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Advisor(s)
Abstract(s)
Watercress (Nasturtium officinale) is one of the most popular leafy vegetables consumed in the world,
either fresh or cooked, presenting high contents of phytochemicals and bioactive compounds. However,
due to its high moisture content (91% w.b.), this vegetable is easily perishable. To prolong shelf life and
provide the convenient transportation, dried watercress might be a novel product for consumption in soups
and other recipes. Convective air drying is an affordable process, but may cause significant nutritional
degradation in vegetables, given their sensitivity to heat, light, oxygen and leaching phenomena. Therefore,
the purpose of this study was to evaluate the drying characteristics and the effects of drying temperature
on quality attributes of watercress, without any pre-treatments.
Drying at temperatures of 40, 55 and 70 ⁰C resulted in drying times of 230, 119 and 92 minutes,
respectively. The nutritional parameters were negatively correlated with the drying temperature.
Retentions of 12.5±3.8 - 72.8±4.2%, 51.1±3.3 - 80.4±4.8%, and 44.3±6.1 - 92.1±12.2% were obtained for
vitamin C, total phenolic compounds and total antioxidant activity, respectively. Increased values of total
colour difference (TCD), browning index (BI) and higher chlorophylls losses (26.1±3.9-55.6±14.9%) were also
observed as drying temperature increased.
In conclusion, convective air drying affected considerably both watercress’s nutritional values and quality
characteristics. Moreover, more pronounced deterioration was observed when higher drying temperatures
were employed. Alternative drying methods or application of pre-treatments prior to drying are suggested
for further research on dehydrated watercress, which is expected to be a novel product for food recipes or
as a food supplement powder.
Description
Keywords
Watercress Convective air-drying Colour Nutritional quality
Pedagogical Context
Citation
PICHMONY, E. K.; ARAÚJO, Ana C.; OLIVEIRA, Sara M.; RAMOS, Inês N.; BRANDÃO, Teresa R. S.; SILVA, Cristina L. M. - Effects of convective air drying temperature on nutritional quality and colour of watercress (Nasturtium officinale). In 29th EFFoST Conference - Food Science Research and Innovation: Delivering Sustainable Solutions to the Global Economy and Society, Athens, Greece, 10-12 November 2015. – In DERMESONLOUOGLOU, Efimia …[et al.] (ed.) - Proceedings 29th EFFoST Conference. Athens: NTUA, School of Chemical Engineering, 2015. ISBN 978-618-82196-1-8. Vol. 2, p. 834-839