Caseinomacropeptide behaviour in a whey protein fractionation process based on α-lactalbumin precipitation

• Published in: Journal of dairy research 2011-05, Vol.78 (2), p.196-202
• Main Authors: Fernández, Ayoa, Menéndez, Violeta, Riera, Francisco A, Álvarez, Ricardo
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; Biological and medical sciences; Caseins - chemistry; Chemical Fractionation - methods; Chemical Precipitation; Food Analysis; Food industries; Fundamental and applied biological sciences. Psychology; Lactalbumin - chemistry; Milk - chemistry; Milk and cheese industries. Ice creams; Milk Proteins - chemistry; Peptide Fragments - chemistry; Terrestrial animal productions; Vertebrates; Whey Proteins
• ISSN: 0022-0299; 1469-7629
• DOI: 10.1017/S0022029911000136

This work studied the behaviour of caseinomacropeptide (CMP) in a whey protein fractionation process based on the selective precipitation of α-lactalbumin (α-la) in an acid medium. Three different acids (hydrochloric, citric and lactic) and different operating conditions (protein concentration, temperature and pH) were considered to perform the precipitation step. Under the optimised precipitation conditions obtained for α-la (pH 4, 55°C, initial α-la concentration around 12 g/l) CMP presents quite similar behaviour to that observed for β-lactoglobulin (β-lg), namely remaining in the supernatant fraction. However, at a lower pH value (3·5) the amount of precipitated CMP increases up to 72% when citric acid is added. This behaviour could be due to the fact that CMP is close to its isoelectric point, which allows a supernatant fraction enriched in β-lg that is almost free from the rest of proteins in sweet whey.