A method for the large-scale isolation of β-casein |
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Authors: | Thom Huppertz Jean-Baptiste Hennebel Therese Considine Shakeel-Ur-Rehman Alan L Kelly Patrick F Fox |
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Affiliation: | 1. Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland;2. Ecole Nationale Supérieure Agronomique de Montpellier, Montpellier, France |
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Abstract: | A method for the large-scale isolation of β-casein from renneted skim milk was developed. The curd from renneted skim milk was dispersed in hot (?70 °C) water to inactivate residual chymosin. The heated curd was subsequently recovered by centrifugation, resuspended in water and incubated at 5 °C, during which β-casein dissociated from the curd; the suspension was centrifuged and the aqueous phase lyophilised. The isolated protein consisted mainly of β-casein, containing a minor amount of γ-caseins and traces of other caseins. Unless chymosin was fully inactivated by heating, some β-casein was hydrolysed at the Leu192–Tyr193 bond. The yield of β-casein increased with incubation time, up to ∼20% of the β-casein present in the milk after 24 h at 5 °C. Reducing milk pH to 5.5 or 6.0, prior to renneting, caused a high level of contamination with αs-caseins. This isolation procedure can be easily scaled-up to an industrial process and the β-casein-depleted curd may be used for the manufacture of rennet casein or processed cheese. |
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Keywords: | β-Casein Isolation Milk |
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