Fig. 1 presents the experimental design for preparation of sausage
batter illustrated for one of the four bacterial conditions (DT12,
exponential-phase cells). In step i, each of two 1500-g batches of
minced meat, consisting of meat pooled from up to three different packages
from the same manufacturer and the same production date, was
mixed with 30 ml S. Typhimurium culture prepared according to
Section 2.1, and thoroughly blended by hand massage. The 1500-g
batch was divided into lots of 375 g: one lot was used unfrozen and
processed immediately (0) and the other two lots were frozen at
−18 °C for 7 and 35–47 days (N35 days). Each of the four bacterial conditions
was repeated three times. Different packages of meat were used
for the replicates.
In step ii, the frozen lots were defrosted at 5 °C overnight before
adding the sausage ingredients NaCl (3% wt/wt), dextrose (0.7% wt/
wt) and NaNO2 (either 0 or 100 ppm) according to the design. In step
iii, the sausage batter was then divided into two portions (180 g)
where one portion had starter culture added (+) or not (−). A starter
culture, commonly applied in sausage production (Bactoferm F-1, Chr.
Hansen; a mixture of Staphylococcus xylosus and Pediococcus
pentosaceus), was used according to the manufacturer's
recommendations