Marinades and shelf life
A combination of packaging with CO2 and marinating gives the best shelf life, concludes Bjørn Schirmer. Bjørn Schirmer has been investigating how antimicrobial substances found in fruit, spices and herbs can be used in marinades to increase the shelf life of meat and fish. That was when he came across Lactobacillus algidus.
Bjørn Schirmer has been investigating how antimicrobial substances found in fruit, spices and herbs can be used in marinades to increase the shelf life of meat and fish. That was when he came across Lactobacillus algidus.
That is not to say that nobody has discovered this lactic acid bacteria before, because it is not unknown. But it is difficult to find, because it does not grow in an ambient temperature above 25 degrees and it grows very slowly on normal growth media. The problem with it is that it destroys the quality of the meat.
"We discovered Lactobacillus algidus both on untreated meat and also on several marinated pieces of meat. The bacteria causes the quality of meat to deteriorate quite quickly, so it is important that the industry checks for this lactic acid bacteria in order to maintain quality," says Bjørn Schirmer.
Must be custom made
He has looked at three conditions relating to marinating meat and fish: use of antimicrobial substances, packaging with CO2 and use of inhibiting cultures.
"My conclusion is that there is no single answer when it comes to marinating meat and fish. The marinade must be custom made for each individual product, depending on sensory qualities. Different bacteria react differently to inhibiting cultures and antimicrobial substances, so it is difficult to find a marinade which inhibits all bacteria that might affect quality," says Bjørn Schirmer.
"We found the best effect when combining CO2 packaging and antimicrobial acids. We tested various marinade combinations with varying concentrations of acids at Nortura, which has collaborated in the project together with Tine and Fjordland," explains Schirmer. Parallel with his measurements of the numbers of bacteria in the samples, the industry partners have been testing the sensory qualities. The conclusion from the sensory tests was that antimicrobial acids caused fewer problems with fish than with meat.
On 6 October Bjørn Schirmer had his doctoral disputation. He will continue as a research scientist at Nofima Mat. He will mainly be working with Listeria in relation to cheese production.
A combination of packaging with CO2 and marinating gives the best shelf life, concludes Bjørn Schirmer.