The pre-concentration of milk by nanofiltration in the production of Quarg-type fresh cheeses

Milk pre-concentration by nanofiltration (NF) was proposed or Fresh Quarg-t ype cheese manufacturing. NF process modelling by means of model solutions showed that transmembrane pressure and flow velocity had a clear effect on both permeation nux and lactose retention, that a rise in temperature resul ted in an increase in permeate flux and a decrease in lactose retention, an d that monovalent ion retention depended heavily on the concentration. Milk was concentrated 2 to 3 times by NF. Permeation fluxes were in a range of 10 to 41 kg.h(-1).m(-2) and solute retentions were in accordance with the r esults from model solutions. Quarg obtained using milk NF retentates was na turally sweeter (61.52 +/- 4.30 g.L-1 lactose) than traditional fresh chees e and had a high calcium content (2.01 +/- 0.33 g.L-1) and no bitter taste. Whey had a higher total solids and lactose content and, therefore, require d an easier treatment than normal Quarg acid whey.