Proteolysis detection in milk. IV. Starch-gel electrophoresis and formol titration.
Starch-gel electrophoresis (SGE) and formol titration methods for detecting proteolysis in cold-stored raw milk have been studied to establish their value as quality indices. When examined by SGE, the first evidence of proteolysis in raw milks stored at 5 degrees C was the formation of para-k-casein. However, this fraction could not be detected on the starch gels until the total bacterial count (TBC) exceeded 10-minus 7/ml. The SGE method appeared more reliable than the previously discussed tyrosine value method. Formol titration did not appear to have any application in the screening of cold-stored raw milks with TBC less than 10-minus 7/ml, but would detect some milks of poorer bacteriological quality.
D000818:Animals; D002364:Caseins / Q000032:analysis; D002452:Cell Count; D004592:Electrophoresis, Starch Gel; D005069:Evaluation Studies as Topic; D005519:Food Preservation; D005557:Formaldehyde; D008892:Milk / Q000382:microbiology / Q000592:standards; D008894:Milk Proteins / Q000378:metabolism*; D011551:Pseudomonas fluorescens; D013696:Temperature; D013997:Time Factors; D014443:Tyrosine / Q000032:analysis
D002364:Caseins; D008894:Milk Proteins; D005557:Formaldehyde; D014443:Tyrosine