Drying Accelerators to Enhance Processing and Properties: Ethanol, Isopropanol, Acetone and Acetic Acid as Pre-treatment
- PDF / 2,990,698 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 49 Downloads / 185 Views
ORIGINAL RESEARCH
Drying Accelerators to Enhance Processing and Properties: Ethanol, Isopropanol, Acetone and Acetic Acid as Pre-treatments to Convective Drying of Pumpkin Gisandro Reis Carvalho 1
&
Meliza Lindsay Rojas 2
&
Isabela Silveira 1
&
Pedro Esteves Duarte Augusto 1,3
Received: 8 July 2020 / Accepted: 8 October 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Different drying accelerators were studied to improve vegetable drying: acetone (AC), ethanol (ET), isopropanol (ISO) and acetic acid (AA). Pre-treatments were performed by immersion of pumpkin cylinders. Convective drying was performed at 40 °C and air velocity 1 m/s. Different aspects were evaluated: drying kinetics, structural changes (microstructure and macrostructure), thermal profile and viscoelastic and rehydration behaviours. The microstructure was modified by pre-treatments, being more pronounced with AC and AA. Thinner cell walls, changes on turgor and extraction of components and air were reported, affecting the mass transfer. Moreover, the microstructural changes reinforced anisotropy and also affected the macrostructure, changing the viscoelastic behaviour. All pre-treatments resulted in a super-diffusive behaviour, decreasing the drying time from 9% (ISO) to 22% (AC). Possible relations were discussed among the compounds’ physical properties, sample temperature profile, drying kinetics and equilibrium moisture. Rehydration was improved by ET and ISO, but impaired by AA. Although AC accelerates drying, it did not affect the rehydration. The viscoelasticity reflected the structure and composition, with the pre-treatments with higher structure modifications (AA and AC) losing elastic properties. In conclusion, the pre-treatments with isopropanol and ethanol showed better results, improving drying and rehydration, and are thus recommended. Keywords Drying kinetics . Convective drying . Food properties . Viscoelasticity . Structure
Highlights • Drying accelerators were evaluated to enhance the process and the properties of pumpkin. • Pre-treatments promoted structural changes in the product, reflecting on stress-relaxation behaviour. • The structural changes modified drying and rehydration. • Drying time was reduced from 9 to 22% depending on the compound used. • Ethanol and isopropanol accelerated rehydration and increased the absorbed water. Gisandro Reis Carvalho and Meliza Lindsay Rojas are joint first authors and equally contributed to this work. * Gisandro Reis Carvalho [email protected] 1
Department of Agri-food Industry, Food and Nutrition (LAN), Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo (USP), Av. Pádua Dias, 11, Agronomia, Piracicaba, SP 13418-900, Brazil
2
Dirección de Investigación y Desarrollo, Universidad Privada del Norte (UPN), Trujillo, Peru
3
Food and Nutrition Research Center (NAPAN), University of São Paulo (USP), São Paulo, Brazil
Food Bioprocess Technol
Introduction Drying is an important unit operation widely used to produce stable
Data Loading...
