Assessment of the microbial safety and quality of cooked chilled foods and their production process

Abstract

Refrigerated processed foods of extended durability (REPFEDs) are a heterogeneous group of food products. This study assesses the microbial safety and quality along the production process in five REPFED companies. Samples were taken of raw materials (n=123), intermediate products (n=123), end products at production day (n=45) and at end of shelf life (n=90), food contact surfaces (n=226) and worker's hands/gloves (n=92). Samples are analysed for total psychrotrophic aerobic count, aerobic spore count, sulphite reducing Clostridia, Bacillus cereus and Listeria monocytogenes. Both L. monocytogenes and B. cereus were detected on the raw materials. Nine of 72 raw materials tested were positive (in 25g) for L. monocytogenes and all but one of these raw materials were raw or minimally processed animal products. Three of 123 raw materials contained high counts (>4log CFU/g) of B. cereus, all of these samples were dried herbs. During production both food contact surfaces (90/226) and gloves (43/92) contained increased levels of total psychrotrophic aerobic counts (≥3log CFU/25cm(2)). This points out a potential source of bacterial recontamination. However, only a four and six of 223 food contact surfaces were positive (per 25cm(2)) for L. monocytogenes and B. cereus respectively. None of the gloves sampled contained L. monocytogenes and only 2 sets of gloves were positive for B. cereus. Of the 123 intermediate products tested twelve tested positive for L. monocytogenes (in 25g) and 5 showed elevated counts of B. cereus (ca. 2.5log CFU/g). Despite the presence of L. monocytogenes in the raw materials, the production area and in some of the intermediate products, none of the end products were positive for L. monocytogenes and only 9 of 135 samples (6.7%) showed to have low numbers of B. cereus (<2.7log CFU/g). This results show that the current pasteurization processes and the food safety management system are adequate to guarantee the production of microbiologically safe foods but that some improvements can still be made with regard to supplier selection, cleaning and disinfection, hygiene training and setting the shelf life duration.