Evaluation of the thermal diffusivity of vegetable oils during frying by Thermal Lens Spectrometry

Lima, S.M.; Bannwart, E.S.; Oliveira, R.G.; Andrade, Luís Humberto da Cunha; Ré, Patrícia Vieira Del; Jorge, Neuza; Pedrochi, F.; Constantini, R.; Medina, A. N.; Baesso, M. L.

doi:10.1140/epjst/e2008-00501-x

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…33 In oils, when there is any type of change, as that induced by thermal oxidation, for example, the generated spectrum shows a band shift (bathochromic effect) and increased absorption intensity. 34 This result may be associated with a decrease of the iodine index previously reported (Table 1), showing the importance of combining analytical techniques in the search for more accurate results.…”

Section: Resultsmentioning

confidence: 71%

Refining of buriti oil (Mauritia flexuosa) originated from the brazilian cerrado: physicochemical, thermal-oxidative and nutritional implications

Lourdes¹,

Araujo²,

Epaminondas³

et al. 2012

J. Braz. Chem. Soc.

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Objetivou-se comparar os parâmetros físico-químicos e termo-oxidativos do óleo bruto de buriti com o refinado, como também determinar o teor de vitamina A, perfil lipídico e potencial antioxidante destes óleos. Amostras de óleo bruto e refinado foram avaliadas quanto à viscosidade, densidade relativa, índices de refração, acidez, ácidos graxos livres, peróxido e de iodo, grau de oxidação lipídica por UV-Vis, termogravimetria, calorimetria, capacidade antioxidante, teor de vitamina A e perfil de ácidos graxos. O refino do óleo diminuiu o percentual de ácidos graxos livres e os índices de acidez, de iodo e de peróxido, apresentando maior estabilidade termo-oxidativa que o óleo bruto. Porém sua capacidade antioxidante, o teor de vitamina A e o de ácidos graxos insaturados foram reduzidos em relação ao óleo bruto. Logo, sugere-se a otimização do processo de refino para minimizar perdas nutricionais no óleo de buriti, que por suas características pode ser considerado um alimento funcional.The objective of this study was to compare the physicochemical, thermo-oxidative and nutritional characteristics of crude and refined buriti oil. Crude and refined oil samples were evaluated for viscosity, relative density, refraction, acidity, free fatty acids, peroxide and iodine, lipid oxidation degree by UV-Vis, thermogravimetry, calorimetry, in vitro antioxidant capacity, vitamin A content and fatty acids profile. The refining process decreased the free fatty acids percentage and acidity, peroxide and iodine indexes, with greater thermal-oxidative stability, which is critical for its use in cooking food. However, its antioxidant capacity, vitamin A and unsaturated fatty acids contents were reduced compared to crude oil. Therefore, it is suggested to optimize the refining process to minimize nutritional losses in buriti oil, which due to its characteristics, can be considered a functional food.

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Section: Resultsmentioning

confidence: 71%

Refining of buriti oil (Mauritia flexuosa) originated from the brazilian cerrado: physicochemical, thermal-oxidative and nutritional implications

Lourdes¹,

Araujo²,

Epaminondas³

et al. 2012

J. Braz. Chem. Soc.

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“…In the simulations, we consider characteristic parameters of soybean oil. Experimental evidence show the high potentiality of the thermal lens method in the characterization of vegetable oils, mainly due to its photosensibility 30 and the fact that this fluid presents thermal and concentration contributions for the total phase shift. In addition, we also analyze aqueous solution of Eosin, where only thermal effects are significative.…”

Section: ■ Numerical Algorithmmentioning

confidence: 99%

Role of Photophysics Processes in Thermal Lens Spectroscopy of Fluids: A Theoretical Study

et al. 2014

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Photophysics processes are ubiquitous in nature and difficult to be quantitatively characterized by conventional spectroscopy. Alternatively, pump-probe methods have been widely applied to study these complex processes. In this context, the thermal lens technique is a precise spectroscopic tool for material characterization and presents a wide range of applications in chemical analysis. Here, we present an all numerical approach to analyze the dynamics of photophysics processes and to identify the role of individual contributions of photoreaction and mass diffusion in the thermal lens experiments. The results are essential for a proper understanding of the dominant physical mechanisms in laser-induced photodegradation, which allow precise data analysis of the effects in photosensitive fluids.

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“…As noted for the long time regime (>0.5 s), there is a divergence between the experimental data and the theoretical curves, which are more pronounced in the high power regime. This effect was also observed in other solutions and biodiesel samples and can be related to the MD effect; [14][15][16] therefore, this effect needs to be considered during the fit procedure. As previously mentioned, because there are no PCR effects expected in these samples with the excitation wavelength and used power regime, only the MD effect is responsible for the observed disagreement.…”

Section: Resultsmentioning

confidence: 80%

“…Thermal lens (TL) spectroscopy has been extensively used to characterize different materials, including solutions such as oil and biodiesel. [13][14][15][16] The TL procedure centers on the observation of the heat generated in the sample when it absorbs energy from a laser beam with a Gaussian intensity profile. The absorbed energy induces a temperature variation in the sample that is larger in the center than at the border of the beam, following the spatial distribution of the laser beam intensity.…”

Section: Introductionmentioning

confidence: 99%

Thermal lens spectroscopy for the differentiation of biodiesel-diesel blends

Ventura

Simionatto

Andrade

et al. 2012

Review of Scientific Instruments

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Thermal lens (TL) spectroscopy was applied to biofuels to test its potential to distinguish diesel from biodiesel in blended fuels. Both the heat and mass diffusion effects observed using a TL procedure provide significant information about biodiesel concentrations in blended fuels. The results indicate that the mass diffusivity decreases 32% between diesel and the blend with 10% biodiesel added to the diesel. This simple TL procedure has the potential to be used for in loco analyses to certify the mixture and quality of biodiesel-diesel blends.

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Evaluation of the thermal diffusivity of vegetable oils during frying by Thermal Lens Spectrometry

Cited by 9 publications

References 5 publications

Refining of buriti oil (Mauritia flexuosa) originated from the brazilian cerrado: physicochemical, thermal-oxidative and nutritional implications

Refining of buriti oil (Mauritia flexuosa) originated from the brazilian cerrado: physicochemical, thermal-oxidative and nutritional implications

Role of Photophysics Processes in Thermal Lens Spectroscopy of Fluids: A Theoretical Study

Thermal lens spectroscopy for the differentiation of biodiesel-diesel blends

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