Cottage Cheese From Ultrafiltered Skim Milk

Ultrafiltration of skim milk was conducted at 4.4, 21.0 and 49.0°C to provide retentates for cottage cheese trials. Fractionation at 21.0 and 49.0°C improved initial permeation flux rate (PR) by 50 and 300%, respectively, over that observed at 4.4°C. Rates of decline of PR de creased with increasing temperature. Retentate ratios of undenatured whey protein nitrogen:casein nitrogen (CN) and proteosepeptone:CN were unchanged during ultrafiltration whereas nonprotein nitrogen:CN declined at each temperature. Calcium concentration of permeate was 1–2% less at 49.0 than 4.4°C because of increased calcium concentration of retentate at higher temperature. Large curd, creamed cottage cheese was prepared successfully from each retentate, cooking temperature and/or time being reduced because of initially firmer curd. Intermediate temperature (21.0°C) processing induced rapid microbial proliferation after > 2 hr. The utility of ultrafiltration as a preconcentration step for continuous cottage cheese production is discussed.