Eduardo Basílio de Oliveira

Food Protein-polysaccharide Conjugates Obtained via the Maillard Reaction: A Review

The products formed by glycosylation of food proteins with carbohydrates via the Maillard reaction, also known as conjugates, are agents capable of changing and improving techno-functional characteristics of proteins. The Maillard reaction uses the covalent bond between a group of a reducing carbohydrates and an amino group of a protein. This reaction does not require additional chemicals as it occurs naturally under controlled conditions of temperature, time, pH, and moisture. Moreover, there is growing interest in modifying proteins for industrial food applications. This review analyses the current state of art of the Maillard reaction on food protein functionalities. It also discusses the influence of the Maillard reaction on the conditions and formulation of reagents that improve desirable techno-functional characteristics of food protein.

Potential Antileukemia Effect and Structural Analyses of SRPK Inhibition by N-(2-(Piperidin-1-yl)-5-(Trifluoromethyl)Phenyl)Isonicotinamide (SRPIN340).

Dysregulation of pre-mRNA splicing machinery activity has been related to the biogenesis of several diseases. The serine/arginine-rich protein kinase family (SRPKs) plays a critical role in regulating pre-mRNA splicing events through the extensive phosphorylation of splicing factors from the family of serine/arginine-rich proteins (SR proteins). Previous investigations have described the overexpression of SRPK1 and SRPK2 in leukemia and other cancer types, suggesting that they would be useful targets for developing novel antitumor strategies. Herein, we evaluated the effect of selective pharmacological SRPK inhibition by N-(2-(piperidin-1-yl)-5-(trifluoromethyl)phenyl)isonicotinamide (SRPIN340) on the viability of lymphoid and myeloid leukemia cell lines. Along with significant cytotoxic activity, the effect of treatments in regulating the phosphorylation of the SR protein family and in altering the expression of MAP2K1, MAP2K2, VEGF and FAS genes were also assessed. Furthermore, we found that pharmacological inhibition of SRPKs can trigger early and late events of apoptosis. Finally, intrinsic tryptophan fluorescence emission, molecular docking and molecular dynamics were analyzed to gain structural information on the SRPK/SRPIN340 complex. These data suggest that SRPK pharmacological inhibition should be considered as an alternative therapeutic strategy for fighting leukemias. Moreover, the obtained SRPK-ligand interaction data provide useful structural information to guide further medicinal chemistry efforts towards the development of novel drug candidates.

Recovery of casein-derived peptides with in vitro inhibitory activity of angiotensin converting enzyme (ACE) using aqueous two-phase systems

Peptides inhibiting the activity of angiotensin converting enzyme (ACE) were obtained by trypsin-catalyzed hydrolysis of bovine milk casein, performed at 37°C, during 1, 2, 5, 8 and 24h. Results of in vitro inhibitory activity ranged between 13.4% and 78.5%. The highest ACE inhibitory activity was evidenced for hydrolysates obtained after 2h of reaction. Aqueous two-phase systems (ATPS) formed by polyethylene glycol of 1500gmol-1 (PEG 1500)+sodium phosphate or potassium phosphates were produced and evaluated, in terms of partition coefficients (K) and extraction yields (y), to recovery the casein hydrolysates at room temperature. In ATPS containing sodium phosphate, the peptides showed a slightly greater affinity toward the bottom salt-rich phase (0.1≤K≤0.9; 5.7%≤y≤47%). In the case of ATPS containing potassium phosphates, these molecules showed substantially greater affinity toward the top polymer-rich phase (137≤K≤266; y≥99%). These results point out extraction using PEG 1500/potassium phosphate ATPS is an efficient technique to recover casein hydrolysates containing ACE inhibitors peptides. Outlined data will be helpful in integrating such unit operation to larger scale processes.

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.

Formation and characterization of supramolecular structures of β-lactoglobulin and lactoferrin proteins

Combination of β-lactoglobulin (β-Lg) and lactoferrin (Lf), biomacromolecules derived from bovine whey, was used in the formation of supramolecular structures by thermal gelation technique to adjust the pH. Furthermore, the influence of the molar ratio, temperature, pH, and heating time in the formation of supramolecular structures were also studied. The characterization of the protein supramolecular structures was performed using dynamic light scattering, zeta potential measurements, molecular spectrofluorimetry, and circular dichroism spectroscopy. The thermal behavior of the pure proteins was investigated by differential scanning calorimetry. The protein denaturation temperatures were of around 85°C for the β-Lg and around 52°C and 85°C (a small portion) for the Lf. The protein molar ratio of 2:1 Lf/β-Lg was used to form the structures, whose characterization showed that the best conditions of supramolecular structure formation occurred at pH6.5 and at temperatures of 62.5°C. In those conditions, more stable systems with reduced hydrophobic surface and average sizes between 30 and 100nm were generated. The correlation between pH and temperature suggests that the method of preparation of the supramolecular structure affects its size during storage.

Acacia gum as modifier of thermal stability, solubility and emulsifying properties of α-lactalbumin.

Protein-polysaccharide conjugates often display improved techno-functional properties when compared to their individual involved biomolecules. α-Lactalbumin:acacia gum (α-la:AG) conjugates were prepared via Maillard reaction by the dry-heating method. Conjugate formation was confirmed using results of absorbance, o-phthalaldehyde test, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography. Techno-functional properties (emulsifying characteristics, solubility, and thermal stability) were evaluated for α-la, α-la/AG mixtures and α-la:AG conjugates. Conjugate thermal stability was improved compared to pure α-la treated at the same conditions of conjugate formation. Response surface methodology was used to establish models to predict solubility and emulsifying activity as functions of the salt concentration, pH and reaction time. α-la:AG conjugate solubility is affected in a complex manner by the three factors analyzed. Emulsifying activity index (EAI) of α-la is significantly affected by pH, while the α-la:AG EAI is affected by the three analyzed factors. Both solubility and EAI are maximized with pH 8.0, NaCl concentration of 0.3 mol L(-1) and two days of Maillard reaction.

Engineered GH11 xylanases from Orpinomyces sp. PC-2 improve techno-functional properties of bread dough: GH11 xylanases improve bread dough

BACKGROUND Endo-1,4-β-xylanases have marked hydrolytic activity towards arabinoxylans. Xylanases (xynA) produced by the anaerobic fungus Orpinomyces sp. strain PC-2 have been shown to be superior in specific activity, which strongly suggests their applicability in the bakery industry for the processing of whole-wheat flour containing xylans. In the present study, two xylanases from this source, the small wild-type xylanase SWT and the small mutant xylanase SM2 (V108A, A199T), were expressed in Escherichia coli, purified, characterized, tested for their ability to hydrolyze whole-wheat flour and applied in dough processing. RESULTS Both purified SM2 and SWT showed high specific activity against oat spelt xylan and wheat arabinoxylan, exhibiting maximum activity at pH 3-7 and 60 °C. SM2 was more thermostable than SWT, which suggests that the mutations enhanced its stability. Both SWT and SM2 were able to hydrolyze whole-wheat flour, and evaluation of their applicability in dough processing by the sponge method indicated that use of these enzymes increased dough volume by 60% and reduced texture hardness by more than 50%, while gumminess and chewiness were reduced by 40%. CONCLUSION The recombinant xylanases showed potential for application in bakery processing and can improve techno-functional properties in sponges.

Camu-camu (Myrciaria dubia) from commercial cultivation has higher levels of bioactive compounds than native cultivation (Amazon Forest) and presents antimutagenic effects in vivo : Commercial camu-camu as functional food

BACKGROUND Camu-camu (Myrciaria dubia) is a typical Amazonian fruit and has high antioxidant capacity due to its high levels of vitamin C and phenolic compounds. This study aimed to determine the phytochemicals, antioxidant capacity and antimutagenic effects of camu-camu fruits with different maturity stages grown in dry (commercial cultivation) or flooded environments (native cultivation, Amazon). RESULTS Total polyphenols, ascorbic acid and in vitro antioxidant capacity levels were higher in ripe fruits grown in a commercial cultivation. The extracts from ripe camu-camu grown in a commercial cultivation exerted antioxidant effects and high percentage of protection against doxorubicin and 1,2-dimethylhydrazine in all tested systems (liver, bone marrow and gut), for three camu-camu extract concentrations (17, 85 and 170 mg kg-1 body weight), as follows: bone marrow minocronucleus (37.91%, 41.75%, 43.95%); micronucleus gut test (61.01%, 64.40%, 50.28%); apoptosis index (60.26%, 62.44%, 58.22%); comet assay through the tail moment (71.64%, 72.31%, 70.70%), percent DNA in the tail (64.54%, 68.75%, 76.79%) and tail intensity (76.43%, 81.02%, 68.33%). CONCLUSION The results of this study contribute to increasing the production of camu-camu fruits grown in dry environments and their use as a health-promoting food.

Increased thermal stability of anthocyanins at pH 4.0 by guar gum in aqueous dispersions and in double emulsions W/O/W

This study investigated the potential of guar gum and a double emulsion to increase the thermal stability of anthocyanins. The effect of different guar gum concentrations (0%, 0.25%, 0.50%, 0.75%, 1%, 1.25%, 1.5% and 1.75%) was evaluated in relation to color stability, concentration of anthocyanins and antioxidant capacity under storage for 10 days at 40 °C in the presence of light. The addition of guar gum (0.75-1.75%) significantly increased the color stability and bathochromic displacement of the samples, suggesting the occurrence of a co-pigmentation process. The total anthocyanin content was to 41% after storage in treatments without guar gum, but when using 1.25% guar gum the final concentration was 70% and there was a 2.4 fold increase in the half-life time of anthocyanins. A significant effect of guar gum addition on the antioxidant capacity of the samples was observed. In the second step, the anthocyanins were added together with 1.25% guar gum in the internal aqueous phase of the double emulsion and stored for 10 days at 40 °C in the presence of light. The double emulsion presented high encapsulation efficiency (90.6%) and high kinetic stability under the conditions evaluated, in addition to protecting anthocyanin molecules against degradation.

Optimization of pectin extraction from Ubá mango peel through surface response methodology

A central composite design was used to determine effects of pH (1.16-2.84), extraction temperature (63-97°C) and time (35-85min) on the yield, degree of degree of esterification (DE) and viscosity of pectins extracted. For pectin extraction, the previously sanitized mango shells were dried and crushed to obtain the flour that was treated with an ethanol solution obtaining the alcohol insoluble residue (AIR). Subsequently, the AIR was mixed in ethanol with the extraction solution of hydrochloric acid. Pectin yields ranged from 18.8 to 32.1g/100g of AIR, whereas the degree of esterification (DE) and viscosity values ranged from 62.2 to 86.2% and from 1.58 to 45.85mPa·s, respectively. An inverse correlation was found between extraction yield and viscosity. Relying upon the desirability function, two optimum conditions were determined: 35min<t<48min; 85.4°C<T<97°C; 1.66<pH<2.4 and 80min<t<85min; 94.3°C<T<97°C; 1.66<pH<1.79. Under these conditions, yields >30% from the AIR, DE≥70.0% and η≥20.0mPa·s.