Renata Cristina Ferreira Bonomo

Application of the response surface methodology for optimization of whey protein partitioning in PEG/phosphate aqueous two-phase system.

In order to develop a new strategy for β-lactoglobulin (β-lg) removal from whey protein, partitioning of α-lactalbumin (α-la), β-lg and glycomacropeptide (Gmp) was studied using aqueous two phase systems (ATPS). A system composed of 13% (w/w) polyethylene glycol (PEG, average molar mass 2000 g/mol) and 13% (w/w) potassium phosphate was used at 25°C. A central composite rotatable design (CCRD) associated to the response surface methodology (RSM) was applied to investigate the effects of NaCl concentration and pH on the partition of these proteins. It was found that α-la and Gmp partitioned to the top phase rich in PEG, whereas β-lg partitioned to the bottom phase rich in salt. According to the RSM, optimal conditions for β-lg removal where found where pH was equal to 6.7 and salt concentration was 0.35 mol/L. Under these conditions, the partition coefficient K(α) was 0.48 and K(Gmp) was 0.92. On the other hand, the partition coefficient K(β) was only 0.01. In such conditions β-lg preferentially concentrates in the bottom phase, while the top phase exclusively contains the proteins α-la and Gmp. Fractionation of the proteins from fresh whey was performed in a three stage cross-flow extraction system. The extraction yield for β-lg in the bottom phase was 97.3%, while the yields for α-la and Gmp in the top phase were 81.1% and 97.8%, respectively.

Microcalorimetric study of adsorption of glycomacropeptide on anion-exchange chromatography adsorbent

The adsorption of glycomacropeptide (GMP) from cheese whey on an anion-exchange adsorbent was investigated using isothermal titration microcalorimetry to measure thermodynamic information regarding such processes. Isotherms data were measured at temperatures of 25 and 45 degrees C, pH 8.2 and various ionic strengths (0-0.08 molL(-1) NaCl). The equilibrium data were fit using the Langmuir model and the process was observed to be reversible. Temperature was observed to positively affect the interaction of the protein and adsorbent. Microcalorimetric studies indicated endothermic adsorption enthalpy in all cases, except at 45 degrees C and 0.0 molL(-1) NaCl. The adsorption process was observed to be entropically driven at all conditions studied. It was concluded that the increase in entropy, attributed to the release of hydration waters as well as bounded ions from the adsorbent and protein surface due to interactions of the protein and adsorbent, was a major driving force for the adsorption of GMP on the anion-exchange adsorbent. These results could allow for design of more effective ion-exchange separation processes for proteins.

Statistical Optimization of Culture Conditions and Characterization for Ligninolytic Enzymes Produced from Rhizopus Sp. Using Prickly Palm Cactus Husk

Dry prickly palm cactus (Nopalea cochenillifera) husk was investigated as a substrate for Rhizopus sp. cultivation in the solid state, aiming at the production of laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP). The optimization of fermentation was evaluated by an experimental design and it was obtained, for each enzyme, maximum productivities (U g−1 h−1) of: 0.085 ± 0.02 (MnP), 0.066 ± 0.001 (LiP), and 0.023 ± 2.3.10−4 (Lac), at the conditions of 10 g of substrate, 72 h of fermentation, aw = 0.865, and 30°C. The enzymes thermal and pH stabilities were evaluated and it was observed better results at temperatures no higher than 60°C and pH of 5.0; in addition, the storage of these enzymes was better at − 25°C than at 4°C. Since the prickly palm cactus is an agricultural substrate and specially because of its low cost, it is important to propose different applications for it as, for example, an alternative substrate for biotechnological processes.

Thermophysical properties of umbu pulp

Summary The effects of moisture content (between 65 and 95%) and temperature (between 5 and 85 °C) on the specific mass, specific heat, thermal diffusivity and thermal conductivity of umbu pulp were studied. The specific mass decreased when the moisture content and temperature increased, and the thermal diffusivity and thermal conductivity increased as the moisture content decreased and the temperature increased as from 25 °C. There was also an increase in specific heat as the moisture content increased. Models adequately describing the observed experimental behaviour were adjusted by regression analysis, and the results will be useful for the further development and adaptation of the equipment necessary for umbu pulp processing.

Comparison between the univariate and multivariate analysis on the partial characterization of the endoglucanase produced in the solid state fermentation by Aspergillus oryzae ATCC 10124

ABSTRACT Endoglucanase production by Aspergillus oryzae ATCC 10124 cultivated in rice husks or peanut shells was optimized by experimental design as a function of humidity, time, and temperature. The optimum temperature for the endoglucanase activity was estimated by a univariate analysis (one factor at the time) as 50°C (rice husks) and 60°C (peanut shells), however, by a multivariate analysis (synergism of factors), it was determined a different temperature (56°C) for endoglucanase from peanut shells. For the optimum pH, values determined by univariate and multivariate analysis were 5 and 5.2 (rice husk) and 5 and 7.6 (peanut shells). In addition, the best half-lives were observed at 50°C as 22.8 hr (rice husks) and 7.3 hr (peanut shells), also, 80% of residual activities was obtained between 30 and 50°C for both substrates, and the pH stability was improved at 5–7 (rice hulls) and 6–9 (peanut shells). Both endoglucanases obtained presented different characteristics as a result of the versatility of fungi in different substrates.

Thermophysical Characterization of Genipap Pulp

The influence of temperature and water content on thermophysical properties (density, thermal diffusivity, thermal conductivity and specific heat) of genipap (Genipa americana, L) pulp at medium maturity were studied. The thermophysical properties were determined at concentrations between 6.0% m/m and 24.0% m/m of water content and temperatures range of 5 to 80°C. The density decreased with increase in temperature and water content, while the thermal diffusivity and conductivity increased as temperature and water content increased. The specific heat decreased with the moisture content. Empirical models were fitted to the experimental data for each property and the accuracy of those models was checked.

Biodegradable thermoplastic starch of peach palm (Bactris gasipaes kunth) fruit: Production and characterisation

ABSTRACT The objective of this study was to produce and characterise biodegradable thermoplastic starch (TPS) derived from the fruit of pejibaye palm (Bactris gasipaes Kunth) plasticised with glycerol and sorbitol. The plasticised starch yielded a strength (σ) of 1.3 ± 0.2 MPa, deformation (ε) of 9.4 ± 1.6%, and Young’s modulus (E) of 191 ± 72.0 MPa. The thermal analysis showed a 61.14% mass loss over the temperature range 290–388°C and an endothermic peak at 130°C. X-ray diffractograms of the TPS revealed peaks corresponding to crystallites of type Vh at 19.4° and type V at 22.6°. Morphological studies, by scanning electron microscopy, showed the plasticised starch had a homogeneous surface, without phase separation and without cracks, with few granules not gelatinised. The analysis of its biodegradation by soil burial tests showed a total mass loss of 84.4 ± 4.4%, after 18 weeks. Biodegradable TPS was successfully obtained from the pejibaye palm fruit, presenting resistant to traction and to the thermal degradation.

Thermal-morphological characterisation of starch from peach-palm (Bactris Gasipaes kunth) fruit (Pejibaye)

ABSTRACT The objective of this study was to characterize the starch of the peach-palm fruit. The starch was subjected to thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy. The thermogravimetric analysis showed 76.62% of the weight loss in the temperature range from 251.7 to 380.6 ºC. The peak in differential scanning calorimetry was obtained at 70.0 ºC. Fourier transform infrared spectroscopy were obtained with a wavelength band of 528 to 3421 cm−1. The x-ray diffraction corresponded to C-type crystals. The granule sizes ranged from 1.60 to 8.48 μm.