Chèvre cheese

“Chèvre” or goat cheese is a food term used to designate cheese made out of goat milk.

Goat milk differs from cow milk in a way of being lower in fat. Fat contents represents 4% of the total composition of cow milk when only 3.44% for goat milk.

Goat milk contains 30,8g/ kg of proteins. It is important to quantify it because it represents the casein concentration. Casein is a conjugated protein, it will form micelles by binding with phosphate groups. Those groups will then bind calcium, which is important for micelles structures. The micelles will later form aggregates that is essential to cheese production. Proteins have a preponderant role and are essential to cheese making process. Casein can represent up to 70% of the total amount of proteins in goat milk. But all caseins in milk cannot form micelles as a part of it is lost in the aqueous phase.

Casein can be found in milk under four different types:

- α(s1) – Casein: low concentration in goat milk making it more digestible than cow milk.

- α(s2) – Casein: major casein proteins with (s1) – Casein.

- β- Casein: more hydrophobic than caseins and very sensitive to calcium concentration.

- κ- Casein: it is found on the surface of the casein micelles (hairy layer) and is a huge factor concerning the cheese making process.

Casein micelles structures will lead to aggregation due to several type of interactions:

- Van der Waals interactions will cause aggregation under all circumstances.

- Electrostatic interactions will create a repulsive force that will vary with pH.

- Steric interactions will also create a repulsion force due to κ- Casein on the surface of the micelle. Casein is important to the functional behavior of dairy products.

Whey proteins are the one that will remain after the coagulation of casein micelles. Those proteins will not coagulate but form a liquid during the process of cheese making. They are non-desirables products in cheese. However, they represent 20% of protein in goat milk. Whey contains the most part of lactose.

Goat milk contains less fat than cow milk. In the process of cheese making, it is necessary to obtain not the largest amount of fat possible as it is for proteins. Instead, the amount of fat needs to be controlled because fat can impact the cheese making process: a concentration that is too low in fat content can be a reason the cheese won’t meet regulations expectations and a too high concentration can limit the process and create a non-usable unit. Fat content in milk is represented by fat globules. Phospholipids forming a tri-layer and associated substances such as cholesterol will create the membrane that retain the triglycerides present in the middle of the fat globule. Triglycerides are fatty acids (saturated and unsaturated) that represent 98% of the total of fat contents.

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