Edwin Elard Garcia-Rojas

Complex coacervates obtained from peptide leucine and gum arabic: Formation and characterization

In this study, interactions between polypeptide-leucine (0.2% w/w) and gum arabic (0.03, 0.06, 0.09, 0.12, and 0.15% w/w) were examined at concentrations of NaCl (0, 0.01, 0.25, 0.3, 0.5mol/l) and at different pH values (from 1.0 to 12.0). Formation of insoluble complex coacervates was highest at pH 4.0. At pH 2.0, which is the pKa of the gum Arabic, the dissociation of precipitate occurred. The pHØ2 positively shifted with the addition of higher concentrations of salt. Samples containing 0.2% PL and 0.03% GA and no salt had higher turbidity and increased formation of precipitates showing greater turbidity and particle sizes. The Fourier transform infrared spectroscopy confirms the complex coacervate formation of leucine and gum arabic, and rheological measurements suggest the elastic behavior of 0.2% PL and 0.03% GA complex. Overall, the study suggests that complex coacervates of PLs could be one feasible ways of incorporating amino acids in food products.

Fatty acids profile of Sacha Inchi oil and blends by 1H NMR and GC-FID.

This study aimed at the characterization of blends of Sacha Inchi oil (SIO) with different ratios of SO (soybean oil) and CO (corn oil) by nuclear magnetic resonance ((1)H NMR), compared with the data obtained by gas chromatography with a flame ionization detector (GC-FID). The (1)H NMR and GC-FID data from different ratios of SIO were adjusted by a second order polynomial equation. The two techniques were highly correlated (R(2) values ranged from 0.995 to 0.999), revealing that (1)H NMR is an efficient methodology for the quantification of omega-3 fatty acids in oils rich in omega-6 fatty acids or vice versa such as SO and CO and, on the other hand, can be used to quantify ω-6 in oils rich in ω-3, such as SIO.

Microencapsulation of sacha inchi oil using emulsion-based delivery systems

In this study, sacha inchi oil (SIO) was microencapsulated by emulsion-based systems using ovalbumin (Ova), pectin (Pec), and xanthan gum (XG), followed by freeze-drying. The microencapsulation was confirmed using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The stability of omega-3 in SIO alone as well as in microencapsulated SIO was assessed by nuclear magnetic resonance (1H NMR) spectroscopy after human gastric simulation (HGS). The SEM results revealed distinct structures for the two types of microcapsules. The thermograms showed that the thermal resistance was increased in the microencapsulated SIO, indicating that the emulsion-based system may be a way to protect the omega-3 in the SIO. In addition, the microencapsulation conferred an increased crystallinity degree, indicating a higher structural organization. Moreover, this method did not affect the stability of SIO, as confirmed by 1H NMR. The release of omega-3 acyl units from the SIO was correlated with the decrease of the methynic proton (sn, 2 position) of triacylglycerol (TAG). In contrast, the increase of 1,3-diglycerides was negatively correlated with the decrease of glyceryl groups (sn, 1,3 positions). The HGS conditions did not significantly alter the stability of the omega-3 of SIO over 180min. The SIO-Ova microcapsules had a similar behavior to the SIO, and the presence of Ova was not enough to prevent the decrease of omega-3 content over 180min. The SIO-Ova-Pec and SIO-Ova-XG microcapsules were shown to protect the omega-3 content effectively. In conclusion, the microcapsules developed in this study can be used to transport nutraceutical compounds because they are resistant to the human gastric conditions tested in vitro.

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

Doce de leite e uma sobremesa lactea concentrada (cerca de 70% de solidos) muito apreciada no Brasil. Propriedades termofisicas e reologicas de duas formulacoes de doce de leite brasileiro (puro e adicionado de coco ralado a 1,5% em massa) foram determinadas a temperaturas compreendidas entre 28,4 e 76,4 °C. No geral, a presenca de flocos de coco nao acarretou diferencas significativas (p < 0,05) nestas propriedades das duas formulacoes. A capacidade calorifica variou entre (2633,2 e 3101,8) J/kg.°C; a condutividade termica entre (0,383 e 0,452) W/m°C; a massa especifica entre (1350,7 e 1310,7) kg/m3; e enfim, a difusividade termica entre (1,082 × 10-7 e 1,130 × 10-7) m2/s. O modelo de Bingham descreveu adequadamente o comportamento nao Newtoniano dos dois produtos, com tensao critica de escoamento variando entre (27,3 e 17,6) Pa e a viscosidade plastica de (19,9 a 5,9) Pa.s.

Heteroprotein complex coacervates of ovalbumin and lysozyme: Formation and thermodynamic characterization

The formation of heteroprotein coacervates obtained by the interaction of ovalbumin (Ova) and lysozyme (Lys) was investigated using turbidimetric analysis and the zeta potential at different protein ratios, pH values and concentrations of NaCl. The complexes were formed over a wide pH range with a 1:1 (Ova:Lys) ratio and the highest turbidity was observed at pH 7.5, which optimal biopolymer interactions occurring. The addition of NaCl disfavored formation, even at low concentrations, and suppressed it at 300mM. The complex coacervate formation occurred in the region between the isoelectric points (pI) of the proteins, predominantly by electrostatic interactions but with participation of hydrogen bonds. The structures formed had an average size of ∼2μm, which was well above the isolated proteins, and microscopic analysis revealed that the complexes had a globular structure. The interaction was exothermic and spontaneous with a favorable entropic and unfavorable entropic contribution during interaction.

Complex coacervation between lysozyme and pectin: Effect of pH, salt, and biopolymer ratio

The complexation between lysozyme and pectin was studied by acidification using zeta potential, turbidity measurements and calorimetry titration. The complexes were analyzed in various NaCl concentrations with different ratios. At ratio 1:1 with 0.01M NaCl, is worth mentioning that the insoluble complexes were formed between pH 2.0 and 7.0, which represents a great range to apply this complex to different food matrices. When the ratio was increased from 1:1 to 3:1, the pH range between the pHφ1 and pHφ2 increased even more. When the NaCl concentration was increased from 0.01M to 0.2M, a progressive reduction of turbidity was observed. At 0.4M NaCl, there was total suppression of complex formation at ratio ≤ 3:1. The process of complex coacervate formation occurred in two different steps, presenting favorable enthalpic as well as entropic contributions. The positive entropy change is a strong indication that water molecules have been released from the complex surface, however the positive sign of TΔS suggests that hydrophobic interactions were involved in the interaction between lysozyme and pectin. Microscopy images of the samples revealed that the complexes presented a spheroid-like appearance which may contribute to possible future applications.

Effect of xanthan gum or pectin addition on Sacha Inchi oil-in-water emulsions stabilized by ovalbumin or tween 80: Droplet size distribution, rheological behavior and stability

The aim of this work was to studied the formation, stability and characterization of oil-in-water emulsions formed by Sacha Inchi oil (SIO) 8% (w/w) with either ovalbumin (Ova) or Tween 80 (Tw80), as emulsifiers at 0.5%-2.0% (w/w) and stabilized with pectin (Pec) at 1.0%-3.0% (w/w) or xanthan gum (XG) at 0.25%-1.0% (w/w). The emulsions were evaluated at 0, 1, 7 and 14 days after preparation and kept at a temperature of 25 ± 1 °C for the ζ-potential, particle size distribution, polydispersion, and emulsion stability index measurements. The emulsions were characterized by optical microscopy, viscosity and rheological behavior. It was observed that it is possible to form oil-in-water emulsions with SIO-Ova and Pec that are stable at 25 °C for at least 14 days with a polydispersion value between 0.2 and 0.5. However, the emulsions with SIO-Ova and XG are stable at several concentrations of XG but are more viscous and can form aggregates. The presence of a biopolymer is essential for the kinetic stability of the emulsions containing Ova as the emulsifier. For the emulsions containing Tw80, this conclusion applies only to emulsions with XG concentrations of 0.5% to 1.0%, in which the stability mechanism is distinct.

Formation and characterization of the complex coacervates obtained between lactoferrin and sodium alginate

The aim of this study was to evaluate the influence of some parameters (pH, NaCl, and ratio of biopolymers) on the formation of the complex coacervates of lactoferrin and sodium alginate. Different ratios of lactoferrin:sodium alginate were tested (1:1, 1:2, 1:4,1:8, 2:1, 4:1, and 8:1) at pH levels ranging from 2.0 to 7.0 with different concentrations of NaCl (0, 50, 100, 150, and 200 mM). Sodium alginate has a molecular weight of 138 kDa ± 0.07. The ratio of 8:1(lactoferrin: sodium alginate) at a pH of 4.0 with a low salt concentration was the optimal condition for the formation of the complex. The thermodynamic parameters demonstrated that the interaction between lactoferrin and sodium alginate was exothermic and spontaneous with a favorable enthalpic and unfavorable entropic contribution during the interaction. The chemical, thermal and morphological characteristics of the biopolymers and the complex coacervates demonstrated their nature and changes due to electrostatic interactions. The formation of complex coacervates between lactoferrrin and sodium alginate can serve as an alternative to the incorporation of lipophilic functional ingredients sensitive to high temperatures in various food systems.

Interpolymeric Complexes Formed Between Whey Proteins and Biopolymers: Delivery Systems of Bioactive Ingredients: Complexes between WPI and biopolymers…

Whey proteins are obtained from dairy industry waste. Studies involving the analysis of the bioactive compounds in whey show health benefits, as it is an excellent source of indispensable amino acids. Milk whey contains principally β-lactoglobulin, α-lactoglobulin, bovine serum albumin, and lactoferrin, proteins with innumerable functional and technological properties. One application of these proteins in food is the formation of interpolymer complexes, along with other proteins or anionic polysaccharides. The formation of complexes occurs mainly through electrostatic interactions between a negatively charged biopolymer and a positively charged biopolymer. This formation is influenced by factors such as pH, ionic strength, and biopolymer ratio. Because they do not use high temperatures and chemical reagents and have additional nutritional and functional value, these complexes have been used as encapsulating agents for bioactive ingredients. Recent studies on their training and applications are addressed in this review to boost new research and applications in the food industry, thus increasing opportunities for utilizing whey proteins.

Textural behavior of gels formed by rice starch and whey protein isolate: Concentration and crosshead velocities

Fabricated food gels involving the use of hydrocolloids are gaining polpularity as confectionery/convenience foods. Starch is commonly combined with a hydrocolloid (protein our polyssacharides), particularly in the food industry, since native starches generally do not have ideal properties for the preparation of food products. Therefore the texture studies of starch–protein mixtures could provide a new approach in producing starch-based food products, being thus acritical attribute that needs to be carefully adjusted to the consumer liking. This work investigated the texture and rheological properties of mixed gels of different concentrations of rice starch (15%, 17.5%, and 20%) and whey protein isolate (0%, 3%, and 6%) with different crosshead velocities (0.05, 5.0, and 10.0 mm/s) using a Box–Behnken experimental design. The samples were submitted to uniaxial compression tests with 80% deformation in order to determinate the following rheological parameters: Young’s modulus, fracture stress, fracture deformation, recoverable energy, and apparent biaxial elongational viscosity. Gels with a higher rice starch concentration that were submitted to higher test velocities were more rigid and resistant, while the whey protein isolate concentration had little influence on these properties. The gels showed a higher recoverable energy when the crosshead velocity was higher, and the apparent biaxial elongational viscosity was also influenced by this factor. Therefore, mixed gels exhibit different properties depending on the rice starch concentration and crosshead velocity.