Enzymatic Cross-Linking of Alkali Extracted Arabinoxylans: Gel Rheological and Structural Characteristics

Ferulated arabinoxylans were alkali-extracted from wheat bran at different incubation times (0.0, 0.5, 1.0, 1.5 and 2.0 h). Wheat bran ferulated arabinoxylans (WBAX) arabinose-to-xylose ratio, ferulic acid content, intrinsic viscosity and viscosimetric molecular weight values decreased as the incubation time of extraction increased. WBAX enzymatic cross-linking capability was affected by incubation time while an increase in WBAX concentration from 5 to 6% (w/v) favored gelation. The WBAX gels formed presented a macroporous structure with mesh size ranging from 40 to 119 nm and hardness values varying from 1.7 to 5 N

Raleo químico de flores de manzano (Malus x domestica Borkh.) 'Golden Delicious' y 'RedChief Delicious'

Aunque el raleo es una práctica común en la región productora de manzana (Malus x domestica Borkh.) del estado de Chihuahua, aún es frecuente que se lleve a cabo de manera manual, tardía, poco eficiente y costosa. El raleo químico es una práctica cada vez más común. En manzano, el raleo de flores o frutos incrementa la calidad de los frutos y reduce la alternancia en la producción. Para maximizar los beneficios de esta práctica, se evaluó la eficiencia de los siguientes compuestos asperjados durante la floración: ácido naftalenacético, cianamida hidrogenada, tiosulfato de amonio, bencil adenina, ácido giberélico y una mezcla de cal-azufre y aceite de pescado como raleadores químicos de flores en los cultivares Golden Delicious y RedChief Delicious. Otro tratamiento consistió en las aplicaciones de la mezcla de cal-azufre y aceite de pescado en floración, además de una aspersión con ácido naftalenacético en post-floración. Los resultados se compararon con un testigo con un raleo manual tardío y un tratamiento con raleo manual en floración. En ambos cultivares, el tratamiento de cal-azufre en floración y ácido naftalenacético en post-floración, redujo significativamente el cuajado de frutos sin reducir el rendimiento a cosecha. Además, con este mismo tratamiento se obtuvieron los frutos de mayor tamaño a la cosecha. Los tratamientos con cal-azufre y aceite de pescado provocaron roseteado en los frutos ‘Golden Delicious’. El tratamiento con ácido naftalenacético en floración redujo significativamente la alternancia de la producción observada en ‘Golden Delicious’. Abstract Although thinning is a common practice in the productive apple (Malus x domestica Borkh.) region in the state of Chihuahua, it is still often performed manually, belated, innefficient and costly. Chemical thinning is an increasingly common practice. In apple trees, flower or fruit thinning increases the fruit quality and reduces alternate bearing in the apple production. To maximize the benefits of this practice, it was assessed efficiency of the following products: naphthaleneacetic acid, hydrogen cyanamide, ammonium thiosulfate, benzyladenine, gibberelic acid, and a mixture of lime-sulfur and fish oil as chemical thinners of flowers in the cultivars Golden Delicious and RedChief Delicious, sprayed during bloom was evaluated. Another treatment consisted of the application of the lime-sulfur mixture and fish oil at bloom plus a spraying with naphthaleneacetic acid at post-bloom stage. The results were compared with a late manual thinning as control, and with a treatment of manual thinning during bloom. In both cultivars, the treatment with lime- sulfur at bloom and naphthaleneacetic acid at post-bloom, significantly reduced fruit set without reducing crop yield. Furthermore, there were obtained larger fruits at harvest with this same treatment. Treatments with lime-sulfur and fish oil resulted in russeting on 'Golden Delicious' fruits. Naphthaleneacetic acid treatment during bloom significantly reduced alternate bearing observed in cv. 'Golden Delicious'. Keywords: Malus x domestica Borkh., fruit set, return bloom, russeting

Maize Arabinoxylan Gels as Protein Delivery Matrices

The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v) in the presence of insulin or β-lactoglobulin at 0.1% (w/v) was investigated. Insulin and β-lacto-globulin did not modify either the gel elasticity (9 Pa) or the cross-links content (0.03 and 0.015 mg di- and triferulic acids/mg arabinoxylan, respectively). The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 × 10-7 and 0.79 × 10-7 cm2/s for insulin (5 kDa) and β-lactoglobulin (18 kDa), respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins

Protein/Arabinoxylans Gels: Effect of Mass Ratio on the Rheological, Microstructural and Diffusional Characteristics

Wheat bran arabinoxylan (WBAX) gels entrapping standard model proteins at different mass ratios were formed. The entrapment of protein affected the gel elasticity and viscosity values, which decreased from 177 to 138 Pa. The presence of protein did not modify the covalent cross-links content of the gel. The distribution of protein through the network was investigated by confocal laser scanning microscopy. In mixed gels, protein aggregates forming clusters were detected at protein/polysaccharide ratios higher than 0.25. These clusters were not homogeneously distributed, suggesting that WBAX and protein are located in two different phases. The apparent diffusion coefficient (Dm) of proteins during release from mixed gels was investigated for mass ratios of 0.06 and 0.12. For insulin, Dm increased significantly from 2.64 × 10−7 to 3.20 × 10−7 cm2/s as the mass ratio augmented from 0.06 to 0.12. No significant difference was found for Dm values of ovalbumin and bovine serum albumin released from the mixed gels. The results indicate that homogeneous protein/WBAX gels can be formed at low mass ratios, allowing the estimation of Dm by using an analytical solution of the second Fick’s law