Study on biological value changes of Latvian wild cranberries during convective drying
2012
Dorofejeva, K. | Rakcejeva, T.
Drying is the main processing possibility for the prolonging of cranberries shelf life. Convective drying with a controlled hot air circulation is the most typical drying process. The main aim of the current research was to investigate the changes of biologically active components in wild cranberries during convective drying. During the experiments berries were cut prior to drying and dried in a chamber with a controlled hot air circulation at various temperatures: +30-+90°C with the interval of +10°C. Cranberries were dried till constant moisture content 9.0±0.1% for storage. Changes of colour (using the colour system CIE L*a*b*), carotenoid and anthocyanins (spectrophotometric), and vitamin C content (HPLC) were evaluated by means of the standard methods. The temperature not higher than +50±2°C (the drying time 20 h and 20 min) could be acceptable as the optimal drying parameters of cranberries, since the increase of the processing temperature by more than +50±2°C results in a relevant decrease of vitamin C content. As the results of our experiments show the value of darkness (L*) increases 1.6 times and the intensity of red colour (a*) decreases 1.3 times during drying of cranberries; thus indicating on the decrease of the content of anthocyanins in berries. However, the content of carotenoid was not changed significantly (0.053-0.057 mg 100 g-1 in dry matter).
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