Surface-ripened cheeses have typical tastes and colours, caused by a complex mixture of microorganisms on their surfaces. These microorganisms are transferred from one batch of cheese to another during the ripening period of several weeks (old-young smearing). This procedure carries the inherent risk of contamination of the new cheeses with undesired microorganisms (Listeria monocytogenes, moulds). The risk of Listeria infections could be reduced significantly by using defined surface starter cultures instead of smear cultures. However, complex defined surface starter cultures are not yet commercially available for any red-smear cheese.
In a previous EU RTD project (CT98-4220), in which the majority of the members of the present consortium participated, the feasibility of developing defined surface starter cultures for red-smear cheeses has been investigated. In that project, the surface flora of a particular red-brown smear cheese has been identified and intensively characterised, in particular with respect to the microbiology, flavour compounds, and colour development. Based on these studies, defined starter cultures, resembling as much as possible the original flora were developed. By using these starter cultures in pilot scale cheese production, it was shown for the first time that defined starter cultures can dominate the micro-flora on cheeses ripened in pilot-scale cheese production. All technical methods were developed that are necessary to construct a defined surface starter. However, the starter cultures were not yet of commercial interest because the colour and taste were still different from that of the original smear cheese. Moreover, the growth of the defined starter red-smear cultures was too slow and therefore, moulds could still colonise the cheeses. Dairy and starter culture companies will not change to the use of defined surface starters because the development time of the surface starter was too long and the quality of the final product was not equal to the existing products. As a result, the safety of surface ripened cheeses will not improve, even though evidence has been provided that defined surface starters can be constructed. This makes clear that this new technology can not be commercialised directly and it has to be demonstrated that high quality surface starters can be developed.
To enable dairy and starter culture companies to change to the use of defined surface starters, the development time of the surface starter must be shortened and the quality of the final product must be equal to the existing products. Therefore, in this project it will be demonstrated that such defined starters can be constructed time - and cost-effectively by following a routine procedure: Tailor-made starter cultures for two different red-smear cheese varieties will be developed, evaluated in pilot-scale cheese production, and validated (production technology, cheese characteristics, consumers acceptation). Thereby, this project will bridge the gap between proof of principle, as established in the previous project, and a commercially tangible technology. Deliverables will be: l) safer cheeses; 2) new market for starter companies; 3) better controlled cheese making processes, less losses, more income for cheese companies.
The project will deliver a time- and cost effective standard method with which industrial surface starter cultures for red-smear cheeses can be constructed. The use of industrial surface starter cultures will result in:
- Improved safety of the cheeses;
- A completely new market for starter culture companies. So far, tailor-made starter cultures for red-smear cheeses are not available, because they cannot be constructed time- and cost effectively.
- Better controlled processes for the preparation of red-smear cheeses by industrial companies and decreased losses of batches of cheese, contaminated with Listeria or other undesired micro-organisms. This will result in increased profits for industrial cheese companies. It is envisaged that at the end of the project, each of the two industrial cheese companies involved in this project will have a defined surface starter culture for their specific cheese. These cheeses have been validated with respect to production technology, flavour, colour and consumer acceptation.