Commercially available dry lager yeast strain and three LAB strains
were used in the experiment. LAB strains
have been previously evaluated and showed individual percentages
of AFM1 removal in UHT milk at 37 C ranging from 24.5 to 33.5%.
The lyophilized yeasts were reactivated in sterile water and
cultivated at 23 C, according to recommendations of Fermentis Ltd.
The number of yeast cells in the suspensionwas determined by light
microscopy using a modified Neubauer chamber. The suspension
was diluted with sterile water until reaching a cell concentration of
1.0 109 cells mL1.
Individual LAB lyophilized strains were reactivated in MRS broth and
incubated at 37 C until reaching at least 1.0 109 colony forming
units (CFU) mL1, as determined by serial dilution and pour plate
counting after incubation at 37 C for 24 h
under anaerobic condition. Convenient volumes of each cultured
broth were mixed to achieve a pool of the three LAB strains containing
a total cell concentration of 1.0 1010 cells mL1. All S.
cerevisiae and LAB cells were heat-killed, being inactivated by
boiling at 100 C for 1 h before the binding assays, to avoid any
possible milk fermentation during the contact time.