Date of Award:

5-1987

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Committee Chair(s)

Carl Anthon Ernstrom

Committee

Carl Anthon Ernstrom

Committee

R. J. Brown

Committee

R. L. Olsen

Committee

D. V. Sisson

Abstract

Pasteurized skimmilk at 4°C was acidified to pH 5.8 with 85.5% phosphoric acid (136g H3PO4/100 kg skimmilk), then warmed to 54°C and ultrafiltered to a protein concentration 9.1 ± 0.2%. The retentate was heated to 76.5°C for 16 s then cooled to 2°C. Phosphoric acid (85.5%) was added at a rate of 3.41g per kg retentate. The acidified retentate was slowly warmed to 29.5°C (3°C/5 min) when the pH was checked. The pH at this point was no lower than 5.4. Heating was continued until a temperature of 32.2°C was reached. Glucono delta lactone was added to the retentate (17.6 g/kg retentate) and left undisturbed for approximately 80 min. The curd was cut at pH 4.7 with 0.64 cm curd knives and allowed 10 min for syneresis. Permeate obtained from the same lot of milk was acidified to pH 4.8 (66 g H3PO4/100 kg permeate), then added to the curd at 32.2°C (three parts permeate to four parts retentate) and used as a cooking vehicle. The curd was cooked to 59°C in 90 min. The curd was held at 59°C for 10 min, drained and washed once with ice water. Cream dressing containing 12.5% fat and 3% salt was used at the rate of two parts curd to one part dressing.

Control cottage cheese was produced by a direct acid method from the same skimmilk used to produce ultrafiltered curd.

Use of ultrafiltered skimmilk retentate for cottage cheese making resulted in 2.24% more curd (corrected to 20% solids) and 2.24% more curd per kg original milk protein than the control. However, satisfactory firmness in UF curd required slightly more than 20% solids in the final product. Sensory evaluations indicated that creamed cottage cheese was not significantly different (p < 0.05) from control cheese, but was better than commercial cottage cheese samples selected from the local market.

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