Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Food Science and Industries


Carl Anton Ernstrom


Residual rennin in cheese whey and curd was measured by using a special sensitive substrate. The substrate was made by reconstituting 6 g NDM in 500 ml of buffer containing 0.2 M CaCl2, 0.5 M cacodylic acid and 0.2 M triethanolamine at pH 5.7. Cheese curd was blended into a 1:7 slurry (1 part curd, 7 parts water), and 1.67% sodium chloride was added to the why and slurry to liberate residual rennin from casein. The residual rennin in cheese whey and slurry were determined simultaneously with an identical sample containing known rennin activity. Samples with known activity were prepared by destroying the residual rennin in unknown samples after which a known amount of rennin was added back to a standard. The examine the effectiveness of this method for measuring rennin activity in whey or slurry, a recovery test was developed to measure rennin activities in the whey and curd made by centrifuging rennet-coagulated milk. The average total recovery from 15 replications was 101.6 ± 2.4%. It was found that pH was a main factor affecting rennin distribution between whey and curd. The amount in the curd increased with decreasing pH at setting. Adding 0.02% CaCl2 to milk was of little effect.

The results showed that 68.1 6 ± 6.6% of the residual rennin was found in Cheddar cheese whey after dipping and 17.2 6 ± 2.6% of the residual rennin was in the curd after milling.