Abstract:
To study the extraction of anthocyanins from Roselle Hibiscus sabddariffa L., anthocyanins stability in freeze dried powder and concentrated extract. A model system of a drink with added anthocyanin colorant was also studied. For anthocyanin extraction, it was found that a suitable solvent was water : ethanol (1:1), mixture adjusted of pH 2.5 by using hydrochloric acid. The ratio of roselle to solvent was 1:4. The effects of stabilizers (trehalose and maltodextrin at the concentration of 2 and 3% (w/v)) compared with control on anthocyanin stability through freeze drying effect were studied. The extract solution mixed with each stabilizer was freeze dried. The result showed that, after freeze drying, the percentage of anthocyanin retention and Degradation Index (DI) value of each treatment did not show a significant difference (p >0.05). After 15 weeks of storage, for all samples, the percentage of anthocyanin retention decreased. Considering the half-life of anthocyanins, the freeze dried anthocyanin colour with 3%(w/v) maltodextrin added showed the highest value at 578 days. To concentrate the extract solution, it was found that the most suitable condition was at 55 C, 30 min. The effects of stabilizers (glucose, sucrose, trehalose and maltodextrin at concentration of 2 and 3%(w/v)) compared with control were studied. The extract mixed with each stabilizer was concentrated. The results showed that the percentage of anthocyanin retention and DI value of each treatment did not show a significant difference (p >0.05). After 15 weeks of storage, for all samples, the percentage of anthocyanin retention decreased. Considering the half-life of anthocyanins, the concentrated anthocyanin colour with 3%(w/v) maltodextrin added showed the highest value at 86 days. A model system of a drink with added colorants (extract anthocyanin colour (0.1%w/v), SAN RED RC(R) (0.05%w/v) and synthetic carmoesin colour (0.05%w/v)) was studied. After 84 days of storage, the results showed that L*, triangleE* and hue angle values of drinks added extract anthocyanin colour and those added SAN RED RC(R) increased, while a* and chroma value decreased. However, those colour values showed no change in a drink with carmoesin added. The result obtained from sensory evaluation, the overall preference of a drink with extract anthocyanin colour was not acceptable after 56 days of storage, while the drinks with added either SAN RED RC(R) or carmoesin were acceptable through the peroid of 84 days storage.