This article is from the Food Preserving FAQ, by Eric Decker email@example.com with numerous contributions by others.
Product sampling was done by aseptically removing 25 g of unbaked or
baked bread samples and diluting in 225 ml sterile phosphate buffer in
a stomacher bag with filter. The sample was stomached for 2 min using
a Stomacher 400Th1 (Tekmar). The suspension was serially diluted and 1
ml of each dilution was used for microbial analyses(1,2).
Eight samples were collected before baking and analyzed for their
microbial quality. Eight samples were also collected from each baking
treatment for microbial analysis. The experiment was replicated twice
and all samples were analyzed in duplicates. Samples were either
uninoculated or inoculated with spores at a level of I0~ CFU/g and were
tested for total aerobic plate count (APC) and C. sporo genes PA 3679
count before and after heat treatment at 177 C (350 F), 191 C (375 F)
and 204 C (400 F). After baking, jars were allowed to cool at room
temperature for several hours (about 8 h) before sampling and microbial
analysis. In the shelf-life study only bread baked at 177 C was stored
for 90 days and used to evaluate for APC and C. sporogenes PA 3679.
Aerobic microorganisms in the sample were counted using plate count
agar (PCA) for APC (2). All agar plates as well as FDT (a self-contained
anaerobic system) were incubated aerobically, with PCA plates at 32 C for
48 h (2) and FDT at 37 C for 10 h or longer (1).