Convective, vacuum and microwave drying kinetics of mallow leaves and comparison of color and ascorbic acid values of three drying methods


FOOD SCIENCE AND TECHNOLOGY, vol.34, no.2, pp.358-364, 2014 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 34 Issue: 2
  • Publication Date: 2014
  • Doi Number: 10.1590/s0101-20612014005000033
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.358-364
  • Keywords: ascorbic acid, convective drying, color, mallow, microwave drying, vacuum drying, OSMOTIC DEHYDRATION, SYSTEM, DRYER
  • Bursa Uludag University Affiliated: Yes


Mallow leaves (Malva sylvestris L.) with initial moisture of 5.02 +/- 0.003 on dry basis (82.5% on wet basis) were dried using three different drying methods, microwave, convective and vacuum. The leaves that weigh 75 g each were dried until their moisture fell down to 0.10 +/- 0.005 on dry basis (approximately 9% on wet basis). The following drying levels were used in each of the drying processes: 6.67, 8.67, 10, 11.33 W g(-1) microwave power density; 50, 75, 100 and 125 degrees C for convective drying; and 3, 7 kPa at 50 and 75 degrees C for vacuum drying. Drying periods ranged from 6-10, 26-150 and 38-130 min. for microwave, convective and vacuum drying, respectively. Effective moisture diffisuvities ranged from 2.04403 10(-10)-3.63996 10(-12) m(2) s(-1), 1.70182 10(-11)-1.10084 10(-10) m(2) s(-1) and 1.85599 10(-11)-5.94559 10(-10) m(2) s(-1) for microwave, convective and vacuum drying, respectively. According to ascorbic acid content and color parameters, the best microwave power density was found 10 W g(-1) with a drying period of 6.5 min.