Biomedical subjects

G K Murthy

Publications and source records attributed to G K Murthy.

At least 19 recordsLinked to original sources

PubMed1981

Determination of alkaline phosphatase in casein: collaborative study.

A collaborative study was made to determine alkaline phosphatase in casein samples by the rapid colorimetric test. Six to eight collaborators tested 10 unknown casein samples containing various amounts of residual phosphatase with and without the addition of magnesium acetate. Results indicated that magnesium acetate significantly increased phosphatase activity. The collaborators correctly analyzed 95% of the samples with the added magnesium acetate. The method has been adopted official first action.

Alkaline Phosphatase↗

PubMed1979

Rapid methods for differentiating reactivated from residual phosphatase in milk and cream: collaborative study.

Three methods for differentiating reactivated from residual phosphatase in milk and cream were collaboratively tested using both magnesium acetate and magnesium chloride for reactivating phosphatase. The methods evaluated were the modified Scharer rapid test, the rapid colorimetric test, and the Rutgers method. Nine collaborators tested 6 unknown milk samples containing reactivated and/or residual phosphatase, and 16 collaborators tested 6 unknown cream samples containing reactivated and/or residual phosphatase. Results indicated that use of magnesium acetate in place of magnesium chloride for reactivating phosphatase improved test results. Visual tests (modified Scharer rapid and Rutgers) predicted correct results when the samples contained high levels of reactivated or residual phosphatase. In borderline cases where the reactivated phosphatase contents of the undiluted control sample and the diluted sample containing Mg were very close, the test results of the visual methods were significantly different from 100% correct results at the alpha=0.05 level. Use of a photoelectric colorimeter or its equivalent for measuring the absorbance in conjunction with the modified Scharer rapid test improved results considerably. The modified Scharer rapid test was adopted official first action.

Acetates↗

PubMed1976

Reactivation of alkaline phosphatase in ultra high-temperature, short-time processed liquid milk products.

Alkaline phosphatase (enzyme) reactivation was studied in liquid milk products heated to 87.8 to 121.1 C for less than 1 s in a continuous, two-phase, slug-flow heat exchanger. The effects of magnesium concentration, pH, incubation temperature, homogenization pressure, processing temperature, fat content, and initial enzyme concentration were investigated. Jersey milk from one farm showed seasonal variations in enzyme concentration and its reactivation behavior. Increased reactivation in products with high fat content was due to high initial enzyme concentration in the product. Homogenization of products before heating decreased reactivation. Maximum reactivation occurred in products heated to 104.4 C, incubated at 34 C, and adjusted to pH 6.5. Maximum velocity of reactivation and reactivation constant varied with milk samples. Activation energy for the control and samples with magnesium was 22.646 +/- .118 and 24.100 +/- .210 kJ mole-1, respectively. The enzyme from raw and reactivated cream contained two major isozymes, and the reactivated isozyme differed from the control. The official method for differentiating residual and reactivated enzymes was modified in terms of magnesium concentration and extent of reactivation of the enzyme in the reactivated product.

Alkaline Phosphatase↗

PubMed1972