Heterogeneous Optical Fiber Sensor System for Temperature and Turbidity Assessment in Wide Range.

This paper presents the development of an optical fiber sensor system for multiparametric assessment of temperature and turbidity in liquid samples. The sensors are based on the combination between fiber Bragg gratings (FBGs), intensity variation and surface plasmon resonance (SPR) sensors. In this case, the intensity variation sensors are capable of detecting turbidity with a resolution of about 0.5 NTU in a limited range between 0.02 NTU and 100 NTU. As the turbidity increases, a saturation trend in the sensor is observed. In contrast, the SPR-based sensor is capable of detecting refractive index (RI) variation. However, RI measurements in the turbidity calibrated samples indicate a significant variation on the RI only when the turbidity is higher than 100 NTU. Thus, the SPR-based sensor is used as a complementary approach for the dynamic range increase of the turbidity assessment, where a linearity and sensitivity of 98.6% and 313.5 nm/RIU, respectively, are obtained. Finally, the FBG sensor is used in the temperature assessment, an assessment which is not only used for water quality assessment, but also in temperature cross-sensitivity mitigation of the SPR sensor. Furthermore, this approach also leads to the possibility of indirect assessment of turbidity through the differences in the heat transfer rates due to the turbidity increase.

Optical Strain Gauge Prototype Based on a High Sensitivity Balloon-like Interferometer and Additive Manufacturing.

An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber's curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/µÏµ.

New topical microemulsions of etofenamate as sufficient management of osteoarthritis

Abstract In this study, microemulsions containing etofenamate were prepared and evaluated as dermal delivery carriers. The developed microemulsions consist of oleic acid, Span 80, Tween 20, Cremophor EL, Transcutol and ethanol. The percentage of etofenamate loading in the microemulsions was 5% (w/w). The characterization of formulations included droplet size, zeta potential, pH, conductivity, PDI, refractive index and viscosity. Moreover, ex vivo penetration study was carried out using mice abdominal skin. The developed formulations were analyzed for their cytotoxicity via MTT assay and tested for their anti-inflammatory properties opposed to LPS-stimulated nitrite prοduction in RAW 264.7 cells. As ideal formulation, M2ETF, was chosen due to its greater permeation, lower penetration as well as higher anti-inflammatory

Refractive Index Formula of Blood as a Function of Temperature and Concentration.

The analysis of blood parameters is main procedure for defining the patient's condition. The refractive index of blood was calculated using the experimental data for a medical application and diagnostic purposes. There is small change in the refractive indices with changing with the personal conditions, illness, parasitization, temperature and others. Theoretical simulations of the refractive index of blood are difficult, and it is unpredictable in different conditions. We proposed a new formula for the refractive index of blood as a function of wavelength, concentration, and temperature by using the genetic programming method. Input parameters were temperature (°C), concentration (g/L), and wavelength (nm). The refractive index values of blood were the output parameters. A total of 492 training and testing sets were selected in the spectral range of 436 to 1550 nm, in the temperature range of 20-45 °C and the concentration of 0-200 g/L HbC. The model proposes the refractive index formula blood for all the input parameters given in the range without need of extra parameters. The results are good agreement with experimental measurements in the literature and compared to Sellmeier equation.

Binding Analysis of Functionalized Multimode Optical-Fiber Sandwich-like Structure with Organic Polymer and Its Sensing Application for Humidity and Breath Monitoring.

In recent years, the chemical modification of optical fibers (OFs) has facilitated the manufacture of sensors because OFs can identify several analytes present in aqueous solutions or gas phases. Nevertheless, it is imperative better to understand the chemical interactions in this molecular system to generate low-cost and efficient sensors. This work presents a theoretical and experimental study of organic polymeric functionalized OF structures and proposes a cost-effective alternative to monitor breathing and humidity. The device is based on silicon optical fibers functionalized with (3-Aminopropyl) triethoxysilane (APTES) and alginate. The theoretical analysis is carried out to validate the activation of the silicon dioxide fiber surface; moreover, the APTES-alginate layer is discussed. The computational simulation suggests that water can be absorbed by alginate, specifically by the calcium atom linked to the carboxylic acid group of the alginate. The analysis also demonstrates a higher electrostatic interaction between the water and the OF-APTES-alginate system; this interaction alters the optical fiber activated surface's refractive index, resulting in transmission power variation. The humidity analysis shows a sensitivity of 3.1288 mV/RH, a time response close to 25 s, and a recovery time around 8 s. These results were achieved in the range of 50 to 95% RH. Moreover, the recovery and response time allow the human breath to be studied. The proposed mechanism or device is competitive with prior works, and the components involved made this sensor a cost-effective alternative for medical applications.

In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor.

In this paper, we propose a highly sensitive temperature sensor based on two cascaded Mach-Zehnder interferometers (MZIs) that work using the Vernier effect. The all-fiber MZIs were assembled by splicing a segment of capillary hollow-core fiber (CHCF) between two sections of multimode fibers (MMFs). This cascaded configuration exhibits a temperature sensitivity of 1.964 nm/°C in a range from 10 to 70 °C, which is ~67.03 times higher than the sensitivity of the single MZI. Moreover, this device exhibits a high-temperature resolution of 0.0153 °C. A numerical analysis was carried out to estimate the devices' temperature sensitivity and calculate the magnification of the sensitivity produced by the Vernier effect. The numerical results have an excellent agreement with the experimental results and provide a better insight into the working principle of the MZI devices. The sensor's performance, small size, and easy fabrication make us believe that it is an attractive candidate for temperature measurement in biological applications.

Influence of Filler Composition on the Refractive Index of Four Different Enamel Shades of Composite Resins.

AIM AND OBJECTIVE: The purpose of this study was to measure the refractive index of four commercially available enamel resin composites, using optical coherence tomography (OCT) and their relationship with the atomic composition of the composite resin fillers utilizing an energy-dispersive X-ray fluorescence spectrometer (EDX). MATERIALS AND METHODS: Four different enamel composites, namely Enamel HRi color UE3, Enamel HFO color GE3, Vit-l-escence color Pearl Frost, and Amelogen Plus color Enamel White were tested. For each composite, disks with different thicknesses were fabricated and then light-cured according to the manufacturer's instructions. The disks were then stored in deionized water under 36.5 °C for at least 7 days. Each of the samples from the four different groups was measured in five distinctive points to analyze the optical and physical length using optical coherence tomography (OCT). Elemental analysis of all four different enamel shades of the composite was done using an EDX. RESULTS: The filler contents showed interesting differences in elemental composition and concentration; however, Si seemed to be a common filler component. The HRi composite presented a distinctive composition compared to other materials and was the only composite that showed a smaller percentage of SiO2, and also was the only composite that contained compounds, such as P2O5, ZnO, CaO, La2O3, and V2O5. The optical coherence tomography analysis showed the refractive index values of all tested enamel composites. Among the four different enamel composite resins tested, the enamel HRi composite demonstrated the most ideal refractive index to mimic natural enamel. CONCLUSION: The enamel HRi composite demonstrated a distinctive filler composition and this could be the main reason behind its higher refractive index. Nonetheless, it remains unclear how much of an impact this feature has in the final esthetic outcome of anterior composite restorations, where many other optical phenomena are also important. CLINICAL SIGNIFICANCE: The clinical success of any esthetic restorative procedure depends on diagnosing the proper treatment plan and also on executing this treatment with the right materials. On direct esthetic restorations, knowing the optical properties of such materials is fundamental, as they should be able to replicate both natural enamel and dentin. How to cite this article: Beolchi RS, Mehta D, Pelissier B, et al. Influence of Filler Composition on the Refractive Index of Four Different Enamel Shades of Composite Resins. J Contemp Dent Pract 2021;22(5):557-561.

Comparação das medidas refratométricas através da utilização do Photoscreener 2win® e da retinoscopia manual em pré-escolares assintomáticos / Comparison of refractometric measurements using 2win® Photoscreener and manual retinoscopy in asymptomatic preschoolers

RESUMO Objetivos: Avaliar a sensibilidade, especificidade e acurácia da refratometria obtida através do aparelho photoscreener 2WIN® como método de rastreio de ametropias com indicação de prescrição de óculos pelos critérios da Sociedade Brasileira de Oftalmopediatria em crianças assintomáticas, de origem extra-hospitalar, de 6 a 36 meses de idade, e determinar se a cicloplegia influencia a capacidade de rastreio do aparelho. Métodos: Cento e setenta e oito (178) de crianças com idades entre 6 e 36 meses tiveram sua refratometria mensurada pelo método padrão-ouro, a retinoscopia manual sob cicloplegia, e pelo método em teste, o photoscreener 2WIN®, antes e após a cicloplegia. Resultados: O photoscreener 2WIN® é capaz de identificar aqueles pacientes que deveriam receber prescrição de óculos pelos critérios da Sociedade Brasileira de Oftalmopediatria com sensibilidade de 100%, especificidade de 93,18% e acurácia de 93,26%, quando comparado a retinoscopia estática. Sob cicloplegia, o 2WIN® mantém sensibilidade de 100%, porém aumenta sua especificidade para 96,59% e a acurácia para 96,63%. Conclusão: O photoscreener 2WIN® se mostrou altamente sensível, específico e acurado para uso como equipamento de triagem daqueles pacientes de 6 a 36 meses que se beneficiariam do uso de óculos pelos critérios da Sociedade Brasileira de Oftalmopediatria, com discreto aumento da especificidade e acurácia quando aplicado em pacientes cicloplegiados.

ABSTRACT Objective: Evaluate the sensitivity, specificity e accuracy of the ocular refraction measured by the 2WIN® photoscreener as a screening method to identify children in need of spectacles prescription according to the criteria published by the Brazilian Society of Pediatric Ophthalmology (BSPO) in asymptomatic children, 6 to 36 months old, and determine the impact of cycloplegia in the sensitivity, specificity and accuracy of this method. Methods: One hundred seventy-eight (178) eyes of asymptomatic children between the ages of 6 and 36 months have been submitted to ocular refraction measurements by the gold-standard method, the manual retinoscopy under cycloplegia, and the method been tested, the 2WIN® photoscreening, both before and under cycloplegia. Results: The 2WIN® photoscreener before cycloplegia was able to identify those patients in need of spectacles prescription according to the criteria published by the BSPO with 100% sensitivity, 93.18% specificity and 93.26% accuracy, when compared to the manual retinoscopy under cycloplegia. The 2WIN® photoscreener under cycloplegia maintained a sensitivity of 100%, but increased specificity to 96.59% and accuracy to 96.63%. Conclusion: The 2WIN® photoscreener before cycloplegia showed high sensitivity, specificity, and accuracy in detection of patients in need of spectacles prescription according to the criteria published by the BSPO in the tested population, with minor increase in specificity and accuracy when the measurements were performed under cycloplegia.

Evaluation of tea tree oil physicochemical features and its antimicrobial activity against Cutibacterium acnes (Propionibacterium acnes) ATCC 6919 / [Evaluación de las características fisicoquímicas y de la actividad antimicrobiana del aceite del árbol de té contra Cutibacterium acnes (Propionibacterium acnes) ATCC 6919].

Introduction: Tea tree oil is an essential oil recognized for its antimicrobial properties. Objective: To evaluate the composition, features, and antimicrobial effect at 2% v/v, and its minimal inhibitory concentration (MIC) against Cutibacterium acnes (Propionibacterium acnes). Materials and methods: Three different batches of tea tree oil were evaluated. We characterized its chemotype by gas chromatography and its 2% v/v antimicrobial activity against C. acnes by agar diffusion assay (guide M11-A8 CLSI). Results: The three batches of oil had the chemotypes required by the ISO 4730 standard, which indicates that it is a high-quality product. Additionally, they had 30% to 40% of terpinen-4-ol, a compound that favors its antimicrobial activity. Antimicrobial activity against C. acnes for all batches had a concentration-dependent effect with microbial growth inhibitory activity in all assays at 2% v/v. The MIC obtained against C. acnes for all batches was 0.25% v/v. The antimicrobial activity of tea tree oil against this microorganism has been previously reported with a MIC between 0.05% and 1.25% v/v, a range that covers the one obtained in this study. Conclusion: These results show the high quality of the oil and its capacity as an antibacterial agent against C. acnes. New studies should be conducted to confirm its activity and that of its components in isolates of the microorganism from patients with acne vulgaris.

Introducción. El aceite del árbol de té es un aceite esencial reconocido por sus propiedades antimicrobianas. Objetivos. Evaluar la composición, características y efecto antimicrobiano del aceite al 2 % del árbol de té y su concentración inhibitoria mínima (CIM) contra Cutibacterium acnes (Propionibacterium acnes). Materiales y métodos. Se evaluó el quimiotipo en tres lotes diferentes de este aceite mediante cromatografía de gases, así como su actividad antimicrobiana en concentración al 2 % v/v y la CIM contra C. acnes mediante ensayo de difusión en agar (guía M11-A8 CLSI). Resultados. Los lotes evaluados presentaron los quimiotipos ajustados a la norma ISO 4730, lo que indicó la alta calidad del producto. Los lotes contenían de 30 a 40 % de terpinen-4-ol, compuesto que favorece la actividad antimicrobiana, la cual presentó en todos los lotes un efecto dependiente de la concentración contra C. acnes, con una inhibición del crecimiento microbiano en concentración al 2 % v/v en todas las pruebas. La concentración inhibitoria mínima fue de 0,25 % v/v. La actividad antimicrobiana del aceite del árbol de té contra este microorganismo ya ha sido reportada con una concentración inhibitoria mínima entre 0,05 y 1,25 % v/v, rango que cobija la obtenida en este estudio. Conclusiones. Los resultados evidenciaron la gran calidad de este producto y su capacidad como agente antibacteriano contra C. acnes. Se deben hacer estudios con otros aislamientos del microorganismo provenientes de pacientes con acné vulgar para confirmar su actividad general y la de cada uno de sus componentes.

Surface Plasmon Resonances in Sierpinski-Like Photonic Crystal Fibers: Polarization Filters and Sensing Applications.

We investigate the plasmonic behavior of a fractal photonic crystal fiber, with Sierpinski-like circular cross-section, and its potential applications for refractive index sensing and multiband polarization filters. Numerical results were obtained using the finite element method through the commercial software COMSOL Multiphysics®. A set of 34 surface plasmon resonances was identified in the wavelength range from λ=630 nm to λ=1700 nm. Subsets of close resonances were noted as a consequence of similar symmetries of the surface plasmon resonance (SPR) modes. Polarization filtering capabilities are numerically shown in the telecommunication windows from the O-band to the L-band. In the case of refractive index sensing, we used the wavelength interrogation method in the wavelength range from λ=670 nm to λ=790 nm, where the system exhibited a sensitivity of S(λ)=1951.43 nm/RIU (refractive index unit). Due to the broadband capabilities of our concept, we expect that it will be useful to develop future ultra-wide band optical communication infrastructures, which are urgent to meet the ever-increasing demand for bandwidth-hungry devices.

Chemical composition and lipid profile of mare colostrum and milk of the quarter horse breed.

The objective of this study was to characterize the chemical composition and lipid profile of colostrum and milk of purebred Quarter Horse mares. Thirty-four (34) purebred mares were selected, which were then separated into groups according to age, birth order and lactation stage. Colostrum samples were collected in the first six hours after delivery and milk samples from the 7th postpartum day, with intervals of 14 days until the end of lactation. The samples were refrigerated and sent to the Milk Laboratory of the University (Laboleite-UFRN), where they were analyzed for chemical composition. Colostrum was assessed by refractometry. The lipid profile was determined by gas chromatography through a separation of methyl esters. The data were tabulated and subjected to descriptive statistics and analysis of variance by the F-Test, and the groups were compared by the Tukey test using a significance level of 5%. There was high protein content and reduced lactose content for the colostrum of the Quarter Horse mares, differing from other breeds. The milk composition was not influenced by the mares' age. However, variations in the lactation stage and in the birth order of the Quarter Horse mares altered the milk's chemical composition. There is variation in the lipid composition of milk according to the lactation stage, without changing the characteristic profile of the mares' milk or diminishing the nutritional quality of the lipid fraction.

High Sensitive Biosensors Based on the Coupling Between Surface Plasmon Polaritons on Titanium Nitride and a Planar Waveguide Mode.

High sensitivity biosensors based on the coupling of surface plasmon polaritons on titanium nitride (TiN) and a planar waveguide mode were built; they were proved by sensing three different media: air, water and dried egg white; sensors described here could be useful for sensing materials with a refractive index between 1.0 and 1.6; in particular, materials of biological interest with a refractive index in the range 1.3-1.6, like those containing biotin and/or streptavidin. They were built by depositing Nb2O5/SiO2/TiN multilayer structures on the flat surface of D-shaped sapphire prisms by using the dc magnetron sputtering technique. Attenuated total reflection (ATR) experiments in the Kretschmann configuration were accomplished for the air/TiN/Prism and S/Nb2O5/SiO2/TiN/Prism structures, S being the sample or sensing medium. ATR spectra for plasmons at the TiN/air interface showed a broad absorption band for angles of incidence between 36 and 85°, with full width at half maximum (FWHM) of approximately 40°. For the S/Nb2O5/SiO2/TiN/Prism structures, ATR spectra showed a sharp reflectivity peak, within the broad plasmonic absorption band, which was associated with Fano resonances. The angular position and FWHM of the Fano resonances strongly depend on the refractive index of the sensing medium. ATR spectra were fitted by using the transfer-matrix method. Additionally, we found that angular sensitivity and figure of merit increase with increasing the refractive index of the sensing medium.

Fluorescence quantum yield of natural dye extracted from Tradescantia pallida purpurea as a function of the seasons: Preliminary bioapplication as a fungicide probe for necrotrophic fungi.

In this work, over the course of four seasons (12 months), we have monitored the fluorescence quantum efficiency (η) from two sets (S1 and S2) of fresh natural dye extracts from the leaves of Tradescantia pallida purpurea. The natural dye was extracted in aqueous solutions from leaves collected from regions with a predominance of shade (S1) and sun (S2) during the day. The thermo-optical parameter fractional thermal load (φ) was measured using conical diffraction (CD) patterns caused by thermally driven self-phase modulation, for η determination in both sets of solutions. Fluorescence measurements corroborate the CD results, and the η values are, on average, slightly higher (~ 11%) in the summer than in the other seasons for both sets of samples (S1 and S2). In addition, the experimental results are presented using natural dye extracted from Tradescantia pallida purpurea as a fungicide probe in Fusarium solani, Sclerotinia sclerotiorum, and Colletotrichum gloeosporioides fungi. The promising fungicide results obtained for the aqueous natural dye extract were compared with those obtained for other natural dyes and fungi. The fungi tested are of the necrotrophic group and constitute important pathosystems in Brazil, causing diseases in several crops that synthetic fungicides often cannot control or do so with low efficiency.

Characterization of molecular properties of wheat starch from three different types of breads using asymmetric flow field-flow fractionation (AF4).

In this study, molecular properties of wheat starch from three different types of breads were analyzed using asymmetric flow field-flow (AF4) connected to multi-angle light scattering (MALS) and differential refractive index (dRI) detectors. This analysis allowed the determination of molecular properties, i.e. molar mass (M), root-mean-square radius (rrms), apparent density (ρapp) and conformation. Complementary analyses, such as resistant starch and amylose content, were also performed. The results show that wheat starch extracted from breads can have different properties reflected in changes in M, rrms and ρapp. In addition, the results suggest that some of the changes in molecular properties may be related to the presence of resistant starch.

Development of in-house materials for the verification of specific gravity measurements: Homogeneity, stability, and proficiency studies.

We developed and evaluated the properties of in-house urine reference materials for the verification of laboratory refractometers, which are frequently used in clinical chemistry and doping testing laboratories. Urine was gathered from 26 healthy volunteers (16 male 30 ± 5 years old and 10 female 29 ± 4 years old), from which two urine batches were obtained: one with a low specific gravity (1.012± 0.003) and the other with a high specific gravity (1.027 ± 0.003). Homogeneity studies were conducted over 20 consecutive days. For short-term stability studies, aliquots of both urine batches were stored at -20 ± 2°C; 3 ± 2°C; 20 ± 2°C; 45 ± 2°C for 0, 2, 7, 14 and 35 days, under both light and dark conditions. Similarly, another study was conducted to measure the long-term stability of urine at -20 ± 2°C, over a 24-month evaluation period. Our data showed that the urine was homogeneous and stable at -20 ± 2°C, 3 ± 2°C, 20 ± 2°C, and 45 ± 2°C under both light and dark conditions. In all cases, the urine was evaluated by specific gravity and no statistically significant differences (p ≤ 0.05) were recorded. Additionally, a proficiency test was conducted in collaboration with 15 ISO/IEC 17025 accredited laboratories, and z-scores and performance factors were evaluated. These data indicate that this material could be used for the verification of refractometers.

Efeito da forma de aquecimento em parâmetros de qualidade e identidade de óleos vegetais / Effect of the heating means in quality and identity parameters of vegetable oils

Objetivou-se com este trabalho avaliar parâmetros de identidade e qualidade de óleo de abacate produzido nacionalmente, comparativamente a azeite de oliva e óleo de arroz, após aquecimento em bloco digestor ou micro-ondas. Avaliaram-se amostras sem aquecimento (controle) e aquecidas por 1:30 h em bloco digestor ou 3 min em micro-ondas. Determinaram-se a acidez e os índices iodo e refração. Os resultados indicaram que houve aumento de acidez, redução no índice de iodo e índice de refração após o aquecimento. Apesar do maior valor de acidez após o aquecimento, o óleo de abacate sofreu menor elevação em relação ao controle (cerca de 4 vezes) do que as demais amostras. O impacto do aquecimento foi maior no óleo de arroz, seguido do azeite de oliva. O aquecimento por micro-ondas afetou mais a qualidade das amostras que o aquecimento em bloco digestor.(AU)

Avaliação de parâmetros de qualidade do óleo de Palma BRS Manicoré / Evaluation of Palma oil BRS Manicoré quality parameters

O óleo de palma híbrido é considerado um produto rico em conteúdo insaturado e mais resistente a doenças. Objetivou-se analisar parâmetros que indicam a qualidade do óleo de Palma BRS Manicoré. As amostras foram avaliadas quanto ao índice de saponificação, índice de refração, compostos fenólicos totais, atividade antioxidante e densidade. Os resultados obtidos foram submetidos à Análise de Variância (ANOVA). Os valores obtidos para índice de refração e índice de saponificação foram pouco inferiores ao limite estabelecido pela legislação. As amostras apresentaram-se ricas em compostos antioxidantes que são benéficos a saúde humana em sua composição. Conclui-se que o óleo UNAUE apresenta atividade antioxidante, o que torna indispensável sua utilização na dieta humana e para outros fins.(AU)

Avaliação de parâmetros de qualidade do óleo de Palma BRS Manicoré / Evaluation of Palma oil BRS Manicoré quality parameters

O óleo de palma híbrido é considerado um produto rico em conteúdo insaturado e mais resistente a doenças. Objetivou-se analisar parâmetros que indicam a qualidade do óleo de Palma BRS Manicoré. As amostras foram avaliadas quanto ao índice de saponificação, índice de refração, compostos fenólicos totais, atividade antioxidante e densidade. Os resultados obtidos foram submetidos à Análise de Variância (ANOVA). Os valores obtidos para índice de refração e índice de saponificação foram pouco inferiores ao limite estabelecido pela legislação. As amostras apresentaram-se ricas em compostos antioxidantes que são benéficos a saúde humana em sua composição. Conclui-se que o óleo UNAUE apresenta atividade antioxidante, o que torna indispensável sua utilização na dieta humana e para outros fins.

Efeito da forma de aquecimento em parâmetros de qualidade e identidade de óleos vegetais / Effect of the heating means in quality and identity parameters of vegetable oils

Objetivou-se com este trabalho avaliar parâmetros de identidade e qualidade de óleo de abacate produzido nacionalmente, comparativamente a azeite de oliva e óleo de arroz, após aquecimento em bloco digestor ou micro-ondas. Avaliaram-se amostras sem aquecimento (controle) e aquecidas por 1:30 h em bloco digestor ou 3 min em micro-ondas. Determinaram-se a acidez e os índices iodo e refração. Os resultados indicaram que houve aumento de acidez, redução no índice de iodo e índice de refração após o aquecimento. Apesar do maior valor de acidez após o aquecimento, o óleo de abacate sofreu menor elevação em relação ao controle (cerca de 4 vezes) do que as demais amostras. O impacto do aquecimento foi maior no óleo de arroz, seguido do azeite de oliva. O aquecimento por micro-ondas afetou mais a qualidade das amostras que o aquecimento em bloco digestor.