Improved Storage Stability Research Articles

Preparation of a Calcium Alginate-Coated Polypyrrole/Silver Nanocomposite for Site-Specific Immobilization of Polygalacturonase with High Reusability and Enhanced Stability

Polygalacturonase (PG) catalyses the hydrolysis of pectin substances and is commonly used in the textile and food industries. Herein, PG was purified from Arabian balsam using three techniques (ammonium sulfate precipitation, ion exchange chromatography, and gel filtration) with a recovery of 11.2% and tenfold purification. The molecular weight of the purified PG was estimated to be 75.5 kDa using a Sephadex G-150 column. To improve the stability and reusability of the purified enzyme, a novel method to immobilize PG through calcium alginate-coated polypyrrole/silver nanocomposite was described. The immobilized PG was characterized by FTIR, TGA, SEM, EDX, and Raman spectroscopy. The immobilization efficiency was 84.4%. Excellent long-term storage stability of the immobilized PG was demonstrated with 83% of the initial activity preserved after 60 days. The immobilized PG was highly reusable, showing high activity (91% and 68%) after five and ten cycles. The immobilized PG showed improved stability to temperature and pH relative to that of the free enzyme. The Km and Vmax were determined to be 0.368 mg/mL and 5.33 µmol/mL for the immobilized PG and 0.667 mg/mL and 7.38 µmol/mL for free PG, respectively. Improved storage stability, catalytic efficiency (Vmax/Km), and reusability of the immobilized PG make it ideal for biotechnological and industrial applications.

One-step bulk and surface co-modification of LiNi0.8Co0.15Al0.05O2 cathode material towards excellent long-term cyclability

In order to improve the cycling stability of nickel-rich LiNi0.8Co0.15Al0.05O2 (NCA) cathode material for lithium-ion battery applications, a sulfur-modified NCA cathode material with bulk and surface co-modification is prepared by sol−gel method through addition of a very small amount of lithium sulfide (Li2S) as the sulfur-containing additive, and characterized in comparison with the pristine NCA material. Physical characterizations reveal that during the calcination process, some of the introduced S2− enter the layered oxide lattice to replace oxygen, while some of the introduced S2− are oxidized into a thin layer of Li2SO4 coated on the surface of the primary nanoparticles of the layered oxide. Doping of sulfur anion in bulk phase obviously reduces the content of Ni2+ and the degree of cation mixing. The electrochemical results demonstrate that the co-modified material has excellent long-term cycling stability and obviously improved storage stability. For example, when it is repeatedly cycled at 1C rate for 1100 cycles, its specific capacity is decreased from 145.0 to 102.1 mAh g−1, with capacity retention of 70.4%. The significantly improved cyclability is attributed to the enhanced structural stability owing to the reduced cation mixing and the improved electrode/electrolyte interfacial stability due to the surface modification.

Preclinical Evaluation of 99mTc-ZHER2:41071, a Second-Generation Affibody-Based HER2-Visualizing Imaging Probe with a Low Renal Uptake.

Radionuclide imaging of HER2 expression in tumours may enable stratification of patients with breast, ovarian, and gastroesophageal cancers for HER2-targeting therapies. A first-generation HER2-binding affibody molecule [99mTc]Tc-ZHER2:V2 demonstrated favorable imaging properties in preclinical studies. Thereafter, the affibody scaffold has been extensively modified, which increased its melting point, improved storage stability, and increased hydrophilicity of the surface. In this study, a second-generation affibody molecule (designated ZHER2:41071) with a new improved scaffold has been prepared and characterized. HER2-binding, biodistribution, and tumour-targeting properties of [99mTc]Tc-labelled ZHER2:41071 were investigated. These properties were compared with properties of the first-generation affibody molecules, [99mTc]Tc-ZHER2:V2 and [99mTc]Tc-ZHER2:2395. [99mTc]Tc-ZHER2:41071 bound specifically to HER2 expressing cells with an affinity of 58 ± 2 pM. The renal uptake for [99mTc]Tc-ZHER2:41071 and [99mTc]Tc-ZHER2:V2 was 25–30 fold lower when compared with [99mTc]Tc-ZHER2:2395. The uptake in tumour and kidney for [99mTc]Tc-ZHER2:41071 and [99mTc]Tc-ZHER2:V2 in SKOV-3 xenografts was similar. In conclusion, an extensive re-engineering of the scaffold did not compromise imaging properties of the affibody molecule labelled with 99mTc using a GGGC chelator. The new probe, [99mTc]Tc-ZHER2:41071 provided the best tumour-to-blood ratio compared to HER2-imaging probes for single photon emission computed tomography (SPECT) described in the literature so far. [99mTc]Tc-ZHER2:41071 is a promising candidate for further clinical translation studies.

Evaluation and improvement of storage stability of astaxanthin isomers in oils and fats

Astaxanthin Z-isomers potentially have greater bioavailability and biological activity than (all-E)-astaxanthin. However, the stability of the Z-isomers is lower than the all-E-isomer, which is a serious problem affecting its practical use. In this study, we investigated the impacts of different suspension media (oils and fats) and additives on astaxanthin isomer stability and identified suitable ones for astaxanthin stabilization. The evaluations showed that several vegetable oils and antioxidants significantly improved astaxanthin isomer stability, e.g., when soybean and sunflower oils were used as the suspension medium, astaxanthin isomers were hardly degraded; however the total Z-isomer ratio decreased from ~80% to ~50% during 6-week storage at 30 °C. Moreover, it was revealed that (9Z)-astaxanthin showed higher stability than the 13Z- and 15Z-isomers. Hence, to maintain astaxanthin concentration and the Z-isomer ratio over long periods, it is important to use suitable suspension mediums and antioxidants, and select a Z-isomerization method that increases (9Z)-astaxanthin ratio.

A Critical Review on Potential Advancements of Nanostructured Lipid Carriers in Drug Delivery

Nanostructured Lipid Carriers (NLCs) are second generation solid lipid nanoparticles (SLN) comprising of biocompatible solid-lipid and liquid-lipid along with an emulsifier. It exhibits superiority over conventional colloidal delivery systems in terms of enhanced drug loading, improved storage stability, increased biocompatibility and bioavailability, which allows researchers to explore their utility as delivery systems for proteins and small molecules. This review aims at discussing NLCs in-depth with regards to their application as drug delivery vehicles. A comprehensive discussion about the structural make-up, production techniques, and physico-chemical characterization have been elaborated along with an emphasis on various routes of administration for NLC delivery like ocular, pulmonary, oral, parenteral, and topical. This review also sheds light on the utility of NLCs in the field of cosmeceutical and herbal therapies. All summarized information in this extensive review exemplifies assurance for NLCs to be used as novel therapeutics for multiple disorders and highlights the versatility of the carrier system in pharmaceutical technology.

Improvement in storage stability and resveratrol retention by fabrication of hollow zein-chitosan composite particles

Solid and hollow particles based on zein have been prepared for the encapsulation of bioactive components. Hollow particles have many advantages over their solid counterpart, due to increased surface area, low density, and sustained release, emerged as a promising delivery system for polyphenols. It is necessary to improve the stability of zein particles for the encapsulation of bioactive components. The current work aims to prepare hollow zein particles by employing chitosan coating and explore the potential of the composite particles for the encapsulation and protection of resveratrol, a natural polyphenol. Hollow zein (HZ) and zein-chitosan (HZ-CH) particles were characterized in terms of size, surface charge, morphological structure, particle yield and antioxidant activity. Encapsulation of resveratrol in the zein matrix was studied by the help of fluorescence, infrared and X-ray diffraction techniques. The composite particles were also subjected to storage and in vitro digestion. Particle yield was greater than 90% when the concentrations of chitosan were greater than 0.02%. HZ-CH particles were positively charged and bigger in size as compare to HZ particles. Resveratrol entrapment caused an apparent increase in the size of the particles. The highest encapsulation efficiency and loading capacity of resveratrol were 91% and 14% in the hydrophobic zein shell of HZ-CH particles, respectively. The chitosan coating improved the storage and digestion stability of resveratrol-loaded hollow zein particles and the storage stability of encapsulated resveratrol and exhibited a sustained in vitro release of resveratrol. Therefore, the hollow zein composite particles could be used as an efficient delivery system for resveratrol in the development of functional foods.

Solidification of self-emulsifying drug delivery systems (SEDDS): Impact on storage stability of a therapeutic protein

Four solidification methods for self-emulsifying drug delivery systems (SEDDS) were compared to evaluate the impact of solidification on storage stability of an incorporated protein.Papain was loaded in SEDDS via hydrophobic ion pairing (HIP). Liquid SEDDS (l-SEDDS) were either solidified by adsorption to solid excipients such as magnesium-aluminometasilicate via wet granulation (ssilica-SEDDS) and carbohydrates via lyophilisation (scarbo-SEDDS) or by incorporation of high-melting PEG-surfactants (sPEG-SEDDS) and triglycerides (soil-SEDDS) in SEDDS preconcentrates. L- and s-SEDDS were compared regarding intrinsic emulsion properties, solid-state form of papain, enzyme stability and activity during storage.HIP with deoxycholate showed a precipitation efficiency of 82% and papain maintained 90% of its initial activity. Incorporated papain was present in an amorphous state, confirming a molecular dispersion in all preconcentrates. In comparison to l-SEDDS each solidification method investigated improved the storage stability of incorporated papain. Neither precipitation nor phase separation was observed for s-SEDDS. sPEG-SEDDS demonstrated with 87.8% the highest enzymatic activity and displayed according to the following rank order: sPEG-SEDDS > soil-SEDDS > ssilica-SEDDS > scarbo-SEDDS > l-SEDDS the highest remaining papain activity after 30 days of storage. This work clearly demonstrates that solidified SEDDS can provide a significantly improved storage stability for therapeutic proteins compared to corresponding liquid formulations.

Improving enzyme activity, thermostability and storage stability of β-1,3-1,4-glucanase with poly-γ-glutamic acid produced by Bacillus sp. SJ-10

β-1,3-1,4-glucanase (BG) is an industrially important enzyme owing to its stringent specificity for β-glucan cleavage. In this study, poly-γ-glutamic acid (γ-PGA) was added to BG to investigate its effect on improving the activity and stability of the enzyme. The effect of γ-PGA was investigated by analyzing kinetic and thermodynamic parameters. Compared to control, significant differences (P < .05) in enzyme activity were observed when 1.0 %, 1.5 %, and 2.0 % γ-PGA was added, and the activities were increased 1.23 ± 0.05, 1.23 ± 0.07, and 1.31 ± 0.07-fold, respectively. Regarding thermostability, residual BG activity after a 1 h incubation at 60 °C was 12.53 ± 0.06 % without γ-PGA and 79.02 ± 5.76 % with 1% γ-PGA. The storage stability at 25 °C and 50 °C also increased when γ-PGA was present. The kinetics and thermodynamic investigations indicated that the increased activity and stability of BG when γ-PGA was added were due to increased values of the Vmax, Kcat, and activation energy for denaturation. The findings of this study suggest that adding γ-PGA to BG increases the application value of this enzyme in the food and feed industries.

Improving Storage Stability and Physicochemical Performance of Styrene-Butadiene-Styrene Asphalt Binder Modified with Nanosilica

Due to storage stability drawbacks of polymer-modified bitumen (PMB), this study investigated the storage stability and physicochemical performance of Styrene-Butadiene-Styrene (SBS) asphalt binders (herein PMB) modified with Silicone surface-treated nanosilica (SNS). Dosages 0% (control), 1.5%, 3% and 5% SNS powder were added to PMB to prepare modified binders. Hot storage, Viscosity, Multiple Stress Creep Recovery (MSCR), Scanning Electron Microscopy (SEM), Fluorescence Microscopy (FM), Linear Amplitude Sweep (LAS), Fourier Transform Infrared (FTIR), and Proton Nuclear Magnetic Resonance (1H-NMR) tests were conducted using modified binders. The study found that adding nanosilica powder to PMB improved storage stability, increased viscosity and complex modulus, and reduced rutting of binders. However, this bitumen modification was not beneficial to fatigue cracking. The performance improvement was because of the interaction between the polymer and nanosilica, creating a new polymer-nanosilica network which lowered the dynamics around the SNS particles, thereby reducing phase separation. Further, the Silicone Si–O–Si backbone bond present in SNS modified asphalt binder reduced temperature sensitivity thereby preventing thermal degradation at high storage temperature. Nanosilica modified binders presented well-dispersed nanosilica particles in the asphalt matrix. The modification mechanism was predominantly physical. Overall, the study concluded that nanosilica improves storage stability, rutting, and morphology of PMB binders.

Facile synthesis of microencapsulated 1-dodecanol/melamine-formaldehyde phase change material using in-situ polymerization for thermal energy storage

In this study, a new microencapsulated organic PCM (MicroPCM) was developed and its thermal energy storage (TES) properties were experimentally investigated. The microcapsules were prepared through a facile in-situ polymerization process using 1-dodecanol as the core PCM and the melamine-formaldehyde as the shell material. The microstructural analysis results infer that, the as-prepared microcapsules were spherical in shape, and the existence of carbon, oxygen and nitrogen elements have confirmed the effective formation of the MicroPCM. The average particle size (490.2 nm), surface roughness and with no chemical interaction between the core and the shell materials have paved way for achieving improved storage stability of the MicroPCM. The microcapsules with high thermal storage capability of 91.2 % have exhibited good latent heat of fusion of 79.45 kJ/kg. The microcapsules were thermally stable up to 132.82 °C, which was substantially higher than that of the operating temperature range of the pure PCM. The measured thermal conductivity of the MicroPCM was relatively lower (0.1727 W/m K) which has satisfied the thermal insulation criteria as well. The thermal cycling test conducted for microcapsules showed excellent thermal reliability (reliability index of 94.4 %). Also, no chemical interaction was observed between the core and the shell materials even after 200 heating/cooling process. Based on the test results, it is inferred that, the MicroPCM with enhanced properties can be a promising candidate for low temperature thermal energy storage.

Investigating the Rheological Properties of Carbon Nanotubes/Polymer Composites Modified Asphalt.

The utilization of nanomaterials in the field of binder materials for road paving has attracted researchers’ attention in recent years. This study presented the performance properties of a binder modified with carbon nanotubes (CNT) and polyethylene (PE). The rheological properties, adhesion behavior, morphology, and storage stability of the modified asphalt were investigated. Experimental analysis indicated a positive effect of CNT/PE composites on the performance of the binder. The results indicate that the combined use of CNT and PE shows a significant enhancement on complex modulus, viscosity, and creep recovery of the binder at high temperatures and a great decrease in compliance, indicating great resistance to permanent deformation. Meanwhile, only using CNT to improve the high temperature performance of the binder is limited due to high shear mixing. CNT/PE modifiers enhance the cracking resistance at low temperatures and moisture damage resistance. The CNT/PE melt mixing composites endow asphalt with stronger cracking resistance, better resistance to moisture damage and workability. Asphalt with CNT/PE composites formed an even dispersion system. Notably, CNT bridges on the interface between PE phase and asphalt for the two modified asphalts, which reinforces the cohesion of interface. Asphalt with CNT/PE composites showed improved storage stability in comparison with PE modified asphalt.

Rubber asphalt modified with waste cooking oil residue: Optimized preparation, rheological property, storage stability and aging characteristic

The poor storage stability of rubber asphalt induced by the incompatibility of the rubber-asphalt system still remains challenging although extensive researches have been performed. In this study, the waste cooking oil residue (WCOR) was used as a stabilizer to prepare a hot storage-stable rubber asphalt (HSSRA). The key preparation parameters in terms of WCOR content, mixing temperature and mixing time were optimized using an orthogonal test, and the resulting softening point difference value of HSSRA reached 0.3 ℃ at the optimum preparation condition. Chemical and molecular analysis via Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC), as well as phase morphology analysis via fluorescence microscopy (FM) showed that there was no chemical reaction between WCOR and rubber particles during the preparation process. The incorporation of WCOR in rubber asphalt promoted the swelling and decomposition of rubber particles, which led to the improved storage stability of HSSRA. Brookfield viscosity analysis proved that WCOR reduced the viscosity of HSSRA, thus lowering the mixing and compaction temperature. Rheological characterization via dynamic shear rheometer (DSR) and bending beam rheometer (BBR) revealed that the low-temperature performance of HSSRA was enhanced significantly compared with that of rubber asphalt, whereas the high-temperature stability of HSSRA was slightly reduced. Notably, the aging resistance of HSSRA was improved due to the effect of WCOR.

Screening acetylcholinesterase inhibitors from traditional Chinese medicines by paper-immobilized enzyme combined with capillary electrophoresis analysis

Discovering acetylcholinesterase (AChE) inhibitors is one of the important ways to develop new drugs for the treatment of Alzheimer's disease. In this work, a simple strategy was developed for screening AChE inhibitors from traditional Chinese medicines (TCMs) by capillary electrophoresis (CE) analysis combined with enzymatic assay, in which immobilized AChE was employed. For AChE immobilization, cellulose filter paper (CFP) was used as the carrier material and physically coated with chitosan owing to moderate viscosity of chitosan to be introduced into amino groups, and then AChE was covalently bonded to the amino-functionalized CFP through a Schiff base reaction using glutaraldehyde (GA) as a cross-linking agent. The CFP-immobilized AChE exhibited enhanced endurance to pH and temperature, improved storage stability, excellent repeatability and reusability. More remarkably, CFP-immobilized AChE can be instantly separated from enzyme reaction mixture thus greatly simplifying the operational process. For immobilized AChE, the Michaelis-Menten constant, inhibition constant and IC50 were determined using huperzine A as a model inhibitor. Finally, CFP-immobilized AChE was applied to inhibitor screening from 17 TCMs, among which Chebulae Fructus (ripe fruits of Terminalia chebula) exhibited the strongest inhibitory effect on AChE. The positive results indicated that such a screening strategy may open up a new avenue to discover active components from TCMs.

세포외 다당류를 생성하는 유산균 Weissella cibaria JNU29의 분리 및 특성과 이를 이용한 한국전통 설기떡 제조

Due to the nutritional value of rice cakes, there is renewed interest in this traditional Korean food, and thus various efforts have been made to improve its storage stability. In this study, lactic acid bacteria that produce exopolysaccharides (EPS) were isolated and their physiochemical properties were analyzed. The bacteria were used to produce ‘Sulgidduk’ (a Korean rice cake) with improved storage stability. Among the 107 strains isolated from traditional fermented foods, only five strains were confirmed to produce EPS in MRS media with 10% sucrose. Two of these strains were identified as members of the genus Weissella and three were identified as the Bacillus genus via sequence analysis of 16S rDNA. Among the five strains, the strain Weissella cibaria JNU29 was selected for application to ‘Sulgidduk’, since it is food applicable, viable in artificial gastric and bile juices, and produces the highest content of EPS (16.72 g/L). TLC and HPLC analysis showed that the EPS produced by W. cibaria JNU29 strain was a homopolysaccharide composed of only glucose. A culture solution of the W. cibaria JNU29 strain was mixed with milled rice flour to prepare ‘Sulgidduk’. After incubation for 48 h, the ‘Sulgidduk’ showed lower hardness values than that of the control without the culture solution, and the lactic acid bacteria survived to a level of 7 log CFU/g. Thus, the W. cibaria JNU29 strain, which produces EPS, can be applied for the production of ‘Sulgidduk’, as it delays retrogradation and prevents mold-induced decay to improve shelf life.

Sodium alginate coating pretreatment improved storage stability of heat pump dried scallop adductors: from thermal and thermodynamic points of view

Thermodynamic properties and glass transition temperature (Tg) of heat pump dried scallop adductors with (SA-C) and without (SA) sodium alginate coating pretreatment were investigated. Single sodium alginate film (SF) was also performed for comparison. The isotherms for SA, SA-C and SF followed type II characteristics. Water adsorption capacity of SA was decreased with coating pretreatment. The net isosteric heat of adsorption (qst) and differential entropy (Sd) were exponentially decreased with increasing moisture content (MC). Spreading pressure (φ) was increased with rising water activity (aw), but decreased with elevated temperature. Sodium alginate coating pretreatment decreased the qst, Sd and φ of SA. The enthalpy–entropy compensation theory can be employed for the adsorption behaviors of 3 samples. It was enthalpy-driven non-spontaneous for SA, and enthalpy-driven spontaneous for SA-C and SF, respectively. Based on the aw concept and glass transition theory, adsorption isotherm and Tg data were modeled and combined to establish state diagram. Compared with SA, the critical MC and aw were, respectively, increased 7.14% and 187.5% with coating pretreatment. Hydrocolloids coating is an innovative pretreatment in enhancing the storage stability of dried foods.

Evaluation and characterization of properties of crumb rubber/SBS modified asphalt

This research studies the effects of SBS copolymer and asphalt compositions on the properties of CR/SBS modified asphalts prepared by the terminal blend (TB) method. These CR/SBS modified asphalts, also called TB binders, were prepared by blending 20 wt% CR powders with two base asphalts and various amounts of SBS copolymers. The samples were subjected to conventional, rheological, force-ductility, rotational viscosity, thermal storage, and fluorescence microscopy tests. The results show that TB rubberized binders have superior properties to unmodified asphalts. The properties of TB rubberized asphalts were further improved by adding SBS copolymers, indicating that this is a feasible way to produce high-performance binders. However, the extent of improvement induced by SBS copolymer addition was less than that induced by CR addition. Activation energy (Ea) results suggest that this may be because the SBS copolymers do not form a polymer network structure throughout the asphalt. Moreover, the properties of TB binders are also affected by the asphalt composition. In terms of their stability index (SI) values, TB binders with various SBS contents showed good storage stability. Fluorescence observations revealed the state of rubber and SBS copolymer dispersion in the asphalt matrix, providing an explanation for the improved storage stability and confirming the deductions drawn from the Ea data. In conclusion, TB asphalt technology combined with SBS modification shows great potential to produce high-performance and cost-effective asphalt binders.

Investigation of the chemical, strength, adhesion and morphological properties of fly ash based geopolymer-modified bitumen

The current study seeks to investigate the chemical, strength, adhesion and morphological properties of fly-ash based geopolymer-modified bitumen (GMB). The geopolymer was prepared by mixing class F fly ash with alkaline solution (sodium silicate and sodium hydroxide), and was then mixed with an 80/100 penetration grade bitumen at different concentrations of 3, 5, 7 and 9% (by weight of bitumen) to produce the GMB. The chemical and strength properties of the binders were determined using the Fourier Transform Infrared Spectroscopy (FTIR) and Impact tests, respectively. The Surface Free Energy (SFE) and Atomic Force Microscope (AFM) tests were conducted to establish the adhesion and morphology of the binders. The modification of base bitumen with geopolymer resulting the improvement in structural chain mobility properties and improved storage stability compared to those of the control sample. The result of FTIR analysis showed that the incorporation of geopolymer into base bitumen did not cause any change in the functional groups, where the peaks of aromatic CC stretching is at around 1600 cm−1 (stretch), 1475 cm−1 (stretch) and 900–600 cm−1 (out-of-plane bend). The peak at around 1390 cm−1 clearly shows the stretch of the C-N amine group. The result of SFE test shows that GMB has better resistance to moisture damage. Finally, the AFM analysis revealed morphological changes in all GMB samples. In general, the addition of 5% geopolymer can be considered as is the optimum concentration for bitumen modification.

Preparation of a Copper Polyphosphate Kinase Hybrid Nanoflower and Its Application in ADP Regeneration from AMP.

In this research article, we reported a self-assembly approach to prepare a copper polyphosphate kinase 2 hybrid nanoflower and established a cofactor ADP regeneration system from AMP using the nanoflower. First, the structure of the hybrid nanoflower was confirmed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, which indicated the successful loading of the enzyme in the hybrid nanoflower. Moreover, compared to the free enzyme, the hybrid nanoflower exhibited a better performance in ADP production and possessed wider catalytic pH and temperature ranges as well as improved storage stability. The hybrid nanoflower also exhibited well reusability, preserving 71.7% of initial activity after being used for ten cycles. In addition, the phosphorylation of glucose was conducted by utilizing ADP-dependent glucokinase coupled with the ADP regeneration system, in which the hybrid nanoflower was used for regenerating ADP from AMP. It was observed that the ADP regeneration system operated effectively at a very small amount of AMP. Thus, the hybrid nanoflower had great application potential in industrial catalytic processes that were coupled with ADP-dependent enzymes.

Effect of natural preservatives on the organoleptic characteristics and storage stability of smoked &lt;i&gt;Heterotis niloticus&lt;/i&gt;

Improvement of consumer’s palatability of Heterotis niloticus was investigated by value addition with natural spices and salt to improve its palatability and shelf-life. The major problem of H. niloticus is its poor taste, hence low demand and poor consumer’s acceptability which affects the market value. The objective of this study was to improve the palatability and shelf-life of H. niloticus using selected natural spices. Heterotis niloticus, procured and treated with natural spices and salt were allowed to drain for one hour, subjected to charcoal fired smoking kiln for 12 hours, cooled and stored for 8 weeks at ambient temperature before microbial analysis. The result showed that treatment 1 had the best quality (37.7%), followed by control sample (34.7%), and treatment 2 (28.9%), while the least was treatment 3 (21.6%). Microbial analysis shows that no Salmonella, Coliforms and E. coli were detected from the samples after smoking. Staphylococcus aureus count ranged from 2 × 102 to 9 × 102 but it was not detected in treatment 1. Improvement of the consumers’ palatability of H. niloticus and improved storage stability by spicing methods improved the poor taste of H. niloticus which has been discriminated despites excellent muscle quality.&#x0D; Key words: Heterotis niloticus, organoleptic, spicing, microbial analysis

Alpha‐amylase immobilized on polycaprolactone‐grafted magnetic nanoparticles: improving stability and reusability

AbstractBACKGROUNDWidespread application of enzymes for research and industrial purposes is dependent on enhancing the catalytic capacity. One promising approach to this end is the immobilization of enzymes on novel nanomaterials. In this study, a novel nanocarrier was developed for the immobilization of enzyme on polycaprolactone (PCL)‐functionalized magnetic nanoparticles.RESULTStructural and physicochemical characterization of the PCL‐modified magnetic nanocarrier was achieved via Fourier‐transform infrared (FTIR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and vibration sample magnetometry (VSM). In order to determine the optimal conditions for immobilization, different parameters such as pH, temperature, reaction time and enzyme concentration were evaluated. Based on the results, the optimal biocatalytic activity of immobilized α‐amylase was obtained at 65 °C and pH 6.5. Under appropriate conditions, the immobilized α‐amylase showed improved storage stability in comparison with free one. Additionally, the reusability of the immobilized system demonstrated &gt;50% enzyme activity, at optimal pH and temperature, after five reaction cycles.CONCLUSIONThis finding could be useful in the application of immobilized enzymes for analytical purposes, industrial exploitations, biotechnology, biomedical engineering and other bio‐applications. © 2020 Society of Chemical Industry