The convective drying of yacon was investigated (40-70 C). Pulsed vacuum osmotic dehydration (PVOD) (sorbitol 38 Brix, 35 C, 681 mmHg in the first 10 min) as pretreatment was tested. Drying behavior, energy consumption, diffusivity, fructooligosaccharide (FOS) retention, shrinkage, water activity, shrinkage, and color were measured. Fick's model was adequate for drying kinetics adjustment, mainly for untreated samples with shrinkage consideration. PVOD pretreated dried yacon was a less shrunken product in a shorter drying time with up to 60% FOS retention. Nevertheless, the best tested condition for FOS retention (88%) was the convective drying at 60 C without PVOD application.
Practical ApplicationsThe yacon is a seasonal plant that presents high concentrations of functional compounds. Like most vegetables, its shelf life is short and storage difficult. Therefore, improved techniques for conservation are required. The present paper evaluates the effects of drying temperature on the production of fresh and osmodehydrated yacon slices during convective drying. This study could offer an interesting response to the changes promoted by these processes, relating to the modifications to the physicochemical properties of osmodehydrated yacon.
| INTRODUCTIONThe yacon (Smallanthus sonchifolius) is a tuberous plant belonging to the family Asteraceae and from the Andean region, where it is mainly cultivated and consumed (Kamp, Hartung, Mast, & Graeff-Hönninger, 2019). It is also cultivated in Japan, Brazil, Czech Republic, New Zealand, Italy, and Germany (Ojansivu, Ferreira, & Salminen, 2011). The root of its 2.0-2.5 m herbaceous plant is a prebiotic food with high content of fructooligosaccharides (FOS) and a short shelf life (Delgado, da Silva Cunha Tamashiro, Mar ostica Junior, & Pastore, 2013).The yacon root presents a relatively sweet taste, and a crispy and juicy texture, being mainly consumed in its fresh form (Reis, Marques, de Moraes, & Masson, 2021). It was reported that after postharvest, the FOS content in yacon is hydrolyzed into reducing sugars (Delgado et al., 2013).Drying could be an interesting process for the availability of products with high contents of nutritional components in an off season period (Corrêa et al., in press). The convective drying is the most common drying technique and was previously studied for yacon roots by