Writing in its US patent filing, the Mexican food hygiene specialist said there was an increasing need to address food safety issues in the country, particularly in fresh, pre-cooked and fermented meats.
Processing gaps and poor sourcing
Traditional processing methods, it said, especially for fermented and stuffed meat products, along with poor sourcing in the sector from non-certified slaughterhouses, was a cause for concern regarding the development of pathogenic bacteria, like Listeria monocytogenes.
In Mexico, for example, most stuffed products like ham, mortadella and sausages were created from a paste and cooked in water or steam without the necessary high pressures and temperatures needed to sterilize the food product, it said.
“There is a high incidence of gastrointestinal diseases and deaths caused by these reasons in our country,” it said. “In the Mexican Republic, one of the most important health problems is constituted by gastrointestinal diseases, of which salmonellosis occupies a relevant place.”
Whilst use of lactobacilli strains were often used during processing to improve color and aroma, Química Rosmar said not all strains provided natural protection against pathogens.
The sequencial culture method
Química Rosmar said it had developed a culture sequencing method that narrowed down a handful of lactobacilli strains - from meat and plant origins - with a strong “antagonistic capacity” against pathogenic and spoilage microorganisms.
The method, it said, was quicker and easier to implement than traditional assay testing: each strain was observed in a “meat stimulation medium”, rather than in situ and results were then harmonized with assay test findings to confirm the antagonistic potential of each lactobacilli strain.
“The culture sequencing method seems to be a useful tool to quickly select cultures of lactobacilli which are good candidates for bioprotection of meat,” it wrote.
From a total of 60 lactobacilli strains, seven were selected and used in isolated amounts as “biopreservative compositions” to inoculate the meat products, it said.
Química Rosmar said these lactobacilli blends could “competitively inhibit” the growth of unwanted pathogens and spoilage bacteria in meats like fresh chicken, pre-cooked ham and sausages, improving shelf-life and overall food safety of the final product.
The strength of the strain
Each lactobacilli strain and subsequent microbial consortium was then tested on raw and processed meat products with adapted application methods, although in all cases a 'broth' composition was applied.
For fresh chicken, the lactobacilli composition was blended with organic acid, inoculated and used in a “marinade” form – poured over the fresh, skinless chicken ahead of packaging.
When blended with acetic acid at 1%, the shelf-life of the chicken could be increased by 40-50%, meaning the refrigerated chicken would be suitable for consumption up to 11 days after packaging rather than seven.
Testing was also done with spoiled sausages that had been incubated at 35-45°C for 48 hours to encourage growth of spoilage microorganisms. Results showed the lactobacilli composition “protected” the product from the typical white film or 'slime' associated with spoiling. Similar results were seen in ham.
However, it said lactobacilli strains to counter growth of spoilage microogranisms in meat must be used in parallel with other preservation methods, like use of lactic acid.
The best results with pre-cooked sausage products were seen when the product was immersed in the lactobacilli broth after cooking, just ahead of vacuum packing and refrigeration. Following this method increased shelf-life by 30% - from four weeks to six.
For pre-cooked ham, the solution of bacterial consortia had to be sprinkled onto each slice before vacuum packing and refrigerating at a volume of about 5 mL per slice, increasing shelf-life by around 25% or two weeks in storage terms.
Source: WIPO Publication No. 20180000101
Published: January 4, 2018. Filed: December 18, 2015.
Title: “Biopreservation composition based on facultative heterofermentative lactobacteria for preventing and controlling the spoilage of fresh and cooked meat products”
Authors: Química Rosmar, S.A. de C.V. - R. Martinez Romero et al.