Síntesis de glicoconjugados de albúmina sérica bovina y oligosacáridos de quitosano para el análisis de adhesión bacteriana / Synthesis of glycoconjugates of bovine albumin and chitosan oligosaccharides for the analysis of bacterial adhesion / Síntese de glicoconjugados de albumina serica bovina e oligossacarídeos de quitosana para análise de adesão bacteriana

Resumen El aumento de la resistencia a los antibióticos por parte de bacterias patógenas ha motivado la búsqueda de alternativas para disminuir su utilización. Dentro de las opciones propuestas se encuentra la terapia de antiadherencia, en la cual se utilizan moléculas análogas a los glicoepítopes que son reconocidos por las bacterias para impedir la unión de éstas al tejido celular. En este estudio se llevó a cabo la obtención de glicoconjugados por medio de la reacción de Maillard partiendo de albúmina sérica bovina (BSA) y oligosacáridos de quitosano (oligosacáridos sin ultrafiltrar, ultrafiltrados y ultrafiltrados acetilados), en proporción 1:1 (p/p) a tres temperaturas de incubación (50, 60 y 70 °C) por 30 min. La caracterización de los conjugados sintetizados se realizó utilizando electroforesis (SDS-PAGE), espectroscopía de infrarrojo y espectroscopía de fluorescencia. Se realizaron ensayos de reconocimiento usando aglutinina de germen de trigo (WGA) y bacterias [Escherichia coli (K88ac y K88+)]. La caracterización por medio de electroforesis y espectroscopía de infrarrojo evidenció la unión de los oligosacáridos de quitosano a la estructura de la BSA. Además, los ensayos evidenciaron el reconocimiento de las moléculas sintetizadas tanto por la lectina WGA como por las bacterias. Los glicoconjugados sintetizados sin ultrafiltrar ni acetilar mostraron resultados muy favorables en el reconocimiento por ambas bacterias, lo que constituye una ventaja práctica, ya que su implementación a mayor escala reduciría costos de producción

Abstract The increase in antibiotic resistance by pathogenic bacteria has motivated the search for alternatives to reduce the use of antibiotics. Among these alternatives is anti-adhesion therapy, in which molecules that mimic the glycoepitopes that recognise bacteria are used to prevent their binding to cellular tissue. In this study, glycoconjugates were obtained by means of the Maillard reaction starting from bovine serum albumin (BSA) and chitosan oligosaccharides (unfiltered oligosaccharides, ultrafiltered and acetylated ultrafiltered), in a ratio of 1:1 (w/w) at three incubation temperatures (50, 60 and 70 °C) per 30 min. The characterisation was performed using the techniques of electrophoresis (SDS-PAGE), infrared spectroscopy and fluorescence spectroscopy. Recognition assays were performed using wheat germ agglutinin (WGA) and Escherichia coli bacteria (K88ac and K88+). Characterisation by electrophoresis and infrared spectroscopy demonstrated the binding of chitosan oligosaccharides to the structure of BSA. In addition, the tests showed the recognition of the molecules synthesised by both the WGA lectin and the E. coli bacteria. The glycoconjugates synthesised without ultrafiltration or acetylation showed very favourable results in recognition with both bacteria, which is an advantage, since its implementation on a larger scale would reduce production costs.

Resumo O aumento da resistência aos antibióticos por bactérias patogênicas tem motivado a busca de alterna­tivas para reduzir seu uso. Entre essas alternativas está a terapia anti-adesão, na qual são utilizadas moléculas análogas aos glicoepítopos que são reconhecidas pelas bactérias para impedir sua união ao tecido celular. Neste estudo, os glicoconjugados foram obtidos por meio da reação de Maillard a partir de albumina sérica bovina (BSA) e oligossacarídeos de quitosana (oligossacarídeos não ultra­filtrados, ultrafiltrados e acetilados ultrafiltrados), na proporção de 1:1 (p/p) em três temperaturas de incubação (50, 60 e 70 °C) durante 30 min. A caracterização dos conjugados sintetizados foi realizada utilizando a eletroforese (SDS-PAGE), espectroscopia de infravermelho e espectroscopia de fluorescência. Os ensaios de reconhecimento foram realizados utilizando aglutinina de germe de trigo (WGA) e bactérias [Escherichia coli (K88ac e K88+)]. A caracterização por meio de eletroforese e espectroscopia de infravermelho demonstrou a união dos oligossacarídeos de quitosana à estrutura da BSA. Além disso, os testes evidenciaram o reconhecimento das moléculas sintetizadas tanto pela lectina WGA quanto pelas bactérias. Os glicoconjugados sintetizados sem ultrafiltração ou acetilação apresentaram resultados muito favoráveis no reconhecimento por ambas as bactérias, o que é uma vantagem, visto que sua implementação em maior escala reduziria custos de produção.

Anthocyanins and Functional Compounds Change in a Third-Generation Snacks Prepared Using Extruded Blue Maize, Black Bean, and Chard: An Optimization.

The effect of extrusion cooking on bioactive compounds in third-generation snacks (TGSE) and microwave-expanded snacks (MWSE) prepared using black bean, blue maize, and chard (FBCS) was evaluated. FBCS was extruded at different moisture contents (MC; 22.2-35.7%), extrusion temperatures (ET; 102-142 °C), and screw speeds (SP; 96-171 rpm). Total anthocyanin content (TAC), contents of individual anthocyanins, viz., cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside, pelargonidin-3-5-diglucoside, and delphinidin-3-glucoside chloride, total phenolic content (TPC), antioxidant activity (AA), and color parameters were determined. TAC and individual anthocyanin levels increased with the reduction in ET. ET and MC affected the chemical and color properties; increase in ET caused a significant reduction in TPC and AA. Microwave expansion reduced anthocyanin content and AA, and increased TPC. Extrusion under optimal conditions (29% MC, 111 rpm, and 120 °C) generated products with a high retention of functional compounds, with high TAC (41.81%) and TPC (28.23%). Experimental validation of optimized process parameters yielded an average error of 13.73% from the predicted contents of individual anthocyanins. Results suggest that the TGSE of FBCS obtained by combining extrusion and microwave expansion achieved significant retention of bioactive compounds having potential physiological benefits for humans.

Physicochemical, Rheological, and Morphological Characteristics of Products from Traditional and Extrusion Nixtamalization Processes and Their Relation to Starch.

The aim of this study was to compare the physicochemical, rheological, and morphological characteristics of corn, nixtamalized flour, masa, and tortillas from the traditional nixtamalization process (TNP) and the extrusion nixtamalization process (ENP) and their relationship with starch. The traditional and extrusion processes were carried out using the same variety of corn. From both processes, samples of ground corn, nixtamalized flour, masa, and tortillas were obtained. The extrusion process produced corn flour with particle sizes smaller (particle size index, PSI = 51) than that of flour produced by the traditional nixtamalization process (PSI = 44). Masa from the TNP showed higher modulus of elasticity (G') and viscosity (G ″) values than that off masa from the ENP. Furthermore, in a temperature sweep test, masa from the TNP showed a peak in G' and G ″, while the masa from the ENP did not display these peaks. The ENP-produced tortillas had higher resistant starch contents and comparable firmness and rollability to those from the TNP but lower quality parameter values. A comparison of the products' physicochemical properties obtained by the two processes shows the importance of controlling the damage to starch during the milling and extrusion processes to obtain tortillas of better quality. For the first time, we propose the measurement of the viscoelastic parameters G' and G ″ in temperature sweep mode to monitor changes in the degree of starch damage.

Effect of Extrusion Processing Conditions on the Phenolic Compound Content and Antioxidant Capacity of Sorghum (Sorghum bicolor (L.) Moench) Bran.

Sorghum is a cereal with little use in human diet; however, this grain can provide several nutrients and, additionally, has a high content of phenolic compounds concentrated in bran, which could be beneficial to human health due to its high antioxidant capacity. However, these bioactive compounds are bound within the cell wall matrix; it is necessary to release these compounds to take advantage of their antioxidant properties. The extrusion process increases the accessibility of bound phenolic compounds, breaking their bonds from the bran matrix. The aim of this study was to determine the optimal extrusion conditions for maximizing the phenolic compound content and antioxidant capacity of sorghum bran extrudate. The extrusion process factors evaluated were feed moisture (FM) from 25 to 35% and the fourth extrusion zone temperature (T) in the range of 140-180 °C. Analysis of variance and response surface analysis were used in the evaluation. The prediction coefficient, (FM)2, (T)2 and their interaction (FM)(T) significantly affected the free total phenolic compounds. The antioxidant capacity of the free total phenolic compounds was significantly affected by (FM)2 and (T)2. The optimal extrusion conditions were FM = 30% and T = 160 °C, which provided free total phenolic compounds with a value of 7428.95 µg GAE/g (predicted value: 7810.90 µg GAE/g) and antioxidant capacity with a value of 14.12 µmol TE/g (predicted value: 14.85 µmol TE/g). Results confirmed that extrusion process optimization was useful to increase the content of phenolic compounds and improved the antioxidant capacity of sorghum bran.

Effect of Extrusion Conditions and the Optimization of Phenolic Compound Content and Antioxidant Activity of Wheat Bran Using Response Surface Methodology.

The extrusion process (EP) consists of heat and mechanical treatments under different conditions of moisture, shear, and pressure and rapidly causes structural alterations and changes in the functional properties of the extruded material. The aim of this study was to evaluate the effect of extrusion conditions and optimize the wheat bran extrusion conditions to achieve the greatest content of phenolic compounds and antioxidant activity using response surface methodology. The EP factors evaluated were feed moisture (FM) (25-33.54%) and final extrusion temperature (T) (140-180 °C). The properties evaluated in the extruded material were bound total phenol content (BTPC), total phenolic compounds and antioxidant activity (AOX). Analysis of variance (ANOVA) and response surface methodology were used in the evaluation. The determination coefficients, (FM)2 and (T)2, very significantly affected the BTPC and bound 2,2-diphenyl-1-picrylhydrazyl content (BDPPHC). The optimization was performed by overlaying two contour plots to predict the best combination regions. The optimized extrusion conditions were the following: FM = 30% and T = 140 °C, which provided BTPC = 3547.01 µgGAE/g (predicted: 3589.3 µgGAE/g) and BDPPHC = 9.5 µmolTE/g (predicted: 10.4 µmolTE/g); and FM = 30% and T = 180 °C, which provided BTPC = 3342.3 µgGAE/g (predicted: 3727.7 µgGAE/g) and BDPPHC = 9.5 µmolTE/g (predicted: 9.3 µmolTE/g). The EP increased the phenolic compounds and AOX, and enhancement of these properties in wheat bran products could make them functional foods.

Management of freezing rate and trehalose concentration to improve frozen dough properties and bread quality

Abstract Bread is one of the most consumed foods in the world, and alternatives have been sought to extend its shell life, and freezing is one of the most popular methods. The purpose of this study was to evaluate the effect of freezing rate and trehalose concentration on the fermentative and viscoelastic properties of dough and bread quality. Dough was prepared and trehalose was added at three concentrations (0, 400, 800 ppm); dough was pre fermented and frozen at two freezing rates then stored for 42 days. Frozen dough samples were thawed every two weeks. CO2 production and elastic and viscous modulus were determined. In addition, bread was elaborated and specific volume and firmness were evaluated. High trehalose concentrations (400 and 800 ppm) produced dough with the best viscoelastic and fermentative properties. Greater bread volume and less firmness were observed when a slow freezing rate (-.14 °C/min) was employed.

Micro- and nanoparticles by electrospray: advances and applications in foods.

Micro- and nanotechnology are tools being used strongly in the area of food technology. The electrospray technique is booming because of its importance in developing micro- and nanoparticles containing an active ingredient as bioactive compounds, enhancing molecules of flavors, odors, and packaging coatings, and developing polymers that are obtained from food (proteins, carbohydrates), as chitosan, alginate, gelatin, agar, starch, or gluten. The electrospray technique compared to conventional techniques such as nanoprecipitation, emulsion-diffusion, double-emulsification, and layer by layer provides greater advantages to develop micro- and nanoparticles because it is simple, low cost, uses a low amount of solvents, and products are obtained in one step. This technique could also be applied in the agrifood sector for the preparation of controlled and/or prolonged release systems of fertilizer or agrochemicals, for which more research must be conducted.

Obtaining ready-to-eat blue corn expanded snacks with anthocyanins using an extrusion process and response surface methodology.

Extrusion is an alternative technology for the production of nixtamalized products. The aim of this study was to obtain an expanded nixtamalized snack with whole blue corn and using the extrusion process, to preserve the highest possible total anthocyanin content, intense blue/purple coloration (color b) and the highest expansion index. A central composite experimental design was used. The extrusion process factors were: feed moisture (FM, 15%-23%), calcium hydroxide concentration (CHC, 0%-0.25%) and final extruder temperature (T, 110-150 °C). The chemical and physical properties evaluated in the extrudates were moisture content (MC, %), total anthocyanins (TA, mg·kg(-1)), pH, color (L, a, b) and expansion index (EI). ANOVA and surface response methodology were applied to evaluate the effects of the extrusion factors. FM and T significantly affected the response variables. An optimization step was performed by overlaying three contour plots to predict the best combination region. The extrudates were obtained under the following optimum factors: FM (%) = 16.94, CHC (%) = 0.095 and T (°C) = 141.89. The predicted extrusion processing factors were highly accurate, yielding an expanded nixtamalized snack with 158.87 mg·kg(-1) TA (estimated: 160 mg·kg(-1)), an EI of 3.19 (estimated: 2.66), and color parameter b of -0.44 (estimated: 0.10).

Estimated glycemic index and dietary fiber content of cookies elaborated with extruded wheat bran.

The increasing demand for high-fiber products has favored the design of numerous bakery products rich in fiber such as bread, cookies, and cakes. The objective of this study was to evaluate the dietary fiber and estimated glycemic index of cookies containing extruded wheat bran. Wheat bran was subjected to extrusion process under three temperature profiles: TP1;(60, 75, 85 and 100 °C), TP2;(60, 80, 100 and 120 °C), and TP3;(60, 80, 110 and 140 °C) and three moisture contents: (15, 23, and 31 %). Cookies were elaborated using extruded wheat bran (30 %), separated into two fractions (coarse and fine). The dietary fiber content of cookies elaborated with extruded wheat bran was higher than the controls; C0 (100 % wheat flour) and C1 (30 % of no extruded bran coarse fraction) and C2 (30 % of no extruded bran fine fraction). The higher values of dietary fiber were observed on cookies from treatments 5 (TP1, 31 % moisture content and coarse fraction) and 11 (TP2, 31 % moisture content and coarse fraction). The estimated glycemic index of cookies ranged from 68.54 to 80.16. The dietary fiber content of cookies was increased and the lowest glycemic index corresponded to the cookies elaborated with extruded wheat bran. Cookie made with the treatment 11 had a better dietary fiber content and lower estimated glycemic index.

Preparation and characterization of durum wheat (Triticum durum) straw cellulose nanofibers by electrospinning.

Cellulose nanofibers from durum wheat straw ( Triticum durum ) were produced and characterized to study their potential as reinforcement fibers in biocomposites. Cellulose was isolated from wheat straw by chemical treatment. Nanofibers were produced via an electrospinning method using trifluoroacetic acid (TFA) as the solvent. The nanofibers were 270 ± 97 nm in diameter. Analysis of the FT-IR spectra demonstrated that the chemical treatment of the wheat straw removed hemicellulose and lignin. XRD revealed that the crystallinity of the cellulose was reduced after electrospinning, but nanofibers remained highly crystalline. The glass transition temperature (T(g) value) of the fibers was 130 °C, higher than that of cellulose (122 °C), and the degradation temperature of the fibers was 236 °C. Residual TFA was not present in the nanofibers as assessed by the FT-IR technique.