PushLim – Pushing the limits in cheese manufacture and ripening; minimizing the risks through the use of bio-protective cultures

The PushLim Project addresses the challenges facing the dairy industry in terms of an ever-increasing demand for production efficiencies and healthy products while at the same time maintaining high product quality and safety.

By: Grith Mortensen

Such challenges include, (i) the use of elevated temperature ripening in order to accelerate the ripening process (for cost reduction) and (ii) the reduction of salt levels (healthier product). Both measures lead to an increased incidence of cheese defects such as off-flavor, slit/crack formation, biogenic amine formation and blowing. These defects are caused by a disturbance in the normal cheese microflora and through the evolution of an unfavorable detrimental microflora during ripening. Therefore, elevation of the ripening temperature and/or reducing the salt levels can push the cheese ripening in a direction in which serious and costly defects can readily develop.
The focus of this project is to experimentally map the detrimental microflora using genotypic (Whole Genome Sequencing) and phenotypic analysis methods, and to use this critical information to select the most suitable bio-protective cultures for pushing the “no defect” limit beyond what is normally possible. Is it only through the application of bio-protective cultures that elevated temperature ripening and reduced salt cheese can be safely achieved? Pilot plant and subsequent industrial cheese industrial trials (Havarti and Cheddar) will be performed in order to translate and apply the laboratory experiments into a “real-life” dairy manufacturing environment.

The objectives of the project are as follows:
(i) To map using advanced genotypic and phenotypic analysis methods the microflora of normal cheese (control), elevated temperature ripened cheese and reduced salt cheese.
(ii) To characterize and quantify and quality and safety risks (i.e. defects such as off-flavors, silt/crack formation, biogenic amines, blowing) associated with elevated temperatures ripening and salt reduction in cheese.
(iii) To experimentally determine through the use of cheese trials the “no defect” limit in cheese ripening.
(iv) To screen, select and apply bio-protective cultures in order to extend the “no effect” limit in ripening.

Project period: February 2018 - December 2021

Budget: 6.110.000 DKK

Financing: Milk Levy Fund, University of Copenhagen, Arla Foods

Project manager: Fergal P. Rattray

Institution: Department of Food Science, University of Copenhagen

Participants: Department of Food Science, University of Copenhagen, Arla Foods Amba, and producers of bio-protective cultures 




Møller C.O. de A., Christensen, B.B., and Rattray, F.P. (2021). Modelling the biphasic growth of non-starter lactic acid bacteria on starter-lysate as a substrate. International Journal of Food Microbiology 337 (108937), 1-12. https://doi.org/10.1016/j.ijfoodmicro.2020.108937

Møller C.O. de A., and Rattray, F.P. 2021. Histamine-forming ability of Lentilactobacillus parabucheri in reduced salt Cheddar cheese.  Food Microbiology, Vol. 98, 103789, 2021. HTTPS://DOI.ORG/10.1016/J.FM.2021.103789.

Møller C.O. de A., Ücok E. F., Rattray, F. P. (2020) Histamine forming behaviour of bacterial isolates from aged cheese. Food Research International. https://doi.org/10.1016/j.foodres.2019.108719

Møller C.O. de A (2020) The complexity of bacterial interaction in cheese ripening. Nyt om osteproduction, Mejeriteknisk Selskab, Billund, January 2020.

Møller C.O. de A (2018) Bioactive compounds as marker of quality and safety in fermented foods. Oral presentation. In: Final Program and Abstract Book, 1st ICBC International Conference on Bioactive Compounds, November 22sd-23rd 2018, Campinas-SP, Brazil.