High-power ultrasound bleaching technique for canola oil (Brassica napus L.): Pigments removal and quality parameters.

Canola seeds (Brassica napus L.) are among the most commonly used seeds in Mexico for vegetable oil production. This is based on the high yield and content of polyunsaturated and monounsaturated fatty acids. During oil bleaching, it is important to maintain fatty acids in their cis configuration because of the health concerns associated with trans-fatty acid consumption. In this sense, the industrial processing parameters employed for this purpose present some limitations, such as high temperatures and long times, which may change the cis configuration to trans. In addition, the amount of bleaching clay employed for this process could be a source of contamination because it is disposed of after treatment. Therefore, the aim of this study was to develop a bleaching process for canola oil using high-power ultrasound (US). US processing was applied to nine treatments with different processing times (60, 75, and 90 min), clay percentages (1, 2, and 3%), and temperatures (60 and 80 °C) to determine the concentrations of chlorophyll a and b (µg chlo/100 g oil), carotenes (µg ß-carotene/100 g oil), color (L*, a*, b*, C*, and h°), iodine value (g I2/100 g oil), and finally carrying out a spectroscopic analysis (ATR-FTIR and Raman). A conventional bleaching treatment (100 °C for 180 min, 3% bleaching clay) was used as a control. The results revealed that US treatments with 2% clay at 60 °C for 60 and 90 min eliminated most of the chlorophyll compounds (98%). However, in terms of carotenes reduction, these identical treatments exhibited a similar tendency to that of the control (approximately 30% decrease). These findings also affected the sample color, in which US treatments revealed chromatic coordinates that indicated yellow tones with chroma values that were more intense than those in the control samples. In terms of the iodine value, such treatments fulfilled the international standards for vegetable oils (90-100 g I2/100 g oil). Finally, the spectroscopic study revealed no trans configurations or the presence of different chemical compounds after US treatment, because neither of them presented typical peaks for those molecular configurations. In this regard, US can be a useful methodology for bleaching vegetable oils, helping to reduce time, and bleaching clay with similar pigment reduction results.

Use of high-intensity ultrasound as a pre-treatment for complex coacervation from whey protein isolate and iota-carrageenan.

The aim of this work was to evaluate the influence of high intensity ultrasound (HIUS) treatment on the molecular conformation of whey protein isolated (WPI) as a previous step for complex coacervation with iota carrageenan (IC) and its effect on the surface functional properties of complex coacervates (CC). Both biopolymers were hydrated (1% w/w) separately. A WPI suspension was treated with an ultrasonic bath (40 kHz, 600 W, 30 and 60 min, 100% amplitude). A non-sonicated protein was used as a control. Coacervation was achieved by mixing WPI and IC dispersions (10 min). FTIR-ATR analysis (400-4000 cm-1) detected changes after sonication on WPI secondary structure (1600-1700 cm-1), electrostatic interaction between WPI and IC by electronegative IC charged groups like sulfate (1200-1260 cm-1), anhydrous oxygen of the 3.6 anhydro-D-galactose (940-1066 cm-1) and the electropositive regions of WPI. Rheology results showed pseudoplastic behavior of both IC and WPI-IC with a significant change in viscosity level. Further, HIUS treatment had a positive effect on the emulsifying properties of the WPI-IC coacervates, increasing the time foaming (30 min) and emulsion stability (1 month) percentage. HIUS and complex coacervation proved to be an efficient tool to improve the surface functional properties of WPI.

High-intensity ultrasound pretreatment influence on whey protein isolate and its use on complex coacervation with kappa carrageenan: Evaluation of selected functional properties.

The aim of this work was to evaluate the influence of high-intensity ultrasound (HIUS) treatment on whey protein isolate (WPI) molecular structure as a previous step for complex coacervation (CC) with kappa-carrageenan (KC) and its influence on CC functional properties. Protein suspension of WPI (1% w/w) was treated with an ultrasound probe (24 kHz, 2 and 4 min, at 50 and 100% amplitude), non HIUS pretreated WPI was used as a control. Coacervation was achieved by mixing WPI and KC dispersions (10 min). Time and amplitude of the sonication treatment had a direct effect on the molecular structure of the protein, FTIR-ATR analysis detected changes on pretreated WPI secondary structure (1600-1700 cm-1) after sonication. CC electrostatic interactions were detected between WPI positive regions, KC sulfate group (1200-1260 cm-1), and the anhydrous oxygen of the 3,6 anhydro-D-galactose (940-1066 cm-1) with a partial negative charge. After ultrasound treatment, a progressive decrease in WPI particle size (nm) was detected. Rheology results showed pseudoplastic behavior for both, KC and CC, with a significant change on the viscosity level. Further, volume increment, stability, and expansion percentages of CC foams were improved using WPI sonicated. Besides, HIUS treatment had a positive effect on the emulsifying properties of the CC, increasing the time emulsion stability percentage. HIUS proved to be an efficient tool to improve functional properties in WPI-KC CC.

Experimental characterization of a biosensor based on a tapered optical fiber for kisspeptin detection.

This paper presents the development of a biosensor based on optical fiber, using a polyclonal antibody kisspeptin receptor as a biological recognition element that is connected to puberty onset and may also help to suppress metastasis in melanoma breast cancer. The fiber surface was chemically prepared to immobilize the antibody. The structural homogeneity of the biosensor, at each stage of the self-assembly, was characterized by Fourier transform infrared spectroscopy and by measurements of the transmission at the output of the biosensor. The morphological homogeneity analysis was performed by optical microscopy and scanning electron microscopy. The biosensor developed was checked to detect kisspeptin in brain tissues by spectral transmission using a superluminescent diode. The data were analyzed using principal component analysis. The interaction of the kisspeptin with its counterpart by means of the evolution of the transmission spectrum as a function of time was observed.

Componentes Principales mediante Espectroscopia FTIR como Técnica de Caracterización Innovadora durante la Diferenciación de Células Madre Pluripotentes a Células Pancreáticas / Principal Components by FTIR Spectroscopy as Innovative Characterization Technique during Differentiation of Pluripotent Stem Cells to Pancreatic Cells

Resumen: Dos de los grandes retos en la biología de las Células Madre (CM) y la Medicina Regenerativa, son el control en la diferenciación de estas células y asegurar la pureza de las células diferenciadas, por lo que es necesario contar con técnicas rápidas, eficientes y precisas para la caracterización de CM y su diferenciación a diferentes linajes celulares. El objetivo de este trabajo fue analizar Células Madre Pluripotentes (CMP) y Células Pancreáticas Diferenciadas (CPD) mediante espectroscopía Infrarroja por Transformada de Fourier (FTIR) y Análisis de Componentes Principales (ACP). Para ello se diferenciaron CMP a CPD, caracterizando el proceso de diferenciación a los días 0, 11, 17 y 21 mediante microscopía óptica y espectroscopia vibracional. Los espectros FTIR se analizaron con el método multivariado de ACP, utilizando su segunda derivada en las regiones de proteínas, carbohidratos y ribosas. Los resultados indican que el ACP permite caracterizar y discriminar CMP y CPD en sus diferentes etapas de diferenciación en las regiones espectrales analizadas. Con lo anterior concluimos que el ACP permite caracterizar química y estructuralmente CMP y diferentes etapas de su diferenciación en una forma rápida, precisa y no invasiva.

Abstract: Two of the greatest challenges in Stem Cells (SCs) biology and regenerative medicine, are differentiation control of SCs and ensuring the purity of differentiated cells. In this sense, fast, efficient and accurate techniques for SCs characterization and their differentiation into different cell lineages are needed. The aim of this study was to analyse Pluripotent Stem Cells (PSCs) and Differentiated Pancreatic Cells (DPCs) by Fourier Transform Infrared (FTIR) spectroscopy and Principal Component Analysis (PCA). For this purpose, we differentiated PSCs toward DPCs, characterizing the differentiation process at different stages (0, 11, 17 and 21 days) through light microscopy and vibrational spectroscopy. FTIR spectra were analysed with the multivariate method of PCA, using the second derivatives in the protein, carbohydrate and ribose regions. The results indicate that the PCA allows to characterize and discriminate PSCs and DPCs at different stages of differentiation in the analysed spectral regions. From these results, we concluded that the PCA allows the chemically and structural characterization of PSCs and the different stages of their differentiation in a fast, accurate and non-invasive way.

Surface-enhanced Raman scattering of the adsorption of pesticide endosulfan on gold nanoparticles.

The absorption of pesticide endosulfan on the surface of gold nanoparticles results from the formation of micrometric structures (1-10 µm) with irregular shape because of the aggregation of individual particles. Such aggregation of gold nanoparticles after absorption of pesticide shows a surface-enhanced Raman scattering (SERS) spectrum, whose intensity depends on the concentration of endosulfan. In addition, the discoloration of the colloidal solution and a diminishing of the intensity of the surface plasmon resonance absorption from individual particles were observed by UV-visible spectroscopy. At the same time, a second band between 638 and 700 nm confirms the formation of aggregates of gold nanoparticles as the concentration of endosulfan increases. Finally, we used the SERS intensity of the S-O stretching vibration at 1239 cm(-1) from the SO3 group as a measure of concentration of pesticide endosulfan. This method could be used to estimate the level of pollution in water by endosulfan in a simple and practical form.

Nonlocal nonlinear refractive index of gold nanoparticles synthesized by ascorbic acid reduction: comparison of fitting models.

In this paper, the nonlinear refractive index of colloidal gold nanoparticles under continuous wave illumination is investigated with the z-scan technique. Gold nanoparticles were synthesized using ascorbic acid as reductant, phosphates as stabilizer and cetyltrimethylammonium chloride (CTAC) as surfactant agent. The nanoparticle size was controlled with the CTAC concentration. Experiments changing incident power and sample concentration were done. The experimental z-scan results were fitted with three models: thermal lens, aberrant thermal lens and the nonlocal model. It is shown that the nonlocal model reproduces with exceptionally good agreement; the obtained experimental behaviour.