This PhD project falls within the larger scope of the NWA-ORC project named ‘Animal-free milk proteins’, which aims to create an alternative for milk-based products by the following stepwise approach:
- The casein proteins as they are found in bovine milk are to be produced by a microbe such as yeast through precision fermentation. This is the subject of another PhD candidate (Laura Iaria).
- These microbial proteins are to be assembled with calcium into larger structures, called micelles, to resemble how native caseins are found in milk. Another PhD candidate (Zekun Fan) is investigating the assembly method, based on Schmidt, Koops et al. (1977).
- The assembled microbial casein micelles are to be used to produce cheese which should have equal organoleptic and digestive properties as the bovine cheese, which is the topic of this PhD.
The long-term goal of this approach is that traditional dairy products can be made without the need for animal rearing, leading to the concept of animal-free dairy.
Although animal-free dairy may be a sustainable and nutritious alternative to traditional dairy, no experimental data has been published on product creation from microbial casein. Therefore, it is not yet possible to conclude that a dairy product like cheese, which relies heavily on casein for its characteristic structure, flavour and digestion, can be made animal-free. The objective of this PhD project is therefore to investigate the cheese-making ability of microbial casein in comparison to bovine casein, taking into account the need for micelle assembly.
Casein micelles of different origin will be studied: native bovine, reassembled bovine (RCM) and assembled microbial (ACM) casein micelles. These will be compared in the multiple stages of the life-cycle of a cheese, starting with a milk-like system, going through curdling and ripening, and ending with digestion, see Figure 1. To be able to make connections between the different systems and stages of the life-cycle of cheese, wherever possible the same methods will be applied. For example, oscillatory rheology will be used to study both curdling and milk digestion, and SDS-PAGE will be used to follow proteolysis during both cheese ripening and cheese digestion.
1. Glaser, J., P. A. Carroad and W. L. Dunkley (1980). "Electron Microscopic Studies of Casein Micelles and Curd Microstructure in Cottage Cheese." Journal of Dairy Science 63(1): 37-48.
2. Schmidt, D. G., J. Koops and D. Westerbeek (1977). "Properties of artificial casein micelles. 1. Preparation, size distribution and composition." Neth. Milk Dairy Journal 31: 328-341.