Influence of skimmed milk concentrate replacement by dry dairy products in a low-fat set-type yoghurt model system.: Use of caseinates, co-precipitate and blended dairy powders

Yoghurt fortification with caseinates, co-precipitate and blended dairy powders in a low-fat yoghurt model system was studied. These dairy products were characterised for pH, moisture, lactose, mineral and protein fractions. Milk proteins were characterised by polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). Minerals such as Na, Ca, K and Mg were analysed by atomic absorption spectroscopy. Yoghurts were formulated using a skimmed milk concentrate as a milk base enriched with different dry dairy products up to 43 g kg(-1) protein content. The percentage of skimmed milk concentrate replaced with dry dairy products in the mix was between 1.37 and 6.35%. Yoghurts enriched with caseinates had higher viscosity and syneresis index (56.81 Pas and 548.8 g kg(-1) respectively) than yoghurts based on concentrated skimmed milk fortified with co-precipitate (39.00 Pas and 392.9 g kg(-1)) or blended dairy products (33.25 Pas and 431.8 g kg(-1)). One blended dairy product was tested to manufacture low-fat yoghurt on an industrial scale, yielding good rheological properties (high viscosity-consistence, 37.77 Pas, and low syneresis index, 450 g kg(-1)) and lower cost than traditional enrichment with skimmed milk powder. (C) 2000 Society of Chemical Industry.