Samples taken over the course of this study included ingredients,
finished product, debris samples (including food debris
taken along the production line), and environmental samples
(drain samples, food-contact swab samples and non-food-contact
swab samples). Meat ingredient samples were obtained from the
refrigerated holding area and dried ingredients were taken from
storage, after arrival at the facility. Food debris samples were procured
during production runs, and comprised post-cooking food
matter taken from the area around the processing lines. Samples
were collected over a period of 23-months, and comprised routine
testing, along with targeted non-routine sampling (such as sampling
of ingredients, the food preparation area, and the final packing
area). A total of 6785 individual samples were tested. These
were stratefied into one of five categories/areas (and denoted
accordingly) as follows: ingredients (I); food preparation (FP);
cooking and packing (CP); bulk packing (BP); and final product (P).
The CP area was zoned separately from other areas of the facility,
with controls being placed on incoming staff and materials. A total
of 73 drains were sampled (11 in the FP area, 59 in the CP area, and 3
in the BP area).
2.2. Listeria