Radiation Preservation of Milk and Milk Products. III. The Thiobarbituric Acid Test as a Means of Evaluating Radiation-Induced Changes in Milk

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Abstract
The thiobarbituric acid test was useful as an index of degree of radiosensitivity of milk. Values of optical density at the main absorption maximum at 500 mu exhibited a linear function with respect to dose. The values are believed to express relative amounts of milk degradation, in fair agreement with results obtained by measurement of browning reaction. Chromatographic separation showed that several groups of pigments were formed. The red pigment, absorbing at 535 m[mu] was produced by all milk components investigated. The components produced by irradiation of emulsified milk fat and fat free milk residue were apparently similar. Pigments absorbing at 500 mu and a heterogenous group of yellow pigments were produced by irradiation of all milk components except those from purified fats. The simplest components producing pigments absorbing under similar conditions of irradiation were glycerol and ethylene glycol.