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

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.

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.

Abstract In the baking industry, different processes and methods of freezing have been used for breadmaking to preserve a quality comparable to that of fresh bread. In this study, the effect of part-baking time, freezing rate, and frozen storage time on part-baked French bread quality was determined. The bread was part-baked for 0, 3 and 6 min, frozen at slow (0.15 °C/min) and fast (1.75 °C/min) freezing rates, stored under freezing conditions for up to 56 days and thawed every 14 days. Part-baked bread was rebaked, and the SV and firmness at 2, 24 and 48 h were obtained. An experiment with a factorial design of 3×2×5 (3 part-baking time, 2 freezing rates and 5 frozen storage times) with analysis of variance (ANOVA) at a confidence level of 95% was carried out. The highest SV was obtained at 6 min of part-baking at a slow freezing rate and decreased as the frozen storage time increased. In contrast, TPA showed that bread firmness increases when the specific volume decreases, and the highest firmness is at 0 min of part-baked time. Relatively long part-baking times allow for firm crumb formation with limited damage to the structure and therefore bread with optimal quality.

Abstract The study aims to investigate the effects of mixing on the protein solubility and secondary structure in corn dough during processing for tortilla production. To evaluate how mixing affects dough rheology, the storage moduli (G´), loss moduli (G´´) and tangent of the phase angle (Tan δ) dependent on frequency and texture profile analysis (TPA) were determined. HPLC-SEC showed an increased proportion of soluble polymeric proteins (soluble high molecular weight species). FT-IR results revealed that mixing promotes an increase of the β-sheet structure and a reduction of α-helix proportion, which suggests protein aggregation. Rheological data showed that the elastic prevailed over the viscous behavior (G´ > G´´) in the corn dough, with a soft solid material and an ordered and stable structure. Mixing, an intermediate step for dough production had important effects in protein structure and dough rheological properties. The increased Tan δ ( G´´/ G´) is consistent with an increased viscous character and polymers aggregation that was demonstrated in this case for proteins.

Resumen El estudio tiene como objetivo investigar los efectos del mezclado sobre la solubilidad de las proteínas del maiz y su estructura secundaria, en masas de maíz durante el procesamiento para la producción de tortillas. Para evaluar cómo el mezclado afecta la reología de la masa, se determinaron los módulos de almacenamiento (G´), los módulos de pérdida (G´´) y el ángulo de fase (Tan δ) dependientes de la frecuencia y el perfil de textura (TPA). Los análisis cromatográficos (HPLC-SEC) mostraron una mayor proporción de proteínas poliméricas solubles (especies solubles de peso molecular alto). Los resultados de FT-IR revelaron que la mezcla promueve el aumento de la estructura de la hoja β y la reducción de la proporción de la hélice α, lo que sugiere la agregación de las proteínas. Los datos reológicos mostraron que en las masas de maíz prevaleció el comportamiento elástico sobre el viscoso (G´ > G´´), un material sólido, blando con una estructura ordenada y estable. El mezclado, un paso intermedio para la producción de masa, tuvo efectos importantes en la estructura de la proteína y las propiedades reológicas de la masa, el aumento de Tan δ es consistente con un mayor carácter viscoso y agregación de polímeros que se demostró en este caso para las proteínas.

Abstract Oat flour was heat treated at 80, 100 or 130 °C for 30 min, then used to replace 10 or 20 % wheat flour in bread-making process. Water retention capacity, viscosity profile, specific volume, and texture profile analysis were determined at 0, 2 and 7 days after bread-making. Viscosity parameters were affected by the two levels of oat flour substitution and heat treatment. When using oat flour treated at 100 °C and substitution level of 10 and 20 %, the specific volume of bread increased (2.64 and 2.75 cm3/g). The texture profile was also affected by the level of substitution and heat treatment at 7 days of storage, the firmness of the bread decreased when 10 % of oat flour treated at 130 °C (12.86 N) was used in comparison to that made with wheat flour (19.63 N). Heat treatments in oat flour used to replace wheat flour can be an important alternative to improve the quality of bread-making products.

Resumen La harina de avena fue tratada térmicamente a 80, 100 y 130 °C durante 30 min para después ser utilizada en sustitución del 10 y 20 % de harina de trigo para la elaboración de pan. Se determinó capacidad de retención de agua, perfil de viscosidad, volumen específico y análisis de perfil de textura a los 0, 2 y 7 días de elaborado el pan. Los parámetros de viscosidad fueron afectados por los dos niveles de sustitución de harina de avena y el tratamiento térmico. Al utilizar harina de avena tratada a 100 °C a 10 y 20 % de sustitución, el volumen específico de pan aumentó (2.64 y 2.75 cm3/g). El perfil de textura, también se vio afectado por el nivel de sustitución y el tratamiento térmico a los 7 días de almacenamiento, la firmeza del pan disminuyó cuando se usó 10 % de harina de avena tratada a 130 °C (12.86 N) en comparación al elaborado con harina de trigo (19.63 N). Los tratamientos térmicos en harina de avena empleada para sustituir la harina de trigo pueden ser una alternativa importante para mejorar la calidad en productos de panificación.

Abstract Sorghum bran has a high antioxidant capacity due to the high concentrations of phenolic compounds. During decortication of the sorghum grain to obtain the bran, lipid oxidation reactions may occur that cause deterioration in its quality. To avoid this, thermal stabilization processes such as extrusion are used. The objective of this work was to evaluate chemical, stability of phenolic compounds and antioxidant capacity changes of extruded red sorghum bran. Raw sorghum bran (SC) and extruded (SE) sorghum bran were stored for 42 days and chemical (peroxide index, pH, free fatty acid), phenolic compounds, antioxidant capacity and phenolic acids determinations were carried out. The type of bran was the factor that most affected results of the chemical evaluations. The SE showed greater stability in quality than the SC, which had significant changes in free fatty acid and peroxide index. The content of phenolic compounds and the antioxidant capacity of both types of bran were not modified by the effect of storage. However, the SE presented higher levels of both parameters than the SC. The sorghum bran extrusion process retards enzymatic oxidation of lipids and improves the extraction of phenolic compounds.

Resumen El salvado de sorgo posee una alta capacidad antioxidante debido a su elevado contenido de compuestos fenólicos. Durante el decorticado del grano para la obtención del salvado, pueden presentarse reacciones de oxidación lipídica que deterioran su calidad. Para evitar esto, se emplean procesos de estabilización como la extrusión. El objetivo de este trabajo fue evaluar los cambios químicos en los compuestos fenólicos y la capacidad antioxidante del salvado de sorgo rojo extrudido. Los salvados de sorgo crudo (SC) y extrudido (SE) se almacenaron durante 42 días para poder evaluar los cambios químicos (índice de peróxidos, pH y ácidos grasos libres), en los compuestos fenólicos, su capacidad antioxidante y la presencia de ácidos fenólicos. El tipo de salvado fue el factor que más afectó los resultados de las evaluaciones químicas. La calidad del SE fue más estable en comparación con la del SC, el cual tuvo cambios significativos de ácidos grasos libres e índice de peróxidos. El contenido de compuestos fenólicos y la capacidad antioxidante de ambos tipos de salvado no se modificaron significativamente (p > 0.05) por efecto del tiempo de almacenamiento, sin embargo, el SE presentó niveles superiores en compuestos fenólicos y capacidad antioxidante que el SC. El proceso de extrusión del salvado de sorgo retarda la oxidación enzimática y mejora la extracción de los compuestos fenólicos.

Abstract The objective of this work was to evaluate the effect of replacing wheat flour (HT) with oat fiber flour (HFA) with different particle size on the rheological, textural and baking properties. The particle size obtained after grinding oat fiber was 250 and 177 µm (microns). The replacement percentages used were 10, 20 or 30%. Flour mixtures were determined color, water retention capacity (CRA) and viscosity profile. The dough was measured for strength and extensibility by the Kieffer test, while the bread was measured for specific volume, water activity and texture profile. The results showed increases in force in the dough when the two fractions of HFA (250 or 177 µm) were used in the substitution of HT with respect to that obtained from HT (0.25 N). In extensibility, the most important increases were observed when 177 µm HFA was used. The specific bread volume was favored when 10 or 20% of HFA (177 µm) was used, observing very similar values between them (4.54 and 4.56 cm3 g-1, respectively), without showing significant differences to that obtained from HT (4.57 cm3 g-1). The texture profile showed the obtaining of softer breads when HFA (177 µm) was used, in its three different replacement percentages (4.86, 4.71 and 7.05 N), even improved as measured in HT (7.84 N).

Resumen El objetivo de este trabajo fue evaluar el efecto de la sustitución de harina de trigo (HT) con harina de fibra de avena (HFA) con diferente tamaño de partícula sobre las propiedades reológicas, texturales y de panificación. El tamaño de partícula obtenido después de la molienda de la fibra de avena fue de 250 y 177 µm (micrones). Los porcentajes de sustitución utilizados fueron de 10, 20 ó 30%. A las mezclas de harinas se les determinó color, capacidad de retención de agua (CRA) y perfil de viscosidad. A las masas se les midió fuerza y extensibilidad por la prueba de Kieffer, mientras que al pan se le midió volumen específico, actividad de agua y perfil de textura. Los resultados mostraron incrementos de fuerza en la masa cuando se utilizaron las dos fracciones de HFA (250 o 177 µm) en la sustitución de HT con respeto a la obtenida de HT (0.25 N). En extensibilidad, los incrementos más importantes fueron observados cuando se utilizó HFA de 177 µm. El volumen específico del pan se vio favorecido cuando se utilizó 10 o 20% de HFA (177 µm) observándose valores muy parecidos entre ellos (4.54 y 4.56 cm3 g-1, respectivamente), sin mostrar diferencias significativas al obtenido de HT (4.57 cm3 g-1). El perfil de textura mostró la obtención de panes más blandos cuando se utilizó HFA (177 µm), en sus tres diferentes porcentajes de sustitución (4.86, 4.71 y 7.05 N), incluso mejoró al medido en HT (7.84 N).

Abstract The protein present in wheat flour plays a very important role in the functionality and quality of the baking products. It is important to know how this grain component segregates in the different streams of the wheat roller milling. We analyzed twenty-three wheat (T. aestivum) flours from a commercial milling system by SDS-PAGE, to identify differences in protein components such as glutenin subunits and gliadin subclasses; finding differences in the composition of omega gliadins. Total protein (PT) and insoluble polymeric protein (PPI) were quantified by a nitrogen analyzer, with a variation of results of 11.56 to 18.41 % (db) and 5.32 to 10.54 %(db). High performance molecular exclusion liquid chro-matography (SE-HPLC) produced information of the soluble polymeric proteins (PPS), gliadins, albumins and globulins fractions, observing qualitative and quantitative differences. Flour functionality was analyzed with the rapid sedimenta-tion test, obtaining values of 4.9 to 41 mL. The difference in protein quality in the flours of the streams was demonstra-ted. Differences in quantity were in part confirmatory results. However, differences in quality, especially those related to omega gliadins is a contribution to the knowledge of this work.

Resumen Las proteínas en la harina de trigo juegan un papel muy importante en la funcionalidad y calidad de sus productos, por lo que es importante conocer como se segregan en las diferentes corrientes de la molienda de rodillos. Se analizaron 23 corrientes de harinas de trigo (T. aestivum) de un sistema de molienda comercial. Se utilizó SDS-PAGE para estudiar a las subunidades de gluteninas y las subclases de gliadinas, encontrándose diferencias en la composición de las gliadinas omega. Se cuantificaron la proteína total (PT) y proteína polimérica insoluble (PPI), encontrándose variación de 11.56 a 18.41 % (bs) y 5.32 a 10.54 % (bs). Se usó (SE-HPLC) para estudiar las fracciones: proteína polimérica soluble (PPS), gliadinas, albuminas y globulinas, observándose diferencias en el patrón de separación y en la cantidad presente en las harinas. Además, se analizó la funcionalidad de las harinas con la prueba de sedimentación, obteniendo valores de 4.9 a 41 mL. Las diferencias en cantidades encontradas son en parte información confirmatoria; sin embargo, diferencias en composición, especialmente la relacionada con Gliadinas omega gliadinas son contribución del presente trabajo.

Abstract Different studies on obtaining protein concentrates or surimi from giant squid ( Dosidicus gigas) have reported that soft gels are obtained in comparison with other fish species. Therefore, the aim of this research was to investigate the effect of the setting (30 and 60 °C, for 0, 30, 60, and 90 min) on the gelling capacity as a possible alternative to improve the textural characteristics of the gels. Treatments at 60 °C (G4, G5, and G6) had a higher percentage of insoluble protein, while the electrophoretic profile showed the presence of high molecular weight (HMW) aggregates, as well as the decrease of myosin, paramyosin and actin bands as the incubation time was increased. Likewise, these systems presented a lower content of total sulfhydryl (TSH), which is attributed to the formation of disulfide bridges. The texture profile analysis (TPA) showed that the setting application affected the different parameters evaluated (strength, elasticity, and cohesiveness). Setting as pretreatment did not prove to be a good alternative for the gelling of proteins from giant squid mantle, since the control treatment (no setting) was that which exhibited better textural characteristics.

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.

AbstractEffects of different β-glucan concentrations in maize flour on the properties of frozen maize tortillas were evaluated. Masa (dough), pre-cooked (PTs), frozen (FTs), thawed (TTs), and cooked tortillas (CTs) were made and analyzed. Moisture content of masa and tortillas significantly decreased as β-glucan concentration increased; however, the water absorption capacity (WAC), ice melting enthalpy, and frozen water in FTs increased. Texture and color of the masa, PTs, and CTs as well as sensory analysis showed differences only between tortillas with 0% and 4% β-glucans. β-glucans did not affect the texture of CTs. Soluble fiber increased by over threefold and fivefold in tortillas with 2% and 4% β-glucans, respectively, than in those without β-glucans. This result was consistent with the observed structural changes in tortillas, showing an increase in high-fiber aggregates with increasing β-glucan concentration. Tortillas with 2% β-glucans showed acceptable physicochemical, functional, and sensory properties, but over three times the soluble fiber. Therefore, it is possible to obtain frozen tortillas with high fiber content and increase their shelf life for subsequent cooking while maintaining good properties.

The purpose of this review is to compile available knowledge on content and anthocyanin type in different pigmented maize (Zea mays L.) varieties. Additionally, the effects of traditional nixtamalization processing on these compounds are listed, and the studies performed to reduce the negative effects of traditional nixtamalization are described. The use of pigmented maize varieties has increased due to their high phenolic compound content, mainly anthocyanins. These compounds are responsible for the blue-red color in plants like maize, and they have antioxidant capacity. Anthocyanins are contained in the aleurone layer at the endosperm and in the pericarp of corn kernels. The non-acyl type anthocyanins, such as cyanidin 3-glucoside, pelargonidin 3-glu-coside and peonidin 3-glucoside are the most abundant compounds in colored maize; they have high antioxidant capacity. Generally, maize varieties with blue, purple and black color kernels contain the highest anthocyanin contents. Traditional nixtamalization processing is highly aggressive for anthocyanins in maize; it causes anthocyanin losses of up to 100 % during traditional nixtamalization. However, alternative processes of nixtamalization, such as lime-cooking extrusion and fractionated nixtamalization can have higher anthocyanin and phenolic content retention. These newer nixtamalization processes can be more efficient than traditional nixtamalization. Nonetheless, more research is needed to further reduce losses of these natural compounds, which are useful for obtaining new nutraceutical products from pigmented maize varieties.

El objetivo de esta revisión es compilar el conocimiento disponible acerca del contenido y los tipos de antocianinas identificadas en diferentes variedades de maíces (Zea mays L.) pigmentados. Principalmente, se pretende identificar el efecto en estos compuestos causado por la nixtamalización tradicional, y especificar los estudios desarrollados con tecnologías alternativas de nixtamalización para disminuir los efectos negativos en la calidad funcional del producto final. El uso de maíces pigmentados se ha incrementado debido al contenido superior de compuestos fenólicos, sobre todo por su contenido de antocianinas. Las antocianinas son los compuestos responsables del color rojo-azul de plantas como el maíz, y poseen propiedades antioxidantes benéficas para la salud. Estos pigmentos se encuentran en la capa de aleurona del endospermo y en el pericarpio del grano. Las antocianinas no aciladas de mayor abundancia en los maíces pigmentados son cianidina 3-glucósido (70 %), pelargonidina 3-glucósido y peonidina 3-glucósido, las cuales poseen una alta capacidad antioxidante. En general, los maíces de variedades de color morado, azul y negro son las que contienen más antocianinas. La nixtamalización tradicional es un proceso agresivo para las antocianinas contenidas en los granos pigmentados, ya que provoca pérdidas hasta de 100 % en los productos obtenidos por esta tecnología. No obstante, se puede retener una mayor cantidad de compuestos fenólicos, antocianinas y mayor capacidad antioxidante en productos obtenidos con nixtamalización por extrusión y nixtamalización fraccionada, los cuales son procesos alternativos eficientes a la nixtamalización tradicional. Sin embargo, son necesarias más investigaciones que permitan disminuir la pérdida de estos compuestos naturales útiles para la obtención de nuevos productos nutracéuticos desarrollados con maíces pigmentados.