Influence of drying by convective air dryer or power ultrasound on the vitamin C and β-carotene content of carrots.
Convective air drying and power ultrasound effects on vitamin C and β-carotene contents in carrots were studied. For convective air drying, a central composite face-centered design fitting temperature between 40 and 65 °C and air flow rate between 2 and 6 × 10(-1) m/s were used; previously, carrots were blanched. Likewise, ultrasound drying was performed on both unblanched and blanched carrots at 20, 40, and 60 °C for 120, 90, and 75 min, respectively. Blanching had a sharp effect on vitamin C and β-carotene degradation (80-92% retentions, respectively), and convective air drying led to further losses (32-50% and 73-90% retentions, respectively). According to the response surface model, a combination of 40 °C and 6 × 10(-1) m/s will maximize vitamin C retention in dried carrots, whereas 40 °C and 3.3 × 10(-1) m/s will ensure the highest β-carotene content. Ultrasound drying caused higher vitamin C and β-carotene retention (82-92% and 96-98%, respectively) than convective air drying. Blanched carrots dehydrated by ultrasound showed retentions of 55% and 88% of vitamin C and β-carotene, respectively. Ultrasound drying at 20 °C for 120 min caused the maximum vitamin C and β-carotene contents. Therefore, power ultrasound may be considered a valuable tool to obtain high nutritive dehydrated carrots.
Frias
Juana
J
Instituto de Ciencia y Tecnología de Alimentos y Nutrición CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
Peñas
Elena
E
Ullate
Mónica
M
Vidal-Valverde
Concepción
C
D001205:Ascorbic Acid / Q000032:analysis*; D018481:Convection; D018552:Daucus carota / Q000737:chemistry*; D003890:Desiccation / Q000379:methods*; D009753:Nutritive Value; D014465:Ultrasonics; D019207:beta Carotene / Q000032:analysis*
D019207:beta Carotene; D001205:Ascorbic Acid