FERMENTATION OF CONCENTRATED SKIM-MILK - EFFECTS OF DIFFERENT PROTEINLACTOSE RATIOS OBTAINED BY ULTRAFILTRATION-DIAFILTRATION/

Defatted milk was ultrafiltered-diafiltered in a 20 kDa polysulphone F rat membranes UF unit to obtain concentrated milk with different prote in/lactose ratios. Different samples of concentrated-diafiltrated milk s with protein concentration between 4.7% and 8.9% and lactose concent ration between 2.7 and 0.8% (protein/lactose ratios between 1.7 and 9. 5) were fermented (Lactobacillus bulgaricus and Streptococcus thermoph ilus) to obtain yoghurt-like products. Firmness of the coagulum as wel l as pH, colony count and organoleptic test were considered in the fin al products. Concentrated-diafiltrated milk with lactose and protein c ontents lower than 2% and 6.5%, respectively, lead to a very liquid pr oduct. Enriched protein low-lactose fermented milks can be obtained by this technology. (C) 1998 SCI.