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USE OF SEMI‐AUTOMATIC INSTRUMENTS FOR PROCESS AND PRODUCT CONTROL IN THE DAIRY‐FOOD INDUSTRY
Author(s) -
MCGANN T. C. A.,
O'CONNELL J. A.,
MCFEELY ROSARIO
Publication year - 1975
Publication title -
international journal of dairy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.061
H-Index - 53
eISSN - 1471-0307
pISSN - 1364-727X
DOI - 10.1111/j.1471-0307.1975.tb00360.x
Subject(s) - kjeldahl method , chemistry , skimmed milk , dairy industry , whey protein , chromatography , acetic acid , food science , food industry , biochemistry , organic chemistry , nitrogen
An integrated procedure for the rapid determination of total protein and heat treatment classification of skim milk powders by dye binding is described. Total protein values estimated by the Pro‐Milk were in good agreement with the macro‐Kjeldahl method; the correlation coefficient was +0–98 and the SD of the differences between the two methods was ±0.55, corresponding to a CV of ±1.52 per cent. Residual undenatured whey protein was measured by the Pro‐Milk difference (PMD) method on undiluted isoelectric filtrates. These were prepared by addition of acetic acid ‐ sodium acetate buffer to reconstituted skim milk powders. The undenatured whey protein levels thus determined correlated well with the ADMI Kjeldahl procedure. The reproducibility of the PMD method in our laboratory was ±0.010, and satisfactory reports on the reliability of the Pro‐Milk procedure have been received from industry. It is recommended that future heat treatment classifications of milk powders should be based on dye binding. Furthermore, it is proposed that milk powders should be heat classified according to the percentage of undenatured whey protein to total protein in the reconstituted milk and expressed as the whey protein ratio (WPR) of the milk powder.