Functional properties of guava seed glutelins

Five guava seed glutelin extracts were obtained with different buffer solutions: Na2B4O7 alone (Glut.Bo) or containing SDS (Glut.BoSDS), 2-mercaptoethanol (Glut.Bo2-ME), or a combination of both (Glut.BoSDS2-ME) and NaOH (Glut.Na). All borate buffer solutions were at pH 10. The higher yield of glutelins corresponded to the Glut.BoSDS extract (81.9% dry basis) and the lower to Glut.Bo (6.8%). The functional properties of the five guava seed glutelin extracts were determined. Glut.BoSDS, Glut.BoSDS2-ME, and Glut.Na showed high values for several properties, including surface hydrophobicity (7.7, 10.8, and 0.6, respectively), solubility at pH 10 (91.1, 77.9, and 96.7, respectively), water-holding capacity at pH 3.6 (1.7, 2.5, and 2.8, respectively), emulsifying activity index (pH 10; 503.5, 238.2, and 838.0, respectively), and foaming properties (pH 10; V0 = 0.14, 0.25, and 0.19, respectively; Vmax = 6.1, 5.59, and 4.51, respectively; t1/2 = 266, 255.3, and 94 s, respectively). These results suggest that the denaturing reagent (SDS or NaOH) during extraction conferred on the proteins a structure that facilitated the development of their functional properties.Fil: Bernardino Nicanor, Aurea. INSTITUTO POLITÉCNICO NACIONAL (IPN);Fil: Añon, Maria Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Scilingo, Adriana Alicia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Dávila Ortíz, Gloria. INSTITUTO POLITÉCNICO NACIONAL (IPN)

Influence of starch source in the required hydrolysis time for the production of maltodextrins with different dextrose equivalent

The starches were statistically different (p < 0.05) in their protein, ash, fat, phosphorus, amylose and amylopectin content. The amylose/amylopectin ratios in corn, potato and rice starches were 0.389, 0.282 and 0.220, respectively. The phosphorus content in the same order of starches was: 0.15 ± 0.01; 0.80 ± 0.02 and 0.95 ± 0.02 g/kg, respectively. The chemical composition of the different starches, and specifically its amylose and amylopectin content, its phosphorus content and the way it is bound to the starch molecule, affect the functional properties like the viscosity of gels and the enzymatic hydrolysis rate of these molecules. The rice starch is easily hydrolyzed by the á-amylase enzyme from Aspergillus oryzae and therefore, it required less time to obtain maltodextrin by enzymatic hydrolysis from rice starch compared with those from corn or potato starch. Under saturation conditions of the enzyme, the dextrose equivalent content was proportional to the hydrolysis time, regardless of the starting starch source.Key words: Starch, maltodextrins, dextrose equivalent, amylose, amylopectin

Effect of the fructose and glucose concentration on the rheological behavior of high fructose syrups

The objective of this work was to study the effect of fructose and glucose content on the rheological behavior of syrups. Initially, high fructose syrup from the fructans present in leaves, bases and head of Agave tequilana Weber blue was obtained. Then, its contents of moisture, ash, fructose, glucose and direct and total reducing sugars were determined. Finally, the physicochemical properties of the syrups were evaluated and compared with a high commercial fructose corn syrup (Frudex 55) and other fructose, glucose and sucrose syrups. All of them had the same temperature and concentration of total solids. All syrups behaved as Newtonian fluids and had no statistically significant differences (p <0.05) in their density, water activity and in direct and total reducing sugars. The viscosity and surface tension of syrup depended on its fructose and glucose content. Also, greater fructose content produces syrups with lower viscosity and lower surface tension.Keywords: High fructose syrups, viscosity, rheological behavior, Newtonian fluidsAfrican Journal of Biotechnology, Vol. 12(12), pp. 1401-140

MECANISMOS DE SILENCIAMIENTO GÉNICO DURANTE EL DESARROLLO DEL GAMETOFITO FEMENINO EN Arabidopsis thaliana (MECHANISMS OF GENE SILENCING DURING THE DEVELOPMENT OF THE FEMALE GAMETOPHYTE IN Arabidopsis thaliana)

ResumenSilenciar un gen significa disminuir la expresión del mismo y a partir de los efectos, afectar su función, actuando a diferentes niveles, por ejemplo, silenciamiento transcripcional (TGS), silenciamiento post-transcripcional (PTGS) y traduccional. Los cuales, presentan elementos comunes mediados por ARNs pequeños (RNAp), que proporcionan especificidad y se acomplejan con proteínas efectoras del silenciamiento génico. Recientemente se reportó la participación de ARNs pequeños  en la determinación de la identidad de la célula madre de la megaspora. En este trabajo se plantea una estrategia para estudiar las rutas de silenciamiento que participan en la regulación de la identidad celular durante el desarrollo del gametofito femenino. Para lo anterior se generaron líneas silenciadoras del gen GUS (GUSRNAi). Posteriormente se seleccionaron algunas de estas líneas para ser cruzadas con los marcadores del desarrollo del gemetofito femenino. Se obtuvieron imágenes que reflejaron la actividad de las líneas marcadoras durante el desarrollo reproductivo. En las plantas de la línea GUSRNAi;Marcadora se observó una expresión atenuada o nula del marcador de identidad. Lo anterior demostró la capacidad de la lineas para llevar a cabo silenciamiento génico en células del gametofino femenino.Palabras clave: Gametogénesis, linaje celular, ARNs. AbstracSilencing a gene means decreasing its expression affecting its function, acting at different levels, for example transcriptional silencing (TGS), post-transcriptional silencing (PTGS) and translational silencing. They present common elements mediated by small RNAs (RNAs), which provide specificity and form complexes with gene silencing effector proteins. The participation of small RNAs in the determination of the identity of the megaspore mother cell was recently reported. In this work, a strategy is proposed to study the gene silencing pathways involved in the regulation of cell identity during the development of the female gametophyte. For this, we generated silencing lines of the GUS gene (GUSRNAi). Subsequently, some of these lines were selected to be crossed with the developmental marker of the female gametophyte, ET2209. Images that reflected the activity of the marker lines during reproductive development were obtained. While in plants GUSRNAi;ET2209 we observed an attenuated or null expression of the identity cell marker. The above demonstrated the ability of these lines to carry out gene silencing in female gametophyte cells.Keywords: Gametogenesis, cell lineage, RNAs

Agave Seeds: Physical and Chemical Characterization and Identification of Storage Proteins

ABSTRAC

Effect of Dual Modification on the Spectroscopic, Calorimetric, Viscosimetric and Morphological Characteristics of Corn Starch

The effect of dual modification of corn starch, including hydrolysis and succinylation, were evaluated through peak viscosity (PV) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. This dual modification was shown to increase the reaction efficiency (RE) and degree substitution (DS) compared with starches that were not subjected to acid hydrolysis pretreatment with a 44% and 45% increase respectively. After acid hydrolysis pretreatment, the surface of the corn starch granules exhibited exo-erosion and whitish points due to the accumulation of succinyl groups. The peak viscosity was reduced significantly with the acid hydrolysis pretreatment (between 3 and 3.5-fold decrease), which decreased the pasting temperature and peak time to 20 °C and 100 s respectively. In addition, the dual modification of corn starch altered certain thermal properties, including a reduction in the enthalpy of gelatinization (ΔH) and a higher range of gelatinization (around 6 °C), which may effectively improve industrial applications. Modifications on the FTIR spectra indicated that the dual modification affected the starch crystallinity, while the Raman spectra revealed that the dual modification disrupted the short-range molecular order in the starch. Rearrangement and molecular destabilization of the starch components promoted their granular amphiphilic properties

Partial Purification and Characterization of the Lectins of Two Varieties of <i>Phaseolus coccineus</i> (Ayocote Bean)

In this study, a partial purification and characterization of the lectins from two varieties of Phaseolus coccineus (black and purple ayocote bean) was carried out. A partial purification of the lectins was performed by affinity chromatography on fetuin-agarose. The lectins’ characterization showed that the hemagglutination activity was only inhibited by the fetuin and that the saccharides (mono-, di- and tri-saccharides) do not influence their hemagglutination capacity. A difference in the relative molecular weight between the two Phaseolus varieties was observed, 28.5 kDa for the black variety and 30.6 kDa for the purple variety. In the lectins of both Phaseolus varieties, ions were detected in their structure and influenced their hemagglutination activity, principally to the ion Ca+2; on the other hand, only the lectins of the purple variety of the Phaseolus, had a detectable ion, Cu+2. The lectins showed thermostability in the temperature range of 25 and 70 °C, on the other hand, in the pH range between 3 and 10, the lectins showed hemagglutination activity. According to the obtained results, the structural differences between the lectins obtained from both Phaseolus varieties influence their hemagglutination activity

Physical–chemical characterization and antioxidant properties of extruded products made from mixtures composed of corn grits and red potato flour (Oxalis tuberosa)

Some physicochemical characteristics and antioxidant activity of extrudates made from corn grits and red potato flour were evaluated. The inclusion of red potato flour altered values of water absorption index, water solubility index, expansion index and fracturability of extrudates. Color analysis of extrudates showed a reduction of luminosity from 44.37 ± 0.87 to 25.06 ± 1.74. Likewise, extrudates made with red potato flour at 100% presented higher content of total phenols compared to the control extrudates (0.44 ± 0.02 and 2.88 ± 0.03 mg GA/g dry sample, respectively); consequently, an increase in antioxidant capacity was observed using DPPH, ABTS and FRAP assays. The images obtained by fluorescence microscopy provided information on the protein content. The proximal chemical analysis indicated that extrudates substituted with red potato flour at 10% showed higher protein content (7.78 g/100 g), compared to T5. This study concludes that when adding red potato flour, is possible to develop extrudates with good physicochemical characteristics and antioxidant properties