Academics based at the UK universities of Nottingham and Northampton are collaborating with specialist blue-cheese maker Stichelton Dairy in Nottinghamshire (along with other industry stakeholders) on the £79,000 project to examine the role of secondary flora in flavour development.
Microorganisms or ‘starter cultures’ are added to milk during cheese manufacture, with additional mould cultures added during 'needling' (while the cheese is ageing) but the final ‘flora’ of cheese develops during ripening and contains micro-organisms not orginially added during production, known as secondary flora.
Secondary flora: hero and villain
Study leader Dr. Konstantinos Gkatzionis, from the University of Northampton, told FoodNavigator.com that his team are mid-way through a six month study examining how secondary flora (mainly yeasts arising due to environmental factors) contribute to flavour development and allow blue veins to develop: such flora contribute to cheese flavour in a positive sense, but also produce bitter smells and poor formation of blue veins.
"The study has three different dimensions: firstly, understanding, rather than looking to alter, the flavour-development mechaism caused by secondary flora. Secondly, strains found to be beneficial to flavour may be used in addition to a starter bacteria or [for some blue cheeses] mould cultures, to improve the taste," said Gkatzionis.
"Thirdly, if certain compounds inhibit mould growth (and we believe they could be of a protein nature) then they can either be removed or used in other types of cheese where this is desirable, as natural additives."
Joe Schnieder, director, Stichelton Dairy (which makes classic blue cheeses from unpasteurised milk) said he believed other participants were also based in the UK's Stilton protected designation of origin (PDO) area, within the 'three counties' of Nottinghamshire, Derbyshire and Leicestershire.
“The research will probably principally benefit cheese producers who use pasteurised milk," said Schneider.
"People have strong opinions, but cheese made with this is essentially a blank slate, since the microflora have been killed so are not contributing to flavour.You have to add them them in later on, so examining the components of secondary flora is of great interest.
“For us it’s a lot more about understanding the processes involved, although we are interested in the components that inhibit ‘blueing’ [blue veins in cheese that contribute to flavour] since if this isn’t happening it’s a problem for us.”
How do cheese micro-organisms interact?
With the academic team examining the influence of local environmental factors affecting flora formation on rinds (and taste, texture, smell accordingly) Schneider said: “It would be nice to know more about what is happening, and look at whether it is a process we could control in future. At the moment it's fair to say that we shepherd, rather than control, flavour development with secondary flora.”
“When we started out, everyone thought the flora in milk alone contributed to flavour, but no-one really considered bacteria on rinds – aside from lactic bacteria upon them – that were not originally present in milk.”
Nottinghamshire-based Food and Drink iNet (which helps develop links between industry and academe) is funding the research under an EU programme.