Differences in bovine and caprine cheese production

Monday, July 21, 2014: 11:15 AM
2208 (Kansas City Convention Center)
Katie Wolf , University of Kentucky, Lexington, KY
Jeffrey M Bewley , University of Kentucky, Lexington, KY
Abstract Text:

The dairy goat cheese market is the primary milk-based income source for dairy goat producers.  Efficient cheese production is more challenging with goat milk than cow milk.  These challenges arise from structural and molecular characteristics unique to goat milk.  Goat milk has a lower pH than cow milk, which results in differences in the acidification process for initializing curd formation.  Another factor is the smaller fat globules of goat milk, which result in a natural homogenization effect and greater difficulty in separating smaller particles.  Less particle separation results in lower cheese yields.  Possibly the most significant difference is seen in the alpha S1-casein frequencies across the goat population when compared to the cow population.  Casein is the major protein in milk and is essential for cheese production.  The primary casein subclasses are alpha and beta caseins.  In cow milk, the alpha caseins are more prevalent than any others, whereas in goat milk beta caseins are more typically observed.  Alpha S1-casein, in particular, is associated with higher solids-non-fat content than any other casein class, but it is among the least common goat milk proteins.  This means lower cheese yield because the most important cheese protein is not the most prevalent in goat milk.  Presence and frequency of alpha S1-casein is primarily genetic with 17 alleles identified.  Further variation in alpha S1-casein expression exists between dairy goat breeds, with the Swiss breeds expressing the weakest alpha S1-casein alleles compared to African and American breeds, which have a higher alpha S1-casein frequency.  The breed relationships to cheese proteins suggest that the first step in achieving good cheese yields is selecting goats of the correct breeds.  Additional problems to be combated are the higher SCC seen in goats compared to cows, reducing curd formation ability, and a greater variation in diet with most goat herds compared to cow herds which can cause inconsistent yields, textures and flavors.  Cheese recipes can be modified to optimize yield from goat milk by adding more rennet, using less starter, and maintaining a lower temperature during the cheese making process.

Keywords: goat, alpha S1-casein, cheese