The stability of beta-carotene under different laboratory conditions

The stability of β-carotene, the carotenoid with the highest vitamin A activity, has been investigated under laboratory conditions, other than food processing or food storage, β-Carotene appears to be fairly stable over 24 h (loss< 4%) and 48 h (loss < 15%) when micellar solutions in aqueous medium of this pigment were incubated at 37° C, in the dark, in a 5% CO2 in air atmosphere to simulate incubation conditions (used for cell culture systems). The effect of both UV light and fluorescent light on solutions of β-carotene in toluene was highly damaging (50% loss occurred after 8 h under UV light and after 24 h under daylight). Butylated hydroxytoluene (BHT) and alpha-tocopherol, two common antioxidants, were able to reduce significantly the degradation of β-carotene under light exposure. At the same concentration of BHT (1 mM), alpha-tocopherol had a much stronger relative potency to prevent the loss of the pigment (50% loss occurred after 48 h in fluorescent and 40 h in UV light in presence of alpha-tocopherol and after 23 h and 17 h, respectively, in fluorescent and UV light in presence of BHT). Increasing the rate of air-solution exchange by increasing the surface of β-carotene solution exposed to air caused an increase of the loss of the pigment of more than 3 times. Under storage conditions (-20° C, in the dark, under N2), the rate of loss of β-carotene was 1.5%/month and 1.1%/month, respectively, in absence or in presence of 0.025% BHT.