A simple, rapid and low cost reversed-phase dispersive liquid-liquid microextraction for the determination of Na, K, Ca and Mg in biodiesel.

In this work a method based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) as sample preparation for the extraction and preconcentration of Na, K, Ca and Mg in biodiesel samples was developed. The analytes determination was performed by flame atomic absorption spectrometry (FAAS), operating in emission mode for Na and K and in absorption mode for Ca and Mg. The extraction/preconcentration step of the analytes was performed by using a mixture of dispersant and extractant solvents (isopropanol and HNO3, respectively) and the aqueous phase containing the analytes was separated by centrifugation. Some parameters such as sample mass, type and volume of dispersant and extractant solutions, HNO3 concentration (extraction solution), use of ultrasound, centrifugation time and temperature were evaluated. During the optimization of RP-DLLME, biodiesel samples were spiked with a multi-element biodiesel B100 (Conostan®) with final concentration of 1.0 µg g-1 of the analytes. Analytes determination was performed by FAAS using external calibration with aqueous reference solutions. The limits of quantification (LOQ) for Na, K, Ca and Mg were 0.04; 0.02; 0.05 and 0.08 µg kg respectively. The accuracy was evaluated by recovery tests, which ranged from 93.9% to 108.1%, with relative standard deviation lower than 3% for all analytes. Then, the proposed method was applied for analytes determination in five biodiesel samples produced from different raw materials. Comparing to conventional methods for elements determination in biodiesel (e.g., dilution with organic solvent, sample digestion, etc.), RP-DLLME combined to FAAS is simple, low cost, low reagents consumption and provides LOQs values significantly below compared to the limits established in the legislation for these elements in biodiesel.

Synthesis and characterization of a low solubility edible film based on native cassava starch.

Films based on cassava starch have been widely used for fruit coating; however, it is necessary to incorporate other polymers in order to improve mechanical properties, once starch only leads to highly hydrophilic films, compromising their application. In this way, a polymeric blend based on cassava starch, chitosan and gelatin was combined with a plasticizer to produce biodegradable films with satisfactory mechanical and barrier properties, in order to be used as fruit coating. The films were prepared by casting method and a statistical design of 23 was used to evaluate the effect of each polymer and what their combinations would influence over the final product. The formation of a physical blend was confirmed by FTIR. It showed low solubility, varying (10 ±â€¯2) % a (23 ±â€¯4) %, Opacity ranging from (1.06 ±â€¯0.04) to (1.55 ±â€¯0.13) AU x nm/mm, thickness from (0.20 ±â€¯0.01) mm to (0.44 ±â€¯0.03) mm and water vapor transmission rate ranging from 25 ±â€¯0.2 to 30 ±â€¯1.4 g s-1 m-2. Lower amounts of starch led to more flexible, less opaque and soluble films, while the combination of higher levels of starch and chitosan was responsible for lowering films water vapor transmission rate. Thus, the films showed interesting properties for fruit surface coating.

Design of composite microparticle systems based on pectin and waste material of propolis for modified l-alanyl-l-glutamine release and with immunostimulant activity.

Catabolic conditions like acquired immunodeficiency syndrome, cancer, and burn can cause immunosuppression. Amino acids such as alanine and glutamine are essential for the activity of the immune system. Propolis is immunostimulant and the waste of propolis extraction has been reused with technological and therapeutic purposes. Therefore, this study describes the association of propolis byproduct extract (BPE) with pectin to prepare spray-dried microparticles containing the dipeptide l-alanyl-l-glutamine as stimulant systems of neutrophils. The use of a factorial design allowed selecting the best formulation, which was characterized by morphology, size, and entrapment efficiency analyses. In addition, the systems were characterized by thermal and X-ray diffraction analysis, Fourier-transform infrared spectroscopy, in vitro drug release, and in vitro cytotoxicity and stimulation test of neutrophils. Small well-structured microparticles with good entrapment efficiency values were achieved. Thermal stability of formulation was observed, and it was proved that pectin, BPE and l-alanyl-l-glutamine were dispersed throughout the matrix. The drug was released from the microparticles during 24 h governed by swelling and diffusion. The drug-loaded formulations showed a significant stimulating effect on neutrophils. These structures could increase the activity of immune cells, and other in vitro and in vivo studies should be performed in the future.

Extraction and application of chia mucilage (Salvia hispanica L.) and locust bean gum (Ceratonia siliqua L.) in goat milk frozen dessert.

A complete factorial design (23) was used to determine the influence of chia mucilage concentration (CM), locust bean gum (LBG) and base maturation time (BMT) on 14 formulations of goat milk frozen dessert. Chia mucilage was obtained by chia grain hydration (1:40) under stirring for 2 h, at 80 °C and pH of 9.0. The samples were centrifuged, as well as lyophilised to compare yields. The extraction yield of lyophilised CM was lower than 10%. The addition of LBG and CM at higher levels, influenced by BMT, increased the moisture content and the apparent viscosity of the base mixture. These formulations presented higher values for texture and lower of overrun due to the difficulty of incorporating and stabilising bubbles during whipping and freezing processes. The melting rate was also dependent on the variables analysed, and a delay in melting was observed, even in the formulations with lower fat content. CM increased the luminosity parameter proportionally to its content and provided a significant reduction of fat (up to 3.10 g 100 g-1) and energy value. The application of CM reduced the texture value, which was an interesting technological characteristic for frozen dessert.