Microbiological Stability and Overall Quality of Ready-to-Heat Meals Based on Traditional Recipes of the Basilicata Region

Abstract

The quality of ready meals is affected by several factors that may impair stability and nutritional value. In this work, we evaluated the overall quality of four traditional meals (Basilicata region) prepared according to the cook&chill method, packaged in air or modified atmosphere packaging (MAP; 70% N2 and 30% CO2), and stored at 4 °C for seven days. The shelf-life was determined by Listeria monocytogenes challenge testing and inactivation by microwave (MW) heating was assessed. The counts at the production day were excellent in three meals out of four, whereas one had high levels of spoilage and pathogens both as soon as the preparation and after seven days. MAP was partially effective only against the growth of the aerobic mesophilic species, whereas sensory analysis revealed that MAP may preserve many of sensory attributes. The average shelf-life of the meals ranged from 11 to 13 days, however, the potential shelf-life was undetectable in one out four meals, as L. monocytogenes growth was inhibited two days after the inoculum. In the inoculated meals, MW heating provided a partial inactivation (25%) of the pathogen. The overall quality of type the meals was partially satisfactory; post-cooking contaminations may affect the microbial load and reduce the palatability over the storage period and, above all, may involve biological hazards which consumers’ habits may not be able to eliminate.

Prevalence of Listeria monocytogenes and Salmonella spp. in Different Ready to Eat Foods from Large Retailers and Canteens over a 2-Year Period in Northern Italy

“…For the L. monocytogenes, a volume of 0.1 mL of the initial food suspension (25 g of samples enriched with 225 mL of Listeria 1 2 Fraser Broth) was briefly plated in a selective chromogenic medium: rapid L. mono. The final test for the confirmation of suspected colonies was carried out by biochemical testing (Microgen™ Listeria-ID, Camberley, England), whereas, for the testing of Salmonella spp., a 25 g sample was pre-enriched and homogenised in 225 mL of buffered peptone water.…”

“…For both pathogens, the results are expressed as absence/presence in 25 g of the sample material. Xylose lysine Desoxycholate Agar (XLD) 1 24 37 Brilliant Green Agar (BGA) 1…”

“…As a result of changes in lifestyles, the current economic systems, a curiosity for culinary dishes that are diverse and distant from our traditions [1], and, more recently, the effects of the COVID-19 pandemic [2], there has been an increase in the consumption of so-called ready-to-eat foods (RTE). In this regard, in Europe in 2021, the average volume of consumption of RTE meals per person, thus far, amounts to 15 kg.…”