Technological and prebiotic aspects of young bamboo culm flour (Dendrocalamus latiflorus) combined with rice flour to produce healthy extruded products.

Young bamboo culm flour (YBCF) has proved to be a healthy and sustainable ingredient, due to its high fiber content and high yield of bamboo crops. The present study evaluated the effects of YBCF from Dendrocalamus latiflorus on the physicochemical, technological properties and prebiotic activity of rice-based extrudates aiming to expand its application. The extrudates were produced in a twin-screw extruder with different RF:YBCF concentrations (100:0; 95:5, 90:10, and 85:15 %). During the process, the specific mechanical energy increased as YBCF content increased because of the high shear favored by YBCF particles. With increasing RF replacement by YBCF, the extruded products presented a significant (p < 0.05, by the Scott-Knott test) increase in hardness (57.37 to 82.01 N) and water solubility index (12.80 to 34.10 %), as well as a decrease in color luminosity (L*=85.49 to 82.83), expansion index (2.68 to 1.99), and pasting properties. In addition, all extrudate samples presented bifidogenic activity. Therefore, YBCF exhibited attractive technological properties and can be used as an ingredient in the production of healthy and sustainable extruded products.

Kinetic/thermodynamic study of immobilized ß-fructofuranosidase from Aspergillus tamarii URM4634 in chitosan beads and application on invert sugar production in packed bed reactor.

ß-fructofuranosidase (FFase) from Aspergillus tamarii URM4634 was immobilized covalently in chitosan beads. It was characterized biochemically, studied in terms of kinetic and thermodynamic parameters, and applied on conversion of sucrose for invert sugar production in a packed bed reactor (PBR). The optimum reactional conditions were determined and obtained at pH 5.0 and 60 °C. FFase was thermostable at 50-55°C. At 50°C, the enzyme shows longer half-life (t1/2) (594.13 min) and a higher D-value (1,973.64 min). This indicates that immobilized FFase was stable at temperature commonly used in invert sugar production. The following thermodynamic parameters were obtained: activation energy (E*d = 301.57 kJ mol-1), enthalpy (298.76 ≤ ΔH*d ≤ 298.89 kJ mol-1), entropy (579.88 ≤ ΔS*d ≤ 589.27 J K-1 mol-1) and Gibbs free energy (100.29 ≤ ΔG*d ≤ 108.47 kJ mol-1). The high E*d, ΔH*d and ΔG*d values confirmed FFase thermostability. The high and positive values for ΔS*d indicate an increase in disorder due opening of the enzyme structure. The sucrose hydrolysis in PBR showed a maximum invert sugar yield (96.0%) at 15 min of operation. The hydrolysis process remained efficient up to 100 min (70.22%). The results obtained in the present study provide a good indication that immobilized FFase on chitosan beads in PBR is efficient to invert sugar production for food industry.

Fructo-oligosaccharides production by an Aspergillus aculeatus commercial enzyme preparation with fructosyltransferase activity covalently immobilized on Fe3O4-chitosan-magnetic nanoparticles.

Pectinex Ultra SP-L, a commercial enzyme preparation with fructosyltransferase activity, was successfully immobilized by covalent binding to Fe3O4-chitosan- magnetic nanoparticles. Immobilization carried out according to a 23-full factorial design where glutaraldehyde concentration, activation time and time of contact between enzyme and support were selected as the independent variables and immobilization yield as the response. The highest immobilization yield (94.84%) was obtained using 3.0% (v/v) glutaraldehyde and activation and contact times of 180 and 30 min, respectively. The immobilized biocatalyst, which showed for both hydrolytic and transfructosylating activities optimum pH and temperature of 7.0 and 60 °C, respectively, retained 70 and 86% of them after 6 cycles of reuse. A kinetic/thermodynamic study focused on thermal inactivation of the immobilized construct indicated high thermostability at temperatures commonly used for fructo-oligosaccharides (FOS) production. Maximum FOS concentration obtained in lab-scale experiments was 101.56 g L-1, with predominant presence of 1-kestose in the reaction mixture. The results obtained in this study suggest that the immobilized-enzyme preparation may be effectively exploited for FOS production and easily recovered from the reaction mixture by action of a magnetic field.

Biochemical characterization and kinetic/thermodynamic study of Aspergillus tamarii URM4634 ß-fructofuranosidase with transfructosylating activity.

This study reports on the biochemical characterization as well as the kinetic and thermodynamic study of Aspergillus tamarii URM4634 ß-fructofuranosidase (FFase) with transfructosylating activity. Conditions for FFase activity were optimized by means of a central composite rotational design using pH and temperature as the independent variables, while residual activity tests carried out in the temperature range of 45-65°C enabled us to investigate FFase thermostability and estimate the kinetic and thermodynamic parameters of enzyme denaturation. Optimal conditions for sucrose hydrolysis and fructosyl transfer catalyzed by crude FFase were 50°C, and pH 6.0 and 7.4, respectively. The thermodynamic properties of irreversible enzyme inactivation were found to be activation energy of 293.1 kJ mol-1 , and activation enthalpy, entropy, and Gibbs free energy in the ranges 290.3-290.4 kJ mol-1 , 568.7-571.0 J mol-1 K-1 , and 97.9-108.8 kJ mol-1 , respectively. The results obtained in this study point out satisfactory enzyme activity and thermostability at temperatures commonly used for industrial fructo-oligosaccharide (FOS) synthesis; therefore, this novel FFase appears to be a promising biocatalyst with great potential for long-term FOS synthesis and invert sugar production. To the best of our knowledge, this is the first report on kinetic and thermodynamic parameters of an A. tamarii FFase.