COLOR STABILITY OF BETANIN

Some chemical and physical factors were evaluated for their effects on stability of betanin in model systems and in beet juice. Results indicate that the stability of betanin color is pH sensitive and generally is less than that of artificial dyes. The color of betanin is most stable between pH 4.0 and 6.0. Thermostability of betanin was pH dependent and was greatest between pH 4.0 and 5.0. The half‐life of betanin at pH 5.0 and 100°C was 14.5 min, and increased in an unprotected model system to 1150 min at 25°C. The rate at which betanin degraded in model systems was affected by air and/or light. The cumulative effect of these two conditions was a reduction in the half‐life of betanin by 28.6%. The half‐life of betanin in beet juice at pH 5.0 was greater than in model systems. Despite limited stability of betanin in model systems, there are many foods in which betanin could be used as a colorant. Foods to be colored with betanin should have a pH between 4.0 and 7.0, be exposed to low temperatures and be protected from air and/or light to achieve maximum color stability.