Black Iberian pigs are a distinctive dark-coloured pig that is native to southern Spain. The animal’s meat is revered for its distinct flavour, which is attributed to a diet of foraged forest foods that results in a high fat content. To preserve the various cuts of Iberian pork loin, producers use a combination of salts and nitrites, but with the European Union introducing new regulations to reduce nitrates in foods, the industry is under pressure to find healthier solutions.
The European Regulation 2023/2018 was introduced in October 2023 targeting lower use of nitrates and nitrites in foods, prompted by scientific evidence pointing to the fact that high levels of these substances can have negative health implications in humans, including acting as a carcinogen. One recent study review specifically cited an increased risk of colorectal cancer linked to nitrite in processed meats.
New EU regulations limits nitrites in processed meats
The new regulations determine that Iberian pork processors need to reduce the amount of nitrites contained in the loins by a minimum of 10% if they are to comply with guidelines, which are expected to come into force in 2026.
To tackle the problem the team of scientists from the University of Cordoba looked back on research that had been carried out 10 years ago. Back then, a team of microbiologists isolated a collection of yeasts that had developed in Iberian pork loin during the maturation process, finding that the yeast altered the characteristics of the final product.
Building on this, the team identified one strain of yeast in particular, Debaryomyces hansenii, which appeared to have preservative properties.
Isolated strain of yeast demonstrates preservative properties
“Debaryomyces hansenii is a non-conventional yeast with known biocontrol possibilities. It can be found in many environments and is the most frequent yeast isolated in sausages and dry meat products. The LRC2 strain used in this work is an isolate from Iberian pork loin, characterised biochemically and molecularly,” according to the study findings, which are published in the Journal of Food Control.
Replacing the nitrite and salts with this strain of yeast, the scientists saw a significant difference in outcomes. "We have seen that, through the application of this yeast, we can prevent other unwanted microbes from appearing," said Professor José Ramos, lead scientist for the research.
The researchers evaluated the strain in the labs using a volatile compound inhibition assay that is responsible for both the loin’s aroma and also has an ability to inhibit fungi. The yeast strain was tested alongside a fungus known to impact the loins and found that the fungus grew less, without any kind of intervention.
Determining the yeast strain’s preservative properties
For the final phase of the research, the team inoculated a batch of Iberian pork loins from the Navalpedroche company, located in Cordoba Provence, testing it for bacteria and fungus using ISO standards for food quality and microbiology.
Vital to the research task was to make sure that the distinctive flavour characteristics remained in place, while also ensuring that the nitrite levels were significantly lowered. The research team says its findings confirmed that the nitrite levels were significantly reduced, but that further research would have to be conducted to ensure the flavour was not impacted.
"Using this yeast, in particular, allowed us to lower the levels of nitrite and salt, and maintain food safety and the characteristics of the Iberian pork loin. At the flavour level, however, we did not fully meet the market's needs," said Franscisco Ruiz, a member of the research team.
The team says that while working on the impact on the pork’s flavour, ongoing research would also look at developing the yeast as a natural preservative as well as well as providing a means of reducing both salt and nitrites in a number of applications.
