Golden beet (Beta vulgaris var. lutea) color was found to contain 8 components, of which the most important seemed to be vulgaxanthin-I and -II. Purified vulgazanthin -I solutions are easily degraded at high temperatures. The stability is, however, strongly dependent on pH: the stability is best at pH values between 5 and 6, the poorest at low pH values, but at pH 7 the stability is better than that of betanin. Vulgaxanthin-I is more stable in the raw extract than in a purified solution. EDTA, even in ppm amounts, was found to improve the stability of betanin. The effect was dependent on pH value, being most efficient at pH 2.0 and 5.0. Stability of vulgaxanthin-I was not improved by EDTA. Tannin did not show stabilizing influence. Ascorbic acid was found to have an unfavorable influence on stability, especially in the case of betanin.

The relationship between the malonaldehyde formed as oxidation product of lipids, and changes of proteins in frozen Baltic herring (Clupea harengus var. membranus) was studied. Changes occurred in the muscle proteins due to freezing, so that water-binding capacity, solubility, and the amount of free epsilon-amino groups in these proteins decreased. A close relationship was found between the amount of malonaldehyde and changes of proteins in the different phases of storage. The reaction of malonaldehyde with the free amino groups of the proteins may be one of the factors on which the changes of proteins during frozen storage are based.

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The stability of vulgaxanthin I at 100 degrees C is dependant on the water activity of the system. The half-life of vulgaxanthin I was found to be three times greater at aw 0.20 than at 1.00. The rate constants for vulgaxanthin I degradation varied exponentially with respect to water activity and below aw = 0.50 the stability was not improved.