009793:Ochratoxins; D014867:Water; C025589:ochratoxin A