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Influence of goat milk composition and level of αS1-casein on the yield of fat-free fresh cheese model.

R. A. Ibáñez

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06-23-2020

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Abstract:

T31
Influence of goat milk composition and level of αS1-casein on the yield of fat-free fresh cheese model.
F. Pinto1, J. L. Riveros2, R. A. Ibáñez*2,3. 1Pontificia Universidad Católica de Chile, Facultad de Agronomía e Ingeniería Forestal, Escuela de Graduados Santiago, Chile, 2Pontificia Universidad Católica de Chile, Facultad de Agronomía e Ingeniería Forestal, Departamento de Ciencias Animales Santiago, Chile, 3University of Wisconsin-Madison, Center for Dairy Research Madison, WI.

In goat milk, the level of expression of αS1-casein (CN) is associated with animal genetics and relates to the content of total solids of milk and cheese yield. In Chile, goat production is mainly extensive, non-specialized, and with mainly Creole animals with high genetic variability in both production and levels of total solids in milk. In recent years, goat milk production has experienced a considerable development and technification, forcing the genetic selection of herds toward increased production and yields, as required by market needs. In this study, we analyzed the relationship between the composition and levels of αS1-CN in goat milk with the yield of fat-free fresh cheese made on a laboratory scale. A goat dairy farm located in the dryland area of Central Chile (33°32′45″ S, 71°35′00″ W, 154 m altitude) and comprised by 87 goats, was used for this study. Individual milk samples were collected at 200 ± 7 d (mean ± SD) of lactation and analyzed for composition, somatic cell count, levels of individual caseins by reversed-phase high performance liquid chromatography and cheese yield (kg cheese/100 kg milk) obtained from a miniature cheesemaking laboratory model based on milk composition and using 40 g of skim milk. Variables were evaluated according herd phenotype: Alpine (n = 4), Chilean Creole (n = 7), Crossbreeds (n = 20) and Saanen (n = 56); and levels of αS1-CN in milk: high (>15% αS1-CN/total CN), medium (10—15% αS1-CN/total CN), low (5—10% αS1-CN/total CN) and very low (0—5% αS1-CN/total CN). A positive correlation (r = 0.768; P < 0.05) was found between protein content of milk and cheese yield. However, a low correlation (r = 0.243; P < 0.05) was found between the level of αS1-CN in milk with cheese yield. These results suggest that standardization of cheesemaking protocols based on milk composition may reduce differences in cheese yield due to genetic variability of individuals in a herd.

Keywords: αS1-casein, goat milk, cheese yield.