Hysteresis and thermodynamic properties of water sorption in ‘Malagueta’ pepper seeds

Silva, Ênio Farias de França e; Rodovalho, Renato Souza; Silva, Isneider L.

doi:10.1590/1807-1929/agriambi.v22n9p658-663

Cited by 4 publications

(1 citation statement)

References 25 publications

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“…Sorption hysteresis refers to the difference in the moisture content of material between adsorption and desorption isotherms at the same RH (Wolf et al, 1972;Yang et al, 1997); more water is held within desorbing seeds than within adsorbing seeds between upper and lower closure points where the isotherms come together again (Ellis et al, 1989;Bell and Labuza, 2000;Silva et al, 2018). Hence, most of the hysteresis effect occurs in region II of the isotherm (Roberts and Ellis, 1989).…”

Section: Introductionmentioning

confidence: 99%

Contrasting seed moisture sorption behaviour between two species and the implication for seed longevity

2023

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Understanding seed moisture desorption and adsorption isotherms is important for seed quality maintenance and better predicting seed storage lifespan. Freshly harvested oilseed rape and barley seeds were dried and then rehydrated twice. Seed equilibrium relative humidity (eRH) and moisture content (MC) were determined at different humidity levels so that two cycles of desorption and adsorption could be constructed. In addition, seeds were dried to 30% RH and then rehydrated to 50% RH for five cycles to determine whether they shift to the adsorption isotherm. Monolayer MC was determined using the Gugenheim-Anderson-de Boer model. Storage experiments were conducted for seeds equilibrated at 30, 40, 50, 60 and 70% RH for two cycles of desorption and adsorption at 45°C. Isotherm curves’ shapes were similar for oilseed rape and barley, although spanning a greater MC range in barley. The hysteresis effect was observed for oilseed rape and barley seeds when dried over silica gel at <10% RH. However, this effect was only observed for barley seeds when dried to 30% RH, but not for oilseed rape seeds. Longevity was greater for adsorbing seeds than desorbing seeds at a given eRH, however, there was no significant difference in σ (the standard deviation of the normal distribution of seed deaths over time)–MC log–log relationship. The relationship shifted for seeds on the second cycle. In conclusion, if seed lots are stored at a specific RH, reaching equilibrium by desorption or adsorption can strongly influence their longevity. Also, when seeds of different species are dried to low RH, they will respond differently to a subsequent increase in RH, which could profoundly affect their longevity.

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Section: Introductionmentioning

confidence: 99%

Contrasting seed moisture sorption behaviour between two species and the implication for seed longevity

2023

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Seed responses to change in ambient humidity and the consequences for storability

Rezaei,

Buitink,

Hay

2024

Journal of Stored Products Research

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Desorption isotherms and thermodynamic properties of Solanum gilo

et al. 2020

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Solanum gilo is a plant belonging to the family Solanaceae with a probable origin in Africa. It was introduced to Brazil by workers. The fruit is cultivated by small producers in Brazil and it is a source of food for the low-income population. Its seeds are harvested with high moisture contents, and the drying process is necessary. Sorption isotherms consist of the relation between water activity (aw) and moisture content of an agricultural product at a constant temperature. This information contributes to the drying process, thus favoring an increased longevity of agricultural products, such as seeds. This research aims to determine the desorption isotherms of Solanum gilo seeds and calculate their thermodynamic properties (enthalpy, entropy and Gibbs free energy). Sorption experiments were performed by the gravimetric static method using saline solutions. Several mathematical models were fitted to the experimental data, and the selection of the best model was performed by statistical criteria. Equilibrium moisture contents were obtained at 10, 20 and 30°C and at water activities between 0.111 and 0.985 (decimal). The modified Oswin model best represents moisture desorption isotherms of Solanum gilo seeds under the studied conditions. The energy required for the process was 0.22-555.68 kJ kg-1. The latent heat of vaporization (L), the enthalpy (Qst), the entropy (ΔS) and the Gibbs free energy (ΔG) increased with the reduction of the equilibrium moisture content of seeds. The theory of isokinetics is valid for the desorption process.

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Hysteresis and thermodynamic properties of water sorption in ‘Malagueta’ pepper seeds

Cited by 4 publications

References 25 publications

Contrasting seed moisture sorption behaviour between two species and the implication for seed longevity

Contrasting seed moisture sorption behaviour between two species and the implication for seed longevity

Seed responses to change in ambient humidity and the consequences for storability

Desorption isotherms and thermodynamic properties of Solanum gilo

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