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

Abstract

Milk pre-concentration by nanofiltration (NF) was proposed for fresh Quarg-type cheese manufacturing. NF process modelling by means of model solutions showed that transmembrane pressure and flow velocity had a clear effect on both permeation flux and lactose retention, that a rise in temperature resulted in an increase in permeate flux and a decrease in lactose retention, and 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 results from model solutions. Quarg obtained using milk NF retentates was naturally sweeter (61.52 ± 4.30 g·L-1 lactose) than traditional fresh cheese 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, required an easier treatment than normal Quarg acid whey.