Effect of sulphur dioxide and blanching on the stability of carotenoids of dehydrated carrot

The influence of blanching and sulphiting of carrot on the stability of carotenoids of dehydrated carrot was evaluated. The carotenoid content of untreated and treated carrots was measured after dehydration and during storage of dehydrated carrot at 37°C. Sulphiting was found to have a marked effect on the stability of carotenoids of both unblanched and blanched carrots during dehydration and storage at 37°C. The effectiveness of sulphur dioxide was reduced by increasing blanching time to over 1 min, the period in which the carrot becomes just adequately blanched. Even 9621 μg −1 SO 2 in over‐blanched carrot was not as effective as less than one‐quarter of this concentration in carrot that had been just adequately blanched. The combination of sulphiting, and blanching to a level sufficient to inactivate peroxidase activity, is considered to be the most effective method for enhancing the storage life of the product, and optimisation of the blanching process is highly desirable in order to gain the maximum benefit from the SO 2 treatment.