Meat Processing Plant Microbiome and Contamination Patterns of Cold-Tolerant Bacteria Causing Food Safety and Spoilage Risks in the Manufacture of Vacuum-Packaged Cooked Sausages

Abstract

bRefrigerated food processing facilities are specific man-made niches likely to harbor cold-tolerant bacteria. To characterize this type of microbiota and study the link between processing plant and product microbiomes, we followed and compared microbiota associated with the raw materials and processing stages of a vacuum-packaged, cooked sausage product affected by a prolonged quality fluctuation with occasional spoilage manifestations during shelf life. A total of 195 samples were subjected to culturing and amplicon sequence analyses. Abundant mesophilic psychrotrophs were detected within the microbiomes throughout the different compartments of the production plant environment. However, each of the main genera of food safety and quality interest, e.g., Leuconostoc, Brochothrix, and Yersinia, had their own characteristic patterns of contamination. Bacteria from the genus Leuconostoc, commonly causing spoilage of cold-stored, modified-atmosphere-packaged foods, were detected in high abundance (up to >98%) in the sausages studied. The same operational taxonomic units (OTUs) were, however, detected in lower abundances in raw meat and emulsion (average relative abundance of 2% ؎ 5%), as well as on the processing plant surfaces (<4%). A completely different abundance profile was found for OTUs phylogenetically close to the species Yersinia pseudotuberculosis. These OTUs were detected in high abundance (up to 28%) on the processing plant surfaces but to a lesser extent (<1%) in raw meat, sausage emulsion, and sausages. The fact that Yersinia-like OTUs were found on the surfaces of a high-hygiene packaging compartment raises food safety concerns related to their resilient existence on surfaces. R efrigeration is used throughout the modern food chain to ensure the safety and quality of perishable products. Chilling has also been extended to food processing facilities to ensure that food manufacture complies with the legislative requirements governing maximum food temperature. Perishable food is usually packaged under a carbon dioxide-containing modified atmosphere to suppress bacterial growth. These modern food manufacturing practices have changed the order of prevalence of food-borne bacteria. Instead of aerobic Gram-negative bacteria, (facultatively) anaerobic Gram-positive bacteria prevail in modified-atmosphere-packaged (MAP) foods (1). In addition to refrigeration, the daily cleaning and sanitizing procedures used at the processing facilities might lead to the resilience of certain microbes and thus persistent contamination.Hygiene in a food processing facility is monitored through an internal control procedure, including hazard analysis of critical control points. The manufacturer is responsible for guaranteeing the safety and quality of its products during the shelf life set for each respective product. In routine hygiene monitoring, the microbiological quality of the raw materials, cleanliness of the surfaces, and quality of the end products are included in these internal control protocols. Bacterial contaminat...

Overlap of Spoilage-Associated Microbiota between Meat and the Meat Processing Environment in Small-Scale and Large-Scale Retail Distributions

“…The environmental microbiota from processing plants have often been addressed as sources of microbes that potentially affect the quality attributes of meat (1,12,13). Indeed, several studies demonstrated that the microbiota involved in food-processing steps are often found on processing surfaces or tools (11,12,(14)(15)(16)(17), underlying the importance of hygienic practices in influencing the food microbiota.…”

“…Indeed, several studies demonstrated that the microbiota involved in food-processing steps are often found on processing surfaces or tools (11,12,(14)(15)(16)(17), underlying the importance of hygienic practices in influencing the food microbiota. However, no studies have investigated the differences in the contamination types and levels between small-scale retail distribution (SD) and large-scale retail distribution (LD) facilities.…”

Reducing Salt in Raw Pork Sausages Increases Spoilage and Correlates with Reduced Bacterial Diversity

“…This study also illustrated the role of spices as a source of spoiling bacterial species and demonstrated the important role of sodium-and acid-based preservatives (sodium lactate and sodium diacetate), first, in reducing spoilage of sausages, and second, in hindering the growth of the dominant spoilage bacteria Lactobacillus graminis and Carnobacterium divergens. More recently, Hultman and coworkers (2) showed that contamination during the initial preparation of cooked sausages is a key point that can influence spoilage dynamics during storage. However, they also underlined the importance of temperature and other conditions during distribution and storage in influencing the rate of spoilage.…”

“…Depending on the degree of salt reduction, bacterial populations may remain quite stable, sometimes even with a decreased incidence of bacteria that cause meat spoilage (17). Furthermore, food microbiologists have recently highlighted the weaknesses of plating methods in assessing the overall diversity of potential meat spoilers (1,2,(19)(20)(21), in that the most abundant (often psychrotrophic) species are among the hardest to cultivate using conventional media. If the effect of salt reduction on the meat microbiota is to be thoroughly assessed, it is necessary to analyze the whole bacterial community, as the meat microbiota is often divided into a core dominant population and a productspecific subdominant population (20).…”

“…From pork slaughtering to final packaging, their manufacture requires several steps (meat cutting, blending, and stuffing), with each a potential source of bacterial contamination (1)(2)(3). Raw pork sausages are thus very sensitive to spoilage unless specific treatments are applied to prevent their rapid sensory degradation.…”