How to build a better sausage
Italian research interrogates the role of bacteria in making fermented meat. Andrew Masterson reports.
It is a question that has perhaps occupied significant parts of humanity for thousands of years: how do you create a tasty fermented sausage?
The popularity of prepared meats such as salami and sopressa attest that love of such sausages runs deep, and the passionate debates about what type made by which manufacturer or farmer tastes best is eloquent testimony to the role these meats play in many cultures.
Talk to most foodies, and they will tell you that homemade fermented sausages are preferable by far. Talk to them in a more detail, however, and the honest ones will admit that homemade salami brings with it a significant risk of food poisoning.
Some commercially prepared fermented meats have been the cause of severe, even fatal, poisoning, but any sober analysis will reveal the risk to be much, much lower.
However, that same analysis often concludes that commercial salami, while safer, sometimes tastes kind of yuck.
The difference in the taste profile of commercial and homemade fermented sausage is due to bacterial population that generates the process. At home, many sausage makers prefer to let the process kick-start naturally, relying on bacteria already present in the meat to get on with the job.
The approach is very much hit and miss. Sometimes it results in beautiful meat, cured for three months, hung for six, then served to adoring family. And sometimes it results in nothing at all, or a rotten smelly mess, or six people admitted to hospital.
Commercial makers, not surprisingly, have neither the time nor the insurance coverage to trust their product to vagaries of nature. Instead, they use industrially prepared inoculants, which ensure every kilogram of meat receives exactly the same introduced microbiota – and, not coincidentally, gets the fermenting done faster.
Now, a team of Italian microbiologists, writing in the journal Applied and Environmental Microbiology, has investigated the bacterial mechanisms that underlie the sometimes starkly different taste profiles between homemade and commercial sausages.
The researchers, led by Luca Cocolin from the University of Turin, found that commercial starters tended to produce meat that had higher acidity than “spontaneously” fermented meat. The result was a poorer taste.
To find out what was causing the problem, the researchers sequenced the bacterial DNA found in the meat. They also used a combination of gas chromatography and mass spectrometry to measure metabolites produced during fermentation.
They found significantly different bacterial populations at work. In the commercial product, the population of lactic acid bacteria species such as Lactobacillus sakei, and L. curvatus, while essential, was notably high. The lactic microbes were also joined by significant numbers of Staphylococcaceae bacteria.
In the “spontaneous” product the lactic acid bacteria were still present, but at lower densities. This meant that over all bacterial activity was lower and fermentation thus slower.
"The over-activity of the starter culture-inoculated sausages resulted in increased acetic acid and short chain fatty acids," says Cocolin. He adds that this produces meat that tastes “pungent, vinegar, cheesy, and weedy”.
The slower fermentation of homemade salami, in contrast, resulted in more medium and long chain fatty esters, which made the flavour reminiscent of “fruity wine, waxy sweet apricot, and banana brandy”.
Cocolin’s team hope the research will allow meat-manufacturers to better construct and control their added inoculants, resulting in salami that is every bit as good as the stuff Nana used to make – but won’t make you throw up in the middle of the night.