contain violet red bile (VRB) nutrients, gelling agent and an indicator
of glucuronidase activity. As in Section 2.4, 1 mL of juice
samples was used to inoculate the Petri Films and incubated for
24 h at 35 C and the red colonies with formed gas were counted.
Coliforms are considered gramnegative rods which ferment lactose
and produce acid and gas. The produced acid changes the pH
modifying the gel color into darker red. The gas trapped around red
colonies confirms the presence of coliforms.
2.6. Yeasts and molds
All of the juice samples were analyzed in triplicates for yeasts
and molds following the AOAC 997.02 method (AOAC., 2005) using
Petri Films (3M Microbiology, St Paul, MN, USA). The Petri Films
contain nutrients and a gelling agent favorable for yeast and molds
growth. Yeast are typically indicated by small blue-green colonies
with diffuse edges and center foci while molds are identified by
large variably colored colonies with diffuse edges and center foci.
One mL of juice was used as the inoculant as explained previously.
Yeasts and molds colonies were counted after an incubation period
of 3e5 days at room temperature.
The APC, TC and yeasts and molds colonies were counted and
reported as Log CFU/mL; and the CFU/mL were determined from Eq.
(2).