The ability of the osmotolerant yeast Debaryomyces hansenii to inhibit Penicillium nordicum, the most common
ochratoxigenic mould encountered in dry-cured meat products, was evaluated. The antagonistic effect of ten
D. hansenii strains isolated from dry-cured ham was screened in vitro using malt extractmedia andmeat extract
peptone media with thewater activity (aw) adjusted to 0.97 and 0.90. A significant inhibition of the two tested P.
nordicum strains by D. hansenii cells and cell-free supernatants was observed. At 0.97 aw, increasing D. hansenii
inoculum concentrations significantly improved the inhibition of mould growth on solid medium, whereas at
0.90 aw this was not always the case. As observed by bright field microscopy, most D. hansenii strains were
able to delay P. nordicum spore germination when co-cultured in malt extract broth. D. hansenii FHSCC 253H
showed the highest overall in vitro inhibition of ochratoxigenic mould growth, and was therefore chosen for
co-cultivation assays in dry-cured ham slices incubated at 0.94 and 0.84 aw simulating ham ripening. Regardless
of the experimental conditions tested, lower levels of the inoculated P. nordicum strain were detected in cocultivation
batches compared with batches without D. hansenii. The highest level of mould growth inhibition
was observed in batches at 0.94 aw. Ochratoxin A (OTA) production in ham samples was detected by HPLCMS.
Co-culturing of P. nordicumwith D. hansenii FHSCC 253H resulted in lower OTA levels comparedwith control
samples without D. hansenii. The decrease of the mycotoxin presence due to D. hansenii FHSCC 253H was more
efficient at 0.94 aw (OTA was below the detection limit). In conclusion, D. hansenii is potentially suitable as a
biopreservative agent for preventing ochratoxigenic mould growth and OTA accumulation in dry-cured meat
products. The inoculation of D. hansenii should be made at the beginning of processing (at the end of post salting)
when the aw of the product is still high (near 0.94). This action in addition to application of appropriate hygienic
actions and control of temperature and relative humidity throughout ripening is required to reduce health risks
due to OTA exposure.
The ability of the osmotolerant yeast Debaryomyces hansenii to inhibit Penicillium nordicum, the most commonochratoxigenic mould encountered in dry-cured meat products, was evaluated. The antagonistic effect of tenD. hansenii strains isolated from dry-cured ham was screened in vitro using malt extractmedia andmeat extractpeptone media with thewater activity (aw) adjusted to 0.97 and 0.90. A significant inhibition of the two tested P.nordicum strains by D. hansenii cells and cell-free supernatants was observed. At 0.97 aw, increasing D. hanseniiinoculum concentrations significantly improved the inhibition of mould growth on solid medium, whereas at0.90 aw this was not always the case. As observed by bright field microscopy, most D. hansenii strains wereable to delay P. nordicum spore germination when co-cultured in malt extract broth. D. hansenii FHSCC 253Hshowed the highest overall in vitro inhibition of ochratoxigenic mould growth, and was therefore chosen forco-cultivation assays in dry-cured ham slices incubated at 0.94 and 0.84 aw simulating ham ripening. Regardlessof the experimental conditions tested, lower levels of the inoculated P. nordicum strain were detected in cocultivationbatches compared with batches without D. hansenii. The highest level of mould growth inhibitionwas observed in batches at 0.94 aw. Ochratoxin A (OTA) production in ham samples was detected by HPLCMS.Co-culturing of P. nordicumwith D. hansenii FHSCC 253H resulted in lower OTA levels comparedwith controlsamples without D. hansenii. The decrease of the mycotoxin presence due to D. hansenii FHSCC 253H was moreefficient at 0.94 aw (OTA was below the detection limit). In conclusion, D. hansenii is potentially suitable as abiopreservative agent for preventing ochratoxigenic mould growth and OTA accumulation in dry-cured meatproducts. The inoculation of D. hansenii should be made at the beginning of processing (at the end of post salting)when the aw of the product is still high (near 0.94). This action in addition to application of appropriate hygienicactions and control of temperature and relative humidity throughout ripening is required to reduce health risksdue to OTA exposure.
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