Color,trypsin inhibitor and urease activity as it affects growth of broilers

In five experiments, the relationships among trypsin inhibitor contents, urease index and color in soybean meal (SBM), and the effects of those relationships on broiler chick performance were determined. Raw, solvent-extracted SBM was dehydrated to 2% moisture; then 0, 4, 8, 12, or 16% moisture was added and autoclaved at 120 C in sealed containers from 0 to 135 min with 15-min intervals. Urease and trypsin inhibitor contents decreased with either increasing moisture content or cooking time. With 16% added moisture, 30 min of cooking time was required to decrease urease index to an acceptable level, and 45 min was required to decrease trypsin inhibitor contents. Raw SBM autoclaved with less than 12% added moisture contained urease and trypsin-inhibitor contents that were not considered undesirable, regardless of cooking time used. Increased moisture and cooking time resulted in decreased trypsin inhibitor and urease contents, increased broiler growth, improved feed efficiency and decreased pancreas hypertrophy. Commercial SBM, containing 12 ug trypsin inhibited per mg of protein (μ/mg), a tristimulus+α (redness) color value of +3.21, and a urease index of 0.19 ΔpH, was autoclaved for 0–25 min with 5-min intervals to determine the effect of additional heat on broiler performance and SBM color. The commercial SBM, heated an additional 10 min, contained 1.77 μg trypgin inhibitor per mg of protein, a+a color value of +4.76, and urease index of 0.02 ΔpH. Broiler growth and feed efficiency were improved when the commercial SBM was heated an additional 10 min. Results of this study show that color is a good predictor of trypsin-inhibitor content and broiler chick performance. Color may be used to predict underprocessing, adequate, and overprocessing of SBM; however, trypsin inhibitor and urease index do not show the effect of overprocessing.     

Selection of parameters for thermal treatment of soybeans by enzyme inactivation

The effects of thermal treatment, dry heat and steam on the physiologically active substances: urease and trypsin inhibitors of soybean products, were evaluated by means of urease activity and trypsin inhibitor activity. The parameters time and temperature, moisture and particle size were considered. From these analyses it can be concluded that the best conditions to obtain optimum soybean products were 25% of initial moisture content, exposed to steam (97 degrees C) during four to eight minutes.     

Urease immobilized on chitosan membrane: Preparation and properties

Urease was covalently immobilized on glutaraldehyde-pretreated chitosan membranes. The optimum immobilization conditions were determined with respect to glutaraldehyde pretreatment of membranes and to reaction of glutaraldehyde-pretreated membranes with urease. The immobilized enzyme retained 94% of its original activity. The properties of free and immobilized urease were compared. The Michaelis constant was about five times higher for immobilized urease than for the free enzyme, while the maximum reaction rate was lower for the immobilized enzyme. The stability of urease at low pH values was improved by immobilization; temperature stability was also improved. The optimum temperature was determined to be 65°C for the free urease and 75°C for the immobilized form. The immobilized enzyme had good storage and operational stability and good reusability, properties that offer potential for practical application.     

Influence of carbonization conditions and wood species on carbon dioxide reactivity of resultant wood char powder

Carbon dioxide reactivities of powdered samples of Acacia and Eucalyptus wood chars were measured thermogravimetrically at 900°C and the effects of carbonization conditions (temperature, heating rate and soaking time) and wood species were determined. The results showed that the reactivity decreased with increasing carbonization temperature and soaking time. Chars prepared under rapid carbonization (heating rate: 30°C min⁻¹) were found to be more reactive than the chars produced by slow carbonization (heating rate: 4°C min⁻¹). In comparison to Eucalyptus wood chars, the Acacia wood chars exhibited higher reactivity.     

Retention and reusability of trypsin activity by covalent immobilization onto grafted polyethylene plates

This study investigated the activity of trypsin that had been covalently immobilized onto acrylic acid (AA)– and methacrylic acid (MAA)–grafted polyethylene (PE) plates—PE–g–PAA and PE–g–PMAA—using a water‐soluble carbodiimide as a coupling agent, as a function of the immobilized amount, the grafted amount, the pH value on immobilization, and the pH value and temperature at the activity measurement. The activity of trypsin immobilized on the PE–g–PAA plates at pH 6.0 decreased with an increase in the immobilized amount because of the crowding of trypsin molecules in the vicinity of the surfaces of the grafted PAA layers. The increase in the grafted amount resulted in a decrease in the activity of immobilized trypsin because of a decrease in the diffusivity of BANA molecules caused by the formation of dense grafted PAA layers for the PE–g–PAA plates and led to the increased activity because of the increase in the hydrophilicity of the whole grafted layers for the PE–g–PMAA plates. The activity of trypsin immobilized on the PE–g–PAA and PE–g–PMAA plates at pH 6 increased with an increase in the pH value, probably because of the expansion of trypsin‐carrying grafted PAA and PMAA chains and the increased diffusivity of Nα‐benzoyl‐DL ‐arginine‐nitroanilide hydrochloride molecules in the grafted layers. The optimum temperature of the activity of immobilized trypsin shifted to 50°C from 30°C for native trypsin. Immobilized trypsin was reusable without any denaturation and isolation at temperatures ranging from 20°C to 60°C and pH values ranging from 6 to 10. Trypsin immobilized on a PE–g–PAA plate had 95% of the remaining activity in relation to native trypsin at 30°C after preservation in a pH 7.8 buffer at 4°C over 6 months. These results made clear that alkaline and thermal stability, reusability, and storage stability can be much improved by the covalent coupling of trypsin on PE–g–PAA and PE–g–PMAA plates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3574–3581, 2003     

Retention of activity of urease immobilized on grafted polymer films

Expanded poly(tetrafluoroethylene) (ePTFE) films grafted with 2‐hydroxyethyl methacrylate (HEMA) and 2‐hydroxyethyl acrylate (HEA) were applied to a polymer support for urease immobilization. The HEMA‐ and HEA‐grafted ePTFE (ePTFE‐g‐PHEMA and ePTFE‐g‐PHEA) films prepared by the combined use of the plasma treatment and photografting possessed high water‐absorptivities. Imidazole groups were introduced to grafted PHEMA and PHEA chains with 1,1′‐carbonyldiimidazole (CDI) in acetonitrile. The activity of urease covalently immobilized to the ePTFE‐g‐PHEMA and ePTFE‐g‐PHEA films in a pH 7.0 buffer at 4°C had the maximum value at the optimum pH value of 7.5 for native urease. Urease immobilized on the ePTFE‐g‐PHEMA films with the extent of CDI bonding of about 20% had the maximum activity, and the repeatedly measured activity was kept almost constant. The relative activity of immobilized urease stayed almost constant in the range of the immobilized amounts between 10 and 30 mg/g for both grafted ePTFE films, and decreased at higher immobilized amounts because of the crowding of immobilized urease molecules in the grafted layers. The relative activity of immobilized urease had the maximum values at the grafted amounts of 1.2 and 1.7 mmol/g for the ePTFE‐g‐PHEMA and ePTFE‐g‐PHEA films, respectively, and the further increase in the grafted amount resulted in the decrease in the relative activity. The optimum temperature of the activity for immobilized urease was shifted from 30 to 50°C for native urease by the covalent immobilization on both grafted ePTFE films and immobilized urease was repeatedly usable without a considerable decrease in the activity in the regions of the pH 6.0–9.0 and 10–60°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4886–4896, 2006     

Effects of water sorption at different temperatures on permanent changes in an epoxy

Crosslinked epoxy resins, tetraglycidyl 4,4′-diamino diphenyl methane cured with 4,4′-diamino diphenyl sulfone, were soaked in water at either 25°C or 70°C for varying lengths of time. The infrared spectra and DSC thermograms were obtained for samples that were soaked, or soaked and dried. There was a monotonic decrease in exothermic reaction energy with water content. The glass transition was also lowered, although samples soaked at 70°C showed a leveling in the T_g around 115°C. When the soaked samples were dried, the exothermic reaction energy showed near reversibility for samples soaked at 25°C while the 70°C samples were highly irreversible. IR of the latter samples showed that the 70°C water soaking resulted in reaction of some of the unreacted epoxide groups that remained after the initial cure.     

The Diffusion of Moisture in Paddy During Hydration and Dehydration Processes

Hydration and dehydration behavior and the effective diffusivity of paddy during the process of parboiling were studied. Hydration of three different paddy samples (Sherpa low and high head rice yield and Reiziq) were performed below (60°C) and above (90°C) the gelatinization temperature. The hydration period ranged from 5 to 300 minutes at 60°C and 5 to 90 minutes at 90°C. All of the paddy samples showed different hydration behavior below and above the gelatinization temperature, discerned with two different stages at 60°C and three stages at 90°C. Dehydration was carried out at 40°C just after hydration (without tempering the kernel), which mostly took place at the falling rate period. The hydration and dehydration pattern was not different between the high HRY and low HRY paddy, indicating a limited contribution of microfissures to the diffusion rate in the paddy. Five commonly used semi-empirical models were used to predict the hydration and dehydration behavior of paddy and, among them, the Page model was found to be the most suitable. The effective diffusivity during hydration was dependent on the temperature of hydration, which was 1.83 × 10^?11 to 2.11 × 10^?11 m²/s at 60°C and 6.68 × 10^?11 to 7.94 × 10^?11 m²/s at 90°C. The effective diffusivity during dehydration depended on the soaking temperature and period of soaking; it was lower for high-temperature-hydrated samples than low-temperature-hydrated samples. The study concluded that the mass water diffusivity was not affected by the microfissures within the paddy kernel, and the hydration pattern was strongly dependent on whether the temperature was above or below the gelatinization temperature.     

Degradation of Poly(L-lactide) Films under Ultraviolet Irradiation and Water Bath

Poly(L-lactide) (PLLA) films were exposed to ultraviolet (UV) light (254 nm) and water bath of 60°C and 80°C. The limiting viscosity ([η]) of PLLA decreased from initial 187.4 dl/g to 42.2 dl/g after UV irradiation, and to 33.3 dl/g after soaking in 80°C water for 40 h, while the [η] of PLLA exposed to 60°C water remained at 115.6 dl/g after 40 h. Compared with the original PLLA, the degraded PLLA was bimodal in the GPC profile. FTIR analysis showed that the chain scission of PLLA acted by water molecules resulted in a C=C structure.     

Inhibition of activity of urease in native form and immobilized on chitosan membrane by sodium fluoride

The influence of sodium fluoride inhibitor on the activity of urease in native form and immobilized covalently on glutaraldehyde-pretreated chitosan membrane was studied. Initially, in the presence of fluoride ions (I), a complex EI is formed which undergoes slow isomerization into a secondary form EI*. Both stages are represented on the progress curves. The dissociation constant of EI, K_i, for native and bonded urease were determined. The apparent rate constant as a function of the initial urea concentration for a given fluoride ion concentration was calculated, k = k ([I], [S]). It was found that sodium fluoride is a competitive slow-binding inhibitor of urease. Hydrolysis of urea in the standard conditions, at pH = 7.0, at 25° and a constant ionic strength and variable concentrations of substrate and of inhibitor has been studied. The reaction was initiated by addition of enzyme and was observed over a period of 10 min. The rate of hydrolysis at any point of time for both forms of urease, free and bound, may be calculated from the inhibition constants K_i, K*_i and apparent rate constant, k. It was found that immobilized urease is more resistant to the action of the inhibitor than the native one. This property offers potential for practical application.     

A Novel Immobilization Method of Urease in Silk Fibroin Scaffolds by Annealing at Constant Temperature and Humidity

Temperature and humidity (TH) post-treatment is a relatively mild way to change the silk fibroin (SF) secondary structure. Here, urease is immobilized in SF scaffold (SFS) by TH post-treatment, and the effects of annealing on the immobilized urease activity are examined. Fourier transform infrared indicates that the SFS secondary structure started to transform when the scaffold is annealed at 35 °C with 100% relative humidity for 20 min. The higher the temperature, the lower the treatment time is required to change SFS structure. Compared to methanol annealing, TH post-treatment maintains the original form of the sample, and the scaffold shows better water-binding abilities. The maximum recovery ratio of immobilized urease is 98.4 ± 7.0%, which is obtained after the scaffold is postprocessed at 35 °C for 60 min, and the relative recovery ratio of the urease activity is still as high as 80.6 ± 12.1% after repeatedly measuring 10 times. In addition, the relative recovery ratio of urease is not significantly decrease within 4 weeks of storage. Therefore, TH annealing is a relatively mild and effective way to immobilize urease in SFS. The urease-immobilized SFS with hydrophilic properties and prolonged enzyme activity may be used for peritoneal dialysate regeneration systems.     

Urease activity in soybean meal products

Summary A method which uses direct titration of ammonia as a measure of urease activity was modified for use in the assay of raw and of slightly denatured soybean meal. The modifications which were adopted were the use of glutathione, a presoaking of the sample for 30 min. at 40°C., and making of the assay at 40°C. Data on the urease activity of several varieties of soybeans, and for immature and frost-damaged soybeans were determined. Presented at the meeting of The American Oil Chemists’ Society, Houston, Tex., Apr. 23–25, 1956. In military service. One of the Branches of the Agricultural Research Service, U. S. Department of Agriculture.     

Chemical inactivation of soybean protease inhibitors

This study aimed to optimize chemical treatments to destroy Kunitz (KTI) and Bowman- Birk (BBI) type protease inhibitors in model systems, and to destroy total trypsin inhibitor activity in soy flour. Time, temperature, and reagent concentration were studied and 40 to more than 85% inactivation of KTI and BBI were observed by treatment with 0.6 mM Na₂S₂O₅,10 mM ascorbic acid + 0.8 mM CuSO₄ or 20 mM H₂O₂ + 0.8 mM CuSO₄ at 65- 90°C for 0.5- 1 hr. Upon treatment with Na₂S₂O₅, KTI and BBI amino acid composition had no significant change. In contrast, AH + CU²⁺ treatment of both KTI and BBI markedly increased aspartic acid + asparagine and glutamic acid + glutamine contents, and significantly decreased histidine, tyrosine, and methionine. With soy flour, only Na₂S₂O₅ effectively inactivated both protease inhibitors. Steeping soybean flour in 50 mM Na₂S₂O₅ at 65°C for 1 hr inactivated about 98% BBI and 95% KTI. The information conveyed is basic to developing chemical methodology needed to inactivate both KTI and BBI protease inhibitors in soy protein products. ¹Presented at the 1990 AOCS Annual Meeting, April 22–26, 1990, Baltimore, MD. ²The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Hydrated aluminium sulfate precipitation by enzyme-catalysed urea decomposition

Hydrated basic aluminium hydroxide precipitates were obtained from aluminium sulphate solution at room temperature and at 92°C by using urea. Enzyme urease was used to decompose urea at room temperature. It was observed that precipitates obtained at room temperature were much finer than those obtained at 92°C but they had similar chemistry. On calcination at 1200°C, each precipitate obtained at room temperature converted to a discrete α-Al₂O₃ crystal whereas that obtained at 92°C converted to a rather densely packed agglomerate of α-Al₂O₃ crystals. As a result of this, α-Al₂O₃ powder obtained from 25°C precipitates showed much better sintering behaviour.     

Walnut structure and its influence on the hydration and drying characteristics

Abstract

Fresh harvested walnuts are dehulled, washed, and then dried by hot air (HA) as a continuous process in the industry. The objective of the current work was to study the walnut structure and investigate its effect on the moisture transfer characteristics during the walnut soaking and drying processes. Moisture transport pathways into the walnuts were determined using fluorescence tracer approach, and the hydration kinetics of walnuts under different soaking temperatures (15, 25, and 35?°C) was studied using Peleg model. HA drying experiments in single layer in a self-designed automatic HA dryer at 43?°C and air velocity of 1.41?m/s. The influence of the stem pore (sealed and non-sealed) and the soaking process (0, 2- and 5-min soaking time) on the walnut drying characteristics were investigated systematically. The results indicated that both the presence of the stem pore and the soaking time had significant influence (p < 0.05) on the hydration and drying characteristics of walnuts. Moisture absorptions through the stem pore and the shell were equally important during the soaking process. Two to five minutes soaking process led to 2–4?h additional drying time. This study contributed valuable knowledge for the simulation and prediction of moisture transfer characteristics during the walnut soaking and drying processes. The findings from this study could potentially be applied to the walnut drying industry for more efficient processing     

The Development of Ginger Drying Using Tray Drying,Heat Pump–Dehumidified Drying,and Mixed-Mode Solar Drying

Mature ginger was pretreated by soaking in citric acid prior to drying in a single layer in a tray and heat pump dehumidified dryer at three temperatures of 40, 50, and 60°C and in a mixed-mode solar dryer at 62.82°C and a radiation intensity of 678 W/m². The drying data were applied to the modified Page model. Diffusivities were also determined using the drying data. Quality evaluation by color values, reabsorption, and 6-gingerol content showed best quality for ginger with no predrying treatment and dried at 40°C in a heat pump–dehumidified dryer. At drying temperature of 60 to 62.82°C, no pretreated dried ginger from mixed-mode solar dryer provided the shortest drying time and retained 6-gingerol as high as heat pump–dehumidified dryer.     

Urease immobilization on an ion‐exchange textile for urea hydrolysis

Ion‐exchange textiles are used as organic supports for urease immobilization with the aim of developing reactive fibrous materials able to promote urea removal. A non‐woven, polypropylene‐based cation‐exchange textile was prepared using UV‐induced graft polymerization. Urease was covalently immobilized onto the cation‐exchange textile using three different coupling agents: N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride (EDC), N‐cyclohexyl‐N′‐(b‐[N‐methylmorpholino]ethyl)carbodiimide p‐toluenesulfonate (CMC), and glutaraldehyde (GA). The immobilized biocatalyst was characterized by means of FT‐IR spectrometry, SEM micrographs, dependence of the enzyme activity on pH and temperature, and according to the kinetic constants of the free and immobilized ureases. The biotextile prepared with EDC in the presence of N‐hydroxysuccinimide performs best. The optimum pH was 7.2 for the free urease and 7.6 for the immobilized ureases. The reactivity was maximal at 45 °C for free urease, 50 °C for biotextiles prepared using EDC or CMC, and 55 °C for biotextiles prepared with GA. The activation energy for the immobilized ureases was 4.73–5.67 kcal mol^?1, which is somewhat higher than 4.3 kcal mol^?1 for free urease. The urea conversion for a continuous‐flow immobilized urease reactor is nearly as good as a continuously stirred tank reactor having a much longer residence time, suggesting that the packed bed reactor had sufficient diffusive mixing and residence time to reach nearly optimal results. Urease immobilized on a biotextile using EDC has good storage and operational stability. Copyright © 2006 Society of Chemical Industry     

Urease immobilized on aminated butyl acrylate-ethylenedimethacrylate copolymer

Urease was covalently immobilized on a new acrylic enzyme carrier: aminated butyl acrylate-ethylenedimethacrylate copolymer. The enzyme retained 56% of its original activity. The properties of the free and immobilized urease were determined and compared. The Michaelis constant was found to be higher for the immobilized urease than for the free one, while maximum reaction rate was lower for the immobilized enzyme. The stability of urease against change in pH was considerably improved by the immobilization. The immobilized urease showed very good storage stability and reusability. Resistance of the enzyme against heat inactivation at 70°C, however, was not found to be improved.     

Hydrothermal nucleation of hydroxyapatite on titanium surface

Titanium plates were submitted to nucleation and growth of hydroxyapatite (HAp) under hydrothermal conditions. A group of these plates were submitted to nucleation without any previous treatment and another group was treated with NaOH 1 M at 130°C inside an autoclave followed by heat-treatment at 600°C. The nucleation were performed by soaking all these titanium pieces, in a simulated body fluid (SBF) solution, containing calcium, phosphate and other ions, in order to promote the nucleation and growth of hydroxyapatite under hydrothermal conditions on the titanium surface. The results show that hydrothermal nucleation and growth of HAp occurs even on the non-treated titanium surface at 150°C. However, a better uniformity of the hydroxyapatite layer was observed on the pre-treated titanium surface, at 80°C, with the renewal of the SBF solution.     

Effect of Low Temperature-Long Time Blanching on Quality of Dried Sweet Potato

ABSTRACT

Combining low temperature, long time blanching with moderate temperature drying very positively affected the textural characteristics of dehydrated sweet potato. Ten mm cubes of this tuber were slow-blanched at 60, 65 and 70°C for 15 and 45 minutes, then conventionally blanched at 94°C three minutes and, finally dehydrated in a cabinet dryer at 70 and 8S°C for a maximum of 195 minutes. The final product showed optimum texture attributes for the blanching treatment of 65°C for 15 minutes followed by the flash blanching and the drying process at 70°C for 120 minutes.