Teagasc goes genomic to boost flavour in dairy
in dairy products - and enhancing the country's technological
standing in international R&D.
"This landmark project is key to building a critical mass in genomics of starter cultures and will place Moorepark at the forefront of international developments in the rapidly evolving area of applying genomics to traditional and innovative food systems," said Dr. Michael Callanan from the Moorepark Food Research Centre (MFRC).
The food industry is Ireland's largest indigenous industry, employing over 40,000 people and encompassing more than 700 companies. The most recently available figures (2002) set annual output at over €16bn, with exports of €6.7bn.
And Teagasc, the Irish Agriculture and Food Development Authority, is continuing to fund projects such as the major new project under way at the MFRC with the objective of determining the complete DNA sequence of a unique cheese making bacterium.
Of particular interest to the dairy industry, Callanan told FoodNavigator, are members of the Lactic Acid Bacteria (LAB) that give key flavour, texture and preservation qualities to a range of fermented foods.
Research has focussed on Lactobacillus helveticus DPC 4571, which was originally isolated from cheese whey. The genome sequence, found to code for about 2,000 genes, was determined in collaboration with a commercial biotechnology company.
"Improvements in the flavour of Cheddar cheese manufactured with this bacterium have consistently been observed in both pilot and commercial trials and it has also been used successfully in the development of new cheese varieties," said Callanan.
"Two particular traits are thought to contribute significantly to the flavour-enhancing abilities of DPC 4571, a potent proteolytic system and the rapid autolysis of the strain in the cheese matrix. Degradation of the major milk protein, casein, by the bacterial proteinases and peptidases enzymes generates important flavour compounds."
Cheese manufactured with DPC4571 have a sweeter, less bitter flavour, said Callanan, which is associated with, amongst other things, higher levels of free amino acids.
"Starter cultures in general are responsible for producing other flavour compounds such as free fatty acids, alcohols, aldehydes, esters, ketones and it is the combination or balance of all these compounds that produces the characteristic flavour associated with a strain."
To enhance flavour development in cheeses, six key metabolic functions are important, explained Callanan. These include proteolysis, amino acid metabolism, lipolysis, exopolysaccharide production, cell lysis and citrate metabolism.
"The aminotransferases, proteinase and peptidases are all involved in the breakdown of the casein and metabolism of its constituent amino acids and these processes contribute significantly to the production of flavour compounds," he said.
Nineteen genes are said to have been selected for preliminary investigation based on potential for commercial applications in cheese flavour development.
"The products of all these genes will be investigated with a view to specific commercial applications such as enzyme modified cheese production, generation of bioactive peptides and tools for future starter culture design," said Callanan.
Callanan told FoodNavigator that the driver behind the project had been flavour, but that expansion to look at the potential nutritional enhancements was also on the horizon, with enhanced understanding of probiotics.
"Comparison of the sequenced probiotic lactobacilli and the DPC 4571 cheese culture should provide insight into the flavour-enhancing abilities of DPC 4571 and the mechanisms of intestinal colonisation and health promotion of the probiotic strains," he said.
And the technology may not be just applicable to dairy. "As for other non-dairy applications we would envisage the enzymes from the strain as having applications in those areas, not necessarily the strain itself," said Dr. Callanan.
