Preparation of microcrystalline cellulose from residual Rose stems (Rosa spp.) by successive delignification with alkaline hydrogen peroxide.

Agricultural residues of Rose flowers (Rosa x hybrida L.) are abundant, cheap, and renewable. These lignocellulosic remains are composed of cellulose, hemicellulose, and lignin. They are an attractive feedstock to produce various value-added products, as microcrystalline cellulose (MCC). The objective of this study was to obtain MCC from residual Rose stems (RS) using a successive alkaline peroxide treatment. X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to determine the degree of crystallinity, structure characteristics, thermal properties, and morphology, respectively, of MCC. The properties of RS-MCC were compared with those of commercial MCC. The degree of crystallinity of RS-MCC was 70.21%. The X-ray diffraction patterns reveal the presence of Type I cellulose. FTIR showed the absence of non-cellulosic components, mainly lignin, present in the amorphous regions of the RS fibers. Results are promising for taking advantage of agricultural residues as a source of MCC, which could be used as a reinforcing agent in polymeric matrices.

Copper removal from wastewater by a chitosan-based biodegradable composite.

This work demonstrates that a biodegradable chitosan-based biocomposite packed in mini-reactors successfully removes copper ions from aqueous solutions. The chitosan is obtained by deacetylation of biological chitin, which is extracted from shrimp wastes by lactic acid fermentation. The polysaccharide is embedded in a biodegradable prepolymer matrix before extrusion to produce porous cylindrical pellets of 2 × 80 mm. The highest copper ion removal is 62.5 mg Cu2+ per g of the biodegradable adsorbent. Additionally, the adsorption capacity of the material, below its saturation, allows several cycles of reuse with a hydraulic retention time reduction of 1 h. This chitosan-based material is advantageous when compared with other approaches using non-biodegradable materials or costly commercial adsorbents for removing heavy metal ions in wastewater effluents as well as a filter component in water purification devices.

Thermal, conformational and rheological properties of κ-carrageenan-sodium stearoyl lactylate gels and solutions.

Polysaccharide-surfactant blends are widely used in foods. However, their possible mutual interactions have not been extensively studied. The purpose of this work was to examine how the anionic surfactant sodium stearoyl lactylate (SSL) affects different properties of κ-carrageenan solutions and gels. Rheometry, differential scanning calorimetry, asymmetrical flow field-flow fractionation coupled with multiangle laser light scattering, among others, were used to determine the flow and viscoelastic behavior, thermal transitions, and conformation changes, respectively. Interference caused by SSL is postulated as the primary factor to explain the variations in the conformation of κ-carrageenan in gels and solutions. However, electrostatic repulsions between κ-carrageenan and SSL can also be involved. These latter interactions are more important for high SSL concentrations (13 mmol dm-3) without addition of KCl, because of the higher net negative charge density of the system. SSL significantly modifies the properties of κ-carrageenan in aqueous media.

Polyelectrolyte complex of Aloe vera, chitosan, and alginate produced fibroblast and lymphocyte viabilities and migration.

Chitosan, sodium alginate and gel of Aloe vera (Aloe barbadensis Miller) were employed for the preparation of polyelectrolyte complexes at pH 4 and 6. FT-IR spectroscopy analysis showed evidence on complexes formation and incorporation of the Aloe vera gel. The ζ potential determination of the polyelectrolyte complexes revealed the presence of surface charges in the range of -20 to -24 mV, which results in stable systems. The dynamic moduli exhibited a high dependence on angular frequency, which is commonly found in solutions of macromolecules. The materials showed human fibroblast and lymphocyte viabilities up to 90% in agreement with null cytotoxicity. The polyelectrolyte complexes at pH 6 with Ca2+ were stable, showed high water absorption, satisfactory morphology, pore size and rigidity, characteristics that allowed significant human fibroblast migration in wound closure in vitro assays.

Modeling the pressure inactivation of Escherichia coli and Salmonella typhimurium in sapote mamey ( Pouteria sapota (Jacq.) H.E. Moore & Stearn) pulp.

High hydrostatic pressure inactivation kinetics of Escherichia coli ATCC 25922 and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028 ( S. typhimurium) in a low acid mamey pulp at four pressure levels (300, 350, 400, and 450 MPa), different exposure times (0-8 min), and temperature of 25 ± 2℃ were obtained. Survival curves showed deviations from linearity in the form of a tail (upward concavity). The primary models tested were the Weibull model, the modified Gompertz equation, and the biphasic model. The Weibull model gave the best goodness of fit ( R2adj > 0.956, root mean square error < 0.290) in the modeling and the lowest Akaike information criterion value. Exponential-logistic and exponential decay models, and Bigelow-type and an empirical models for b'( P) and n( P) parameters, respectively, were tested as alternative secondary models. The process validation considered the two- and one-step nonlinear regressions for making predictions of the survival fraction; both regression types provided an adequate goodness of fit and the one-step nonlinear regression clearly reduced fitting errors. The best candidate model according to the Akaike theory information, with better accuracy and more reliable predictions was the Weibull model integrated by the exponential-logistic and exponential decay secondary models as a function of time and pressure (two-step procedure) or incorporated as one equation (one-step procedure). Both mathematical expressions were used to determine the td parameter, where the desired reductions ( 5D) (considering d = 5 ( t5) as the criterion of 5 Log10 reduction (5 D)) in both microorganisms are attainable at 400 MPa for 5.487 ± 0.488 or 5.950 ± 0.329 min, respectively, for the one- or two-step nonlinear procedure.

Inhibition of Listeria monocytogenes in Fresh Cheese Using Chitosan-Grafted Lactic Acid Packaging.

A chitosan from biologically obtained chitin was successfully grafted with d,l-lactic acid (LA) in aqueous media using p-toluenesulfonic acid as catalyst to obtain a non-toxic, biodegradable packaging material that was characterized using scanning electron microscopy, water vapor permeability, and relative humidity (RH) losses. Additionally, the grafting in chitosan with LA produced films with improved mechanical properties. This material successfully extended the shelf life of fresh cheese and inhibited the growth of Listeria monocytogenes during 14 days at 4 °C and 22% RH, whereby inoculated samples with chitosan-g-LA packaging presented full bacterial inhibition. The results were compared to control samples and commercial low-density polyethylene packaging.

Chia (Salvia hispanica): A Review of Native Mexican Seed and its Nutritional and Functional Properties.

In this chapter, a review is made on various aspects of chia seed in order to provide an overall, yet comprehensive view, about this important commodity with the aim of updating the current state of knowledge on its composition, possible nutraceutical properties, and potential benefits for human health. Based on this approach, the discussion includes some comments on the main historical aspects, morphology of the seed, its importance in the diet of humans and stresses the main results issued from investigations on its three main components; lipid, protein, and fiber. The chapter closes with a discussion on the potential benefits for human health, highlighting the contradictions that still exist in this area and the need for continued research in this direction and considerations on the role of chia seed as a functional food.

Lipase-catalyzed synthesis of hyperbranched poly-L-lactide in an ionic liquid.

Hyperbranched poly-L-lactides have been synthesized by eROP in [C4MIM][PF6] media. The bis(hydroxymethyl)butyric acid molecule was used as the AB2 core co-monomer and immobilized lipase B from Candida antarctica as biocatalyst. The degree of branching could be controlled by the reaction conditions, with the maximum achieved being 0.21. The successful achievement of the hyperbranched structure is attributed to the high solvent power of substrates and products in the ionic liquid besides sustained lipase activity.

Enzymatic synthesis of poly-L-lactide and poly-L-lactide-co-glycolide in an ionic liquid.

The syntheses of poly-L-lactide (PLLA) and poly-L-lactide-co-glycolide (PLLGA) is reported in the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF(6)] mediated by the enzyme lipase B from Candida antarctica (Novozyme 435). The highest PLLA yield (63%) was attained at 90 degrees C with a molecular weight (M(n)) of 37.8 x 10(3) g/mol determined by size exclusion chromatography. This procedure produced relatively high crystalline polymers (up to 85% PLLA) as determined by DSC. In experiments at 90 degrees C product synthesis also occurred without biocatalyst, however, PLLA synthesis in [HMIM][PF(6)] at 65 degrees C followed only the enzymatic mechanism as ring opening was not observed without the enzyme. In addition, the enzymatic synthesis of PLLGA is first reported here using Novozyme 435 biocatalyst with up to 19% of lactyl units in the resulting copolymer as determined by NMR. Materials were also characterized by TGA, MALDI-TOF-MS, X-ray diffraction, polarimetry and rheology.