Moisture sorption characteristics of microalgae Spirulina platensis

Oliveira, E.G.; Rosa, Gabriela Silveira da; Moraes, Mariana Agostini de; Pinto, Luiz Antônio de Almeida

doi:10.1590/s0104-66322009000100018

Cited by 19 publications

(7 citation statements)

References 25 publications

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“…The results of the desorption isotherms of the olive leaves are presented in Figure 2, where can be verified that the curves showed a sigmoidal behavior and, according to Brunauer et al (1940), these curves could be classified as type II isotherms. Similar results were observed for the olive leaves by Bahloul et al (2008) and microalgae Spirulina platensis by Oliveira et al (2009). Table 2 shows the parameters of the mathematical models (Equations 1 to 3) adjusted to the experimental data, as well as the values of P and R 2 .…”

Section: Resultssupporting

confidence: 70%

Effects of different drying conditions on bioactive potential of Brazilian olive leaf

Cagliari

Martiny

Nascimento

et al. 2022

Braz. J. Food Technol.

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Olive leaf is a residue in olive oil and fruits production, which is considered with bioactive potential due to the high antioxidant activity attributed mainly to the phenolic compounds. The research aimed to investigate the Brazilian olive leaf drying, and also study its influence on the bioactive potential of the leaf. The desorption isotherms of olive leaves were determined and experimental curves were fitted to GAB, BET and Peleg models. Convective drying in a fixed bed dryer was used in different conditions of air temperature (50 ºC and 70 ºC) and air speed (0.9 m s-1 and 1.5 m s-1). Drying curves were obtained for each experimental test. The bioactive potential was reflected in the determination of total phenolic content, antioxidant activity and color parameters. Among the moisture equilibrium predictions between the GAB, BET and Peleg models, the first showed a better predictable capability. The results showed that in the drying operation, the increase in air temperature and speed influenced the increase in the drying rate and the reduction of time. The values of the effective diffusivity of the olive leaves varied between 2.61 x 10- 9 m2 s-1 and 10.12 x 10-9 m2 s-1. The samples dried until 10% of moisture (wet-basis) showed a good antioxidant activity, higher than 85%, and maintenance of the phenolic compounds regarding the fresh leaves around 70%. Bleaching and yellowing of leaves after drying were observed for all studied conditions and a decrease in green color at 70 ºC and 1.5 m s-1, in this condition the L*a*b* color parameters were 35.39, -5.00 and 42.66, respectively. This study demonstrated that the proper drying condition was at 70 ºC and 1.5 m s-1 for olive leaf drying and these conditions were important to maintain the original characteristics of the leaves and to spend less time in operation. Thus, this paper describe a viable drying process to take advantage of the olive leaf for the benefit of the environment and human health.

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Section: Resultssupporting

confidence: 70%

Effects of different drying conditions on bioactive potential of Brazilian olive leaf

Cagliari

Martiny

Nascimento

et al. 2022

Braz. J. Food Technol.

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“…The value of differential entropy was also estimated and found to mirror the trend for isosteric heat with a decrease from 0.02545 kJ mol −1 K −1 at 1% moisture to 0.0074 kJ mol −1 K −1 at 40% moisture content, indicating that the disorder in the system was strongly moisture dependent. It has been postulated that at lower water activities, the reduced entropies are on account of the restrictive rotation and cross‐interaction of moisture within the monolayer (Oliveira, Rosa, Moraes, & Pinto, 2009).…”

Section: Resultsmentioning

confidence: 99%

Moisture sorption behavior and thermodynamic properties of dry‐crystallizedPalada payasam(rice flakes milk pudding) mix determined using the dynamic vapor sorption method

Deshmukh

Ravindra

Jose

et al. 2020

J. Food Process. Preserv.

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Abbreviations: %P, mean relative percent deviation; Ф, spreading pressure (J/m 2); ∆S, change in specific entropy (kJ/mol K); A m , area of a water molecule (1.06 × 10-19 m 2); AOAC, Association of Official Analytical Chemists; a w , water activity; BDDT, Brunauer-Deming-Deming-Teller; BET, Brunauer-Emmett-Teller; dm/dt, rate of change of mass with temperature; DVS, dynamic vapor sorption; EMC, equilibrium moisture content; GAB, Guggenheim-Anderson-De Boer; H L , latent heat of vaporization of pure water (kJ/mol); K B , Boltzmann's constant (1.38 × 10-23 J/K); N, number of adsorbed monolayers; n, number of data points; N A , Avogadro's number (6 × 10 26 molecules/kg mol); R, universal gas constant (8.314 × 10-3 kJ/ mol K); RH, relative humidity; q st , net isosteric heat of sorption (kJ/mol); Q st , isosteric heat of sorption (kJ/mol); R 2 , coefficient of determination; T hm , harmonic mean temperature; UK, United Kingdom.

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“…The constant C determines the binding force of water molecules to the primary sites on the product surface (Bhusari et al, 2016), and ranged from 0.3951 (T4) to 117.1637 (CT). Oliveira et al (2009b) found for Spirulina platensis C values ranging from 36.14 to 37.41.…”

Section: Moisture Adsorption Isothermsmentioning

confidence: 92%

Utilization of Chlorella sp. as biostimulant in the germination of melon seeds (Cucumis melo L.)

Lima¹,

Queiroz²,

Figueirêdo³

et al. 2020

JAS

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Bioactive microalgae compounds have been shown to be excellent stimulants for seed germination. This study aimed at the production of biomass of Chlorella sp. through the modulation of the culture medium and its further use as bioestimulant in melon seed germination (Cucumis melo L.). Chlorella sp. cells were grown in medium containing distinctive levels of nitrogen (N), phosphorus (P), potassium (K) and carbon (C), and analyzes of yield, hygroscopic behavior and the amino acid profile of the biomass were carried out for all treatments. In addition, mechanical hydrolysis of the biomass through high-energy wet grinding was performed, obtaining suitable particle size. After biomass characterization, an aqueous solution of the hydrolyzate was used for biostimulation of melon seeds. The different growth medium composition affected biomass yield and amino acid profile. The most significant effects for seed biostimulation were obtained during growth in medium containing intermediary or low levels of NPK and C, with germination index (GI) of 92 and 95%, and germination speed index (GSI) of 8.00000 and 8,26087 seedlings.day-1, respectively. It is concluded that the modulation of the cultivation of Chlorella sp. is a viable strategy for the production of active compounds. The hydrolysates of Chlorella sp. demonstrated a biostimulant potential and can be a source of molecules for many applications in agriculture.

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Moisture sorption characteristics of microalgae Spirulina platensis

Cited by 19 publications

References 25 publications

Effects of different drying conditions on bioactive potential of Brazilian olive leaf

Effects of different drying conditions on bioactive potential of Brazilian olive leaf

Moisture sorption behavior and thermodynamic properties of dry‐crystallizedPalada payasam(rice flakes milk pudding) mix determined using the dynamic vapor sorption method

Utilization of Chlorella sp. as biostimulant in the germination of melon seeds (Cucumis melo L.)

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