A novel approach to isolation of β-casein from micellar casein concentrate by cold microfiltration combined with chymosin treatment

Filtration is frequently employed in the dairy industry to tailor protein profiles and manipulate the nutri- and techno-functionality of ingredients. One milk protein of particular interest in infant formula is β-casein. However, during the enrichment of β-casein, co-fractionation of κ-casein, as 2–10% of the total protein, is common. In this study, isolation of β-casein from micellar casein using filtration, incorporating chymosin-treatment, was investigated. At 5 °C, casein curd formation can be avoided, allowing the fractionation of liquid streams. Three treatments with chymosin were applied: feed without treatment and feed or permeate treated with chymosin. An average β-casein enrichment of ∼90% (w/w) total protein was achieved. Treatment of feed with chymosin resulted in caseinomacropeptide (CMP)-enrichment. CMP-enriched β-casein showed a wider particle size distribution at 50 °C, and a reduced level of solubility. The novel materials produced may be relevant in applications such as encapsulation, emulsification, infant formula and cheese manufacture.