Hydrolysis of xylans by enzyme systems from solid cultures of Trichoderma harzianum strains

Xylanase activity was isolated from crude extracts of Trichoderma harzianum strains C and 4 grown at 28oC in a solid medium containing wheat bran as the carbon source. Enzyme activity was demonstrable in the permeate after ultrafiltration of the crude extracts using an Amicon system. The hydrolysis patterns of different xylans and paper pulps by xylanase activity ranged from xylose, xylobiose and xylotriose to higher xylooligosaccharides. A purified ß-xylosidase from the Trichoderma harzianum strain released xylose, xylobiose and xylotriose from seaweed, deacetylated, oat spelt and birchwood xylans. The purified enzyme was not active against acetylated xylan and catalyzed the hydrolysis of xylooligosaccharides, including xylotriose, xylotetraose and xylopentaose. However, the enzyme was not able to degrade xylohexaose. Xylanase pretreatment was effective for hardwood kraft pulp bleaching. Hardwood kraft pulp bleached in the XEOP sequence had its kappa number reduced from 13.2 to 8.9 and a viscosity of 20.45 cp. The efficiency of delignification was 33%.

Propofol pretreatment attenuates lipopolysaccharide-induced acute lung injury in rats by activating the phosphoinositide-3-kinase/Akt pathway

The aim of this study was to investigate the effect of propofol pretreatment on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the role of the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway in this procedure. Survival was determined 48 h after LPS injection. At 1 h after LPS challenge, the lung wet- to dry-weight ratio was examined, and concentrations of protein, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in bronchoalveolar lavage fluid (BALF) were determined using the bicinchoninic acid method or ELISA. Lung injury was assayed via lung histological examination. PI3K and p-Akt expression levels in the lung tissue were determined by Western blotting. Propofol pretreatment prolonged survival, decreased the concentrations of protein, TNF-α, and IL-6 in BALF, attenuated ALI, and increased PI3K and p-Akt expression in the lung tissue of LPS-challenged rats, whereas treatment with wortmannin, a PI3K/Akt pathway specific inhibitor, blunted this effect. Our study indicates that propofol pretreatment attenuated LPS-induced ALI, partly by activation of the PI3K/Akt pathway.

LENTIL TANNIN-GLOBULIN INTERACTIONAND AND IN VITRO HYDROLYSIS

Protein fractions were isolated from lentil cotyledons and tannins were isolated and purified from lentil seed coats. The globulin fraction corresponded to 42.7% of the total lentil flour nitrogen, representing the major protein fraction. Acetone:water (7:3) was the best extractant for seed coat tannins compared to methanol or methanol-HCl 1%. Native and heated (99oC/15 min.) isolated lentil globulin and casein were hydrolyzed with trypsin and pepsin in the absence of tannins and at 1:40, 1:20, 1:10, 1:5 and 1:2.5 tannin-to-protein ratios. The tryptic and peptic hydrolysis of the unheated proteins were reduced with increasing tannin-to-protein ratios. Unheated casein showed to be more susceptible to trypsin than globulin and the opposite effect was observed with pepsin. Heating followed by tannin interaction and hydrolysis had a more pronounced effect on tryptic than peptic digestion for both proteins.

Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches

Enzymatic hydrolysis of granular starch is an important tool to provide information about granule structure. Cassava, sweet potato, Peruvian carrot, and potato starches were hydrolyzed by bacterial α-amylase at 37 °C for 48 hours, and the physicochemical properties of the residues from hydrolysis were determined. Cassava starch was the most susceptible to enzyme displaying 20.9% of hydrolysis, whereas potato starch was the most resistant with 5.9%. The granule average size varied from 10.8 to 23.4 μm for Peruvian carrot and potato starches, respectively. With the use of SEM, a smooth granule surface was observed for all native starches. Cassava and sweet potato starches displayed an A-type X-ray diffraction pattern, while Peruvian carrot and potato starches showed a B-type pattern. After hydrolysis, cassava, sweet potato, and Peruvian carrot starches showed some well degraded granules, whereas potato starch presented a slight sign of degradation. The amylose content of the starches decreased with hydrolysis for cassava, sweet potato, and Peruvian carrot starches and was kept unchanged for the potato starch. As expected, intrinsic viscosity and pasting properties decreased for all hydrolyzed starches. There is no difference between thermal properties of native and hydrolyzed starches. These results suggested that hydrolysis occurred in amorphous and crystalline areas of the granules. The B type diffraction pattern in conjunction with the big granule size of the potato starch may have contributed to the greatest resistance of this starch to hydrolysis.

The effect of acid hydrolysis on the technological functional properties of pinhão (Araucaria brasiliensis) starch

Technological functional properties of native and acid-thinned pinhão (seeds of Araucária angustifolia, Brazilian pine) starches were evaluated and compared to those of native and acid-thinned corn starches. The starches were hydrolyzed (3.2 mol.L-1 HCl, 44 ºC, 6 hours) and evaluated before and after the hydrolysis reaction in terms of formation, melting point and thermo-reversibility of gel starches, retrogradation (in a 30-day period and measurements every three days), paste freezing and thawing stability (after six freezing and thawing cycles), swelling power, and solubility. The results of light transmittance (%) of pastes of native and acid-thinned pinhão starches was higher (lower tendency to retrogradation) than that obtained for corn starches after similar storage period. Native pinhão starch (NPS) presented lower syneresis than native corn starch (NCS) when submitted to freeze-thaw cycles. The acid hydrolysis increased the syneresis of the two native varieties under storage at 5 ºC and after freezing and thawing cycles. The solubility of NPS was lower than that of native corn starch at 25, 50, and 70 ºC. However, for the acid-thinned pinhão starch (APS), this property was significantly higher (p < 0.05) when compared to that of acid-thinned corn starch (ACS). From the results obtained, it can be said that the acid treatment was efficient in producing a potential fat substitute from pinhão starch variety, but this ability must be further investigated.

Effects of sequential enzymatic hydrolysis on structural, bioactive and functional properties of Phaseolus lunatus protein isolate

Significant initiatives exist within the global food market to search for new, alternative protein sources with better technological, functional, and nutritional properties. Lima bean (Phaseolus lunatus L.) protein isolate was hydrolyzed using a sequential pepsin-pancreatin enzymatic system. Hydrolysis was performed to produce limited (LH) and extensive hydrolysate (EH), each with different degrees of hydrolysis (DH). The effects of hydrolysis were evaluated in vitro in both hydrolysates based on structural, functional and bioactive properties. Structural properties analyzed by electrophoretic profile indicated that LH showed residual structures very similar to protein isolate (PI), although composed of mixtures of polypeptides that increased hydrophobic surface and denaturation temperature. Functionality of LH was associated with amino acid composition and hydrophobic/hydrophilic balance, which increased solubility at values close to the isoelectric point. Foaming and emulsifying activity index values were also higher than those of PI. EH showed a structure composed of mixtures of polypeptides and peptides of low molecular weight, whose intrinsic hydrophobicity and amino acid profile values were associated with antioxidant capacity, as well as inhibiting angiotensin-converting enzyme. The results obtained indicated the potential of Phaseolus lunatus hydrolysates to be incorporated into foods to improve techno-functional properties and impart bioactive properties.

Evaluation of jumbo squid (Dosidicus gigas) byproduct hydrolysates obtained by acid-enzymatic hydrolysis and by autohydrolysis in practical diets for Pacific white shrimp (Litopenaeus vannamei)

The marine bioprocessing industry offers great potential to utilize byproducts for fish meal replacement in aquafeeds. Jumbo squid is an important fishery commodity in Mexico, but only the mantle is marketed. Head, fins, guts and tentacles are discarded in spite of being protein-rich byproducts. This study evaluated the use of two jumbo squid byproduct hydrolysates obtained by acid-enzymatic hydrolysis (AEH) and by autohydrolysis (AH) as ingredients in practical diets for shrimp. The hydrolysates were included at levels of 2.5 and 5.0% of the diet dry weight in four practical diets, including a control diet without hydrolysate. Shrimp growth and survival were not significantly affected by the dietary treatments. Postharvest quality of abdominal muscle was evaluated in terms of proximate composition and sensory evaluation. Significantly higher crude protein was observed in the muscle of shrimp fed the highest hydrolysate levels, AH 5% (204.8 g kg- 1) or AEH 5% (201.3 g kg- 1). Sensory analysis of cooked muscle showed significant differences for all variables evaluated: color, odor, flavor, and firmness. It was concluded that Jumbo squid byproducts can be successfully processed by autohydrolysis or acid-enzymatic hydrolysis, and that up to 5.0% of the hydrolysates can be incorporated into shrimp diets without affecting growth or survival.

Lactose hydrolysis potential and thermal stability of commercial β-galactosidase in UHT and skimmed milk

Abstract The commercial enzyme (E.C. = 3.2.1.23) from Kluyveromyces lactis (liquid) and Aspergillus oryzae(lyophilized) was investigated for its hydrolysis potential in lactose substrate, UHT milk, and skimmed milk at different concentrations (0.7; 1.0 and 1.5%), pH values (5.0; 6.0; 6.5 and 7.0), and temperature (30; 35; 40 and 55 ºC). High hydrolysis rates were observed for the enzyme from K. lactis at pH 7.0 and 40 ºC, and from A. oryzae at pH 5.0 and 55 ºC. The enzyme from K. lactis showed significantly higher hydrolysis rates when compared to A. oryzae. The effect of temperature and β-galactosidase concentration on the lactose hydrolysis in UHT milk was higher than in skimmed milk, for all temperatures tested. With respect to the thermal stability, a decrease in hydrolysis rate was observed at pH 6.0 at 35 ºC for K. lactisenzyme, and at pH 6.0 at 55 ºC for the enzyme from A. oryzae. This study investigate the hydrolysis of β-galactosidase in UHT and skimmed milk. The knowledge about the characteristics of the β-galactosidase fromK. lactis and A. oryzae enables to use it most efficiently to control the enzyme concentration, temperature, and pH in many industrial processes and product formulations.

Influence of the degree of hydrolysis and type of enzyme on antioxidant activity of okara protein hydrolysates

Abstract The objective of this work was to evaluate the antioxidant activity of protein hydrolysates obtained by the enzymatic hydrolysis of okara using an endopeptidase (Alcalase) and exopeptidase (Flavourzyme). The reaction was monitored by the pH-stat procedure in which five aliquots were collected during the hydrolysis by each enzyme, corresponding to different degrees of hydrolysis (DH). The antioxidant activities of the aliquots were evaluated by the ABTS, DPPH and FRAP methods. For the hydrolysates obtained using Alcalase, the antioxidant activities increased from: 68.6 to 99.5% (ABTS), 14.5 to 17.7% (DPPH) and 222.6 to 684.9 µM Trolox (FRAP), when the DH varied from 0 to 33.6%. With respect to Flavourzyme, the results were: 67.2 to 88.2% (ABTS), 9.5 to 18.5% (DPPH) and 168.0 to 360.3 µM Trolox (FRAP), when the DH increased up to 5.8%. The results showed that the protein hydrolysates had antioxidant capacities, which were influenced by the degree of hydrolysis and the type of enzyme.

ORGANOSILICON BIOTECHNOLOGY: A BIO-INSPIRED APPROACH TO THE HYDROLYSIS OF ALKOXYSILANES and THE LIPASE-CATALYZED SYNTHESIS OF SILOXANE-CONTAINING POLYESTERS AND POLYAMIDES

The first part of this thesis studied the capacity of amino acids and enzymes to catalyze the hydrolysis and condensation of tetraethoxysilane and phenyltrimethoxysilane. Selected amino acids were shown to accelerate the hydrolysis and condensation of tetraethoxysilane under ambient temperature, pressure and at neutral pH (pH 7±0.02). The nature of the side chain of the amino acid was important in promoting hydrolysis and condensation. Several proteases were shown to have a capacity to hydrolyze tri- and tet-ra- alkoxysilanes under the same mild reaction conditions. The second part of this thesis employed an immobilized Candida antarctica lipase B (Novozym-435, N435) to produce siloxane-containing polyesters, polyamides, and polyester amides under solvent-free conditions. Enzymatic activity was shown to be temperature dependent, increasing until enzyme denaturation became the dominant pro-cess, which typically occurred between 120-130ᵒC. The residual activity of N435 was, on average, greater than 90%, when used in the synthesis of disiloxane-containing polyesters, regardless of the polymerization temperature except at the very highest temperatures, 140-150ᵒC. A study of the thermal tolerance of N435 determined that, over ten reaction cycles, there was a decrease in the initial rate of polymerization with each consecutive use of the catalyst. No change in the degree of monomer conversion after a 24 hour reaction cycle was found.

Influence of functional groups of activated carbon in the anchoring of iron particles by forced hydrolysis and its use to remove hexavalent chromiun from aqueous solutions.

Tesis (Master of Science with orientation in Sustainable Processes) UANL, 2014.

Preparation of high surface area TiO (anatase) by thermal hydrolysis 2 of titanyl sulphate solution

Highly crystalline, ultra fine TiO (anatase) having high surface area has been prepared by thermal hydrolysis of titanyl sulphate 2 solution and characterized using B.E.T surface area measurements, XRD and chemical analysis. The dependence of surface area on concentration of staffing solution, temperature of hydrolysis, duration of boiling and calcination temperature were also studied. As the boiling temperature, duration of boiling and calcination temperature increased, the surface area of TiO formed decreased significantly. 2 On increasing calcination temperature, the crystallite size of TiO also increased and gradually the phase transformation to rutile took 2 place. The onset and completion temperatures of rutilation were 700 and 10008C, respectively

Glucoamylase immobilized on montmorillonite: Synthesis, characterization and starch hydrolysis activity in a fixed bed reactor

Glucoamylase from Aspergillus Niger was immobilized on montmorillonite clay (K-10) by two procedures, adsorption and covalent binding. The immobilized enzymes were characterized using XRD, surface area measurements and 27Al MAS NMR and the activity of the immobilized enzymes for starch hydrolysis was tested in a fixed bed reactor (FBR). XRD shows that enzyme intercalates into the inter-lamellar space of the clay matrix with a layer expansion up to 2.25 nm. Covalently bound glucoamylase demonstrates a sharp decrease in surface area and pore volume that suggests binding of the enzyme at the pore entrance. NMR studies reveal the involvement of octahedral and tetrahedral Al during immobilization. The performance characteristics in FBR were evaluated. Effectiveness factor (η) for FBR is greater than unity demonstrating that activity of enzyme is more than that of the free enzyme. The Michaelis constant (Km) for covalently bound glucoamylase was lower than that for free enzyme, i.e., the affinity for substrate improves upon immobilization. This shows that diffusional effects are completely eliminated in the FBR. Both immobilized systems showed almost 100% initial activity after 96 h of continuous operation. Covalent binding demonstrated better operational stability.

Hydrolysis of N2O5 on submicron sulfuric acid aerosols

The kinetics of reactive uptake of gaseous N2O5 on submicron sulfuric acid aerosol particles has been investigated using a laminar flow reactor coupled with a differential mobility analyzer (DMA) to characterize the aerosol. The particles were generated by homogeneous nucleation of SO3/H2O mixtures. In the H2SO4 concentration range 26.3−64.5 wt % the uptake coefficient was γ = 0.033 ± 0.004, independent of acid strength. For an acid strength of 45 wt % γ was found to decrease with increasing temperature over the range 263−298 K. From this, temperature dependence values of −115 ± 30 kJ/mol and −25.5 ± 8.4 J/K mol were determined for the changes in enthalpy and entropy of the uptake process, respectively. The results are consistent with a previous model of N2O5 hydrolysis involving both a direct and an acid catalyzed mechanism, with uptake under the experimental conditions limited by mass accommodation.