Effect of package and storage conditions on viability and efficacy of the freeze-dried biocontrol agent Pantoea agglomerans strain CPA-2.
OBJECTIVE
To reduce concentrations of protective and rehydrating media and to evaluate the effect of storage temperature, packaging and atmosphere conditions on the stability of freeze-dried Pantoea agglomerans cells. Efficacy against Penicillium digitatum of freeze-dried cells in orange fruits was also evaluated.


RESULTS
Several concentrations of protective and rehydration media were tested to reduce processing costs. Freeze-dried cells were packed in glass vials or plastic bags under vacuum or nitrogen conditions at 4 and 25 degrees C. After 1 and 3 months, efficacy of freeze-dried P. agglomerans against P. digitatum was tested.


CONCLUSIONS
The results indicate that it is possible to reduce the concentration of non-fat skimmed milk as a rehydration medium from 10% to 1%, maintaining viabilities of 100%. Moreover, freeze-dried cells could be stored in glass vials or in high barrier plastic bags at 4 degrees C for 3 months while maintaining high viabilities and efficacy against P. digitatum.


CONCLUSIONS
The major obstacle in the commercialization of biocontrol products is the development of a shelf-stable formulated product that retains biocontrol activity at a level similar to that of fresh cells. This study suggests that it is possible to maintain viability and efficacy of freeze-dried P. agglomerans cells for at least 3 months.
Costa
E
E
Postharvest Unit, Centre UdL-IRTA, Lleida, Spain. elena.costa@irta.es
Usall
J
J
Teixidó
N
N
Torres
R
R
Viñas
I
I
D001272:Atmosphere; D002957:Citrus / Q000382:microbiology; D005511:Food Handling / Q000379:methods*; D018857:Food Packaging / Q000379:methods; D005612:Freeze Drying; D020636:Pantoea / Q000254:growth & development*; D010407:Penicillium / Q000254:growth & development*; D010572:Pest Control, Biological