Provitamin A carotenoids and ascorbic acid contents of the different types of orange juices marketed in Spain

The vitamin C and provitamin A carotenoids contents of 25 commercially available Spanish orange juices were studied. Large differences in the levels of these compounds were found. On average, ultrafrozen orange juices (UFOJ) and orange juices from the ecological agriculture (OJFEA) showed the highest ascorbic acid contents (518 and 412 mg/l respectively) among the different kinds of orange juices studied. Some disagreement between the declared and the actual amounts of vitamin C were found. Provitamin A carotenoids were determined by means of the corresponding standards. The monohydroxycarotenoid accompanying β-cyptoxanthin in orange juices was identified as the non-provitamin A carotenoid, zeinoxanthin, on the basis of the methylation test with acidified methanol. Unusually high contents of β-carotene (>0.5 mg/l) were found in two samples, which could indicate that substantial amounts of the pigment were added to those juices. The mandarin juice analyzed showed the highest provitamin A activity (359.3 retinol activity equivalents/l) Among the orange juices surveyed, UFO proved to be the best source of provitamin A (78.5 retinol activity equivalents/l, on average). The lowest contents were found in orange juices from concentrate (OJFC) (22.4 retinol activity equivalents/l, on average, without considering the orange juices with unusual β-carotene contents).