The effect of fluorescent light on the degradation rates of betanine and the major cranberry anthocyanins was determined in model systems. Degradation rates were measured in the presence of oxygen in a temperature range 25-55°C. Retained pigment was separated and quantified by high performance liquid chromatography. Light had a minimal effect at 55°C because of considerable thermal destruction. However, at 40°C for anthocyanins and 25°C for betanine, light was responsible for most of the degradation occurring. Light increased rates of anthocyanin degradation more than those of betanine. Molecular oxygen was necessary for light to have a significant effect.

This research was supported by the Illinois Agricultural Experiment Station, University of Illinois, and a grant from the Illinois Soybean Program Operating Board.

Effects of a wide variety of antioxidants and related compounds on the stability of betanine were measured in air-saturated solutions at 40°C pH 5.0. No phenolic or sulfur-containing antioxidant was effective in stabilizing the pigment. Ascorbic and isoascorbic acids had similar effects in improving betanine stability in a citrate buffer. When citric acid was combined with ascorbic acid, the antioxidant effect was no greater than when ascorbic acid was used alone.

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