Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties

The fruit processing agroindustry generates waste, mainly composed of peels, which are often discarded but can be utilized as ingredients for developing new food products. However, their high perishability requires the application of preservation techniques, such as drying, which not only extends sh...

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Main Authors: Raniza de Oliveira Carvalho, Rossana Maria Feitosa de Figueirêdo, Alexandre José de Melo Queiroz, Francislaine Suelia dos Santos, Mailson Gonçalves Gregório, Lumara Tatiely Santos Amadeu, Henrique Valentim Moura, Nailton de Macedo Albuquerque Junior, Fabrícia Santos Andrade, Emily Bezerra Coutinho Cruz, Emerson Zambrano Lara, Josivanda Palmeira Gomes, Marta Suely Madruga
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Agriculture
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Online Access:https://www.mdpi.com/2077-0472/15/6/609
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author Raniza de Oliveira Carvalho
Rossana Maria Feitosa de Figueirêdo
Alexandre José de Melo Queiroz
Francislaine Suelia dos Santos
Mailson Gonçalves Gregório
Lumara Tatiely Santos Amadeu
Henrique Valentim Moura
Nailton de Macedo Albuquerque Junior
Fabrícia Santos Andrade
Emily Bezerra Coutinho Cruz
Emerson Zambrano Lara
Josivanda Palmeira Gomes
Marta Suely Madruga
author_facet Raniza de Oliveira Carvalho
Rossana Maria Feitosa de Figueirêdo
Alexandre José de Melo Queiroz
Francislaine Suelia dos Santos
Mailson Gonçalves Gregório
Lumara Tatiely Santos Amadeu
Henrique Valentim Moura
Nailton de Macedo Albuquerque Junior
Fabrícia Santos Andrade
Emily Bezerra Coutinho Cruz
Emerson Zambrano Lara
Josivanda Palmeira Gomes
Marta Suely Madruga
author_sort Raniza de Oliveira Carvalho
collection DOAJ
description The fruit processing agroindustry generates waste, mainly composed of peels, which are often discarded but can be utilized as ingredients for developing new food products. However, their high perishability requires the application of preservation techniques, such as drying, which not only extends shelf life but also adds value and enables their conversion into flour, expanding their applications. This study evaluated the convective drying of pineapple peels for flour production, analyzing bioactive, physical, and thermal properties. Moisture was reduced by 91%, reaching a hygroscopic equilibrium of 6.84%. The Two-Term model provided the best fit for the data, with an R<sup>2</sup> above 0.9997. Effective diffusivity increased with temperature, ranging from 2.83 × 10<sup>−10</sup> m<sup>2</sup>/s to 7.96 × 10<sup>−10</sup> m<sup>2</sup>/s, with an activation energy of 47.90 kJ/mol, as described by the Arrhenius equation. Thermodynamic properties indicated an endothermic, non-spontaneous process, with reductions in enthalpy (45.21; 45.04 kJ/mol) and entropy (−0.2797; −0.2802 kJ/mol·K) and an increase in Gibbs free energy (135.60–141.20 kJ/mol) at higher temperatures. Fresh peels contained high levels of bioactive compounds, such as phenolics (1740.90 mg GAE/100 g d.b.) and tannins (613.42 mg TAE/100 g d.b.), which were best preserved at 70 °C. Drying altered the physical properties of the flour, resulting in higher absolute, apparent and compact densities, lower porosity (75.81%), and a reduced angle of repose (21.22°) suggesting greater material stability. Thermal analysis identified five mass loss events related to the degradation of water, carbohydrates, proteins, and fibers. Differential scanning calorimetry confirmed the thermal stability of the treatments. Thus, the study highlights pineapple peels as a promising raw material for producing nutrient-rich functional flour, with a drying temperature being a crucial factor in preserving bioactive compounds and achieving desirable product characteristics.
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spelling doaj-art-f17dda37f1c4436eaad9a67bef5be44b2025-08-20T02:11:11ZengMDPI AGAgriculture2077-04722025-03-0115660910.3390/agriculture15060609Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal PropertiesRaniza de Oliveira Carvalho0Rossana Maria Feitosa de Figueirêdo1Alexandre José de Melo Queiroz2Francislaine Suelia dos Santos3Mailson Gonçalves Gregório4Lumara Tatiely Santos Amadeu5Henrique Valentim Moura6Nailton de Macedo Albuquerque Junior7Fabrícia Santos Andrade8Emily Bezerra Coutinho Cruz9Emerson Zambrano Lara10Josivanda Palmeira Gomes11Marta Suely Madruga12Department of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Agricultural Engineering, Federal University of Campina Grande, Campina Grande 58429-900, BrazilDepartment of Food Engineering, Federal University of Paraiba, João Pessoa 58051-900, BrazilThe fruit processing agroindustry generates waste, mainly composed of peels, which are often discarded but can be utilized as ingredients for developing new food products. However, their high perishability requires the application of preservation techniques, such as drying, which not only extends shelf life but also adds value and enables their conversion into flour, expanding their applications. This study evaluated the convective drying of pineapple peels for flour production, analyzing bioactive, physical, and thermal properties. Moisture was reduced by 91%, reaching a hygroscopic equilibrium of 6.84%. The Two-Term model provided the best fit for the data, with an R<sup>2</sup> above 0.9997. Effective diffusivity increased with temperature, ranging from 2.83 × 10<sup>−10</sup> m<sup>2</sup>/s to 7.96 × 10<sup>−10</sup> m<sup>2</sup>/s, with an activation energy of 47.90 kJ/mol, as described by the Arrhenius equation. Thermodynamic properties indicated an endothermic, non-spontaneous process, with reductions in enthalpy (45.21; 45.04 kJ/mol) and entropy (−0.2797; −0.2802 kJ/mol·K) and an increase in Gibbs free energy (135.60–141.20 kJ/mol) at higher temperatures. Fresh peels contained high levels of bioactive compounds, such as phenolics (1740.90 mg GAE/100 g d.b.) and tannins (613.42 mg TAE/100 g d.b.), which were best preserved at 70 °C. Drying altered the physical properties of the flour, resulting in higher absolute, apparent and compact densities, lower porosity (75.81%), and a reduced angle of repose (21.22°) suggesting greater material stability. Thermal analysis identified five mass loss events related to the degradation of water, carbohydrates, proteins, and fibers. Differential scanning calorimetry confirmed the thermal stability of the treatments. Thus, the study highlights pineapple peels as a promising raw material for producing nutrient-rich functional flour, with a drying temperature being a crucial factor in preserving bioactive compounds and achieving desirable product characteristics.https://www.mdpi.com/2077-0472/15/6/609phenolic compoundseffective diffusivitypineapplecalorimetryFTIR
spellingShingle Raniza de Oliveira Carvalho
Rossana Maria Feitosa de Figueirêdo
Alexandre José de Melo Queiroz
Francislaine Suelia dos Santos
Mailson Gonçalves Gregório
Lumara Tatiely Santos Amadeu
Henrique Valentim Moura
Nailton de Macedo Albuquerque Junior
Fabrícia Santos Andrade
Emily Bezerra Coutinho Cruz
Emerson Zambrano Lara
Josivanda Palmeira Gomes
Marta Suely Madruga
Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
Agriculture
phenolic compounds
effective diffusivity
pineapple
calorimetry
FTIR
title Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
title_full Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
title_fullStr Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
title_full_unstemmed Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
title_short Dynamic Modeling of Convective Drying of Pineapple Peels: Bioactive, Physical, and Thermal Properties
title_sort dynamic modeling of convective drying of pineapple peels bioactive physical and thermal properties
topic phenolic compounds
effective diffusivity
pineapple
calorimetry
FTIR
url https://www.mdpi.com/2077-0472/15/6/609
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