Physico-chemical properties of flour and starch from jackfruit seeds (Artocarpus heterophyllus Lam.) compared with modified starches

Jackfruit (Artocarpus heterophyllus Lam.) is one of the most popular tropical fruits grown in Asia. The objective of this study was to compare physico‐chemical properties of native flour and starch from jackfruit seeds (A. heterophyllus) to commercially modified starches (Novation 2300 and Purity 4). The colour of jackfruit seed starch was lighter than the Novation 2300 starch but darker than the Purity 4 starch. The jackfruit seed starch had a narrower gelatinization temperature range than Purity 4 and required less gelatinization energy compared with modified starches. The peak viscosity of jackfruit seed starch was lower than commercially modified starches. Likewise, setback viscosity, swelling power and solubility of jackfruit seed starch showed similar trends. Results from this study suggest that native starch from jackfruit seed could be used as an alternative for modified starches in a system needing starch with a high thermal and/or mechanical shear stability.     

Photocatalytic activity of TiO2 coated porous silica beads on degradation of cumene hydroperoxide

Recently, due to an increasing global concern on environmental safety, titanium dioxide (TiO₂) photocatalyst has been extensively researched for use as air and water pollution treatments. This study was initiative for producing an economically viable TiO₂ photocatalyst material with recyclability for degradation of CHP contaminated wastewater. TiO₂ P‐25, a well‐known photocatalyst, with a proper amount (15% w/w of CAC) was coated on porous silica beads (ECOLITE^®) by granulation technique, using high calcium aluminate cement (CAC) as a binder (EC+CAC+15% w/w TiO₂ P‐25). The experiments revealed that high concentration CHP solutions were completely degraded by EC+CAC+15% w/w TiO₂ P‐25 within 5 and 7 hours. The recyclability of EC+CAC+15% w/w TiO₂ P‐25 was evaluated by investigation the degradation activity of freshly prepared CHP solution under UV light irradiation using the repetitive photocatalyst beads for 6 runs. HPLC analyses indicated that the CHP degradation was completed in the 1^st run and down to over 90% in the 6^th run. Hence, EC+CAC+15% w/w TiO₂ P‐25 showed a long durability and good recyclability for CHP degradation, resulted from the good adherence of hydration product layer of CAC for TiO₂ particles as well as its large surface area that offered good adsorption for CHP.     

Physicochemical properties of pectins from okra (Abelmoschus esculentus (L.) Moench)

Okra pectin obtained by hot buffer extraction (HBSS) consists of an unusual pectic rhamnogalacturonan I structure in which acetyl groups and alpha galactose residues are substituted on rhamnose residues within the backbone. The okra Chelating agent Soluble Solids (CHSS) pectin consists of slightly different structures since relatively more homogalacturonan is present within the macromolecule and the rhamnogalacturonan I segments carry slightly longer side chains. The rheological properties of both okra pectins were examined under various conditions in order to understand the unusual slimy behaviour of okra pectins. The viscosity of the okra HBSS pectin was 5–8 times higher than the viscosity of the okra CHSS pectin. The okra HBSS pectin showed an elastic behaviour (G′ > G″) over a wide range of frequencies (10⁻¹–10 Hz), at a strain of 10%, while okra CHSS and saponified okra HBSS/CHSS pectin showed predominantly viscous responses (G′ < G″) over the same frequency range. The results suggest that the structural variation within the okra pectins greatly affect their rheological behaviour and it is suggested that acetylation of the pectin plays an important role through hydrophobic associations. Dynamic light scattering was used to study the association behaviour of both okra pectins at low concentration (0.001–0.1% w/w). Results showed that the saponified okra pectins did not exhibit a tendency to aggregate in the concentration range studied, whereas both non saponified samples showed a substantial degree of association. These results suggest that the unusual slimy behaviour of the non saponified samples may be related to the tendency of these pectins to associate, driven by hydrophobic interactions.     

Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties

Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO₂ nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO₂ samples, and one commercial Degussa TiO₂ sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl₂) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO₂ isoelectric point was found to be dependent on particle size. As anatase TiO₂ primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO₂ nanoparticle IEP was found to be insensitive to particle crystal structure.     

Effect of Pt or Pd doping on stability of TiO2 nanoparticle suspension in water

Stability of suspensions of TiO₂ nanoparticles synthesized by the flame aerosol reactor (FLAR) could be altered by doping TiO₂ nanoparticles with Pt, Pd, or Pt–Pd dopants. It was found that doping of TiO₂ with Pd or Pt could contribute to the control of the agglomeration of TiO₂ suspended in water. With the change of doping content, the isoelectric point (IEP) of stable TiO₂ suspension decreased gradually from 5 to 3.6 while the specific surface area was increased from 43.27 to 60.84 m²/g. With pH > 6.0, 2 wt% Pt–Pd/TiO₂ suspension exhibited the lowest agglomeration behavior. The plausible intrinsic structures of Pt, Pd, and Pt–Pd doped TiO₂ nanoparticles were proposed and discussed with respect to their IEP based on the DLVO theory.     

Effect of Okra Cell Wall and Polysaccharide on Physical Properties and Stability of Ice Cream

Stabilizers are used in ice cream to increase mix viscosity, promote smooth texture, and improve frozen stability. In this study, the effects of varying concentrations (0.00%, 0.15%, 0.30%, and 0.45%) of okra cell wall (OKW) and its corresponding water‐soluble polysaccharide (OKP) on the physical characteristics of ice cream were determined. Ice cream mix viscosity was measured as well as overrun, meltdown, and consumer acceptability. Ice recrystallization was determined after ice cream was subjected to temperature cycling in the range of ?10 to ?20 °C for 10 cycles. Mix viscosity increased significantly as the concentrations of OKW and OKP increased. The addition of either OKW or OKP at 0.15% to 0.45% significantly improved the melting resistance of ice cream. OKW and OKP at 0.15% did not affect sensory perception score for flavor, texture, and overall liking of the ice cream. OKW and OKP (0.15%) reduced ice crystal growth to 107% and 87%, respectively, as compared to 132% for the control (0.00%). Thus, our results suggested the potential use of OKW and OKP at 0.15% as a stabilizer to control ice cream quality and retard ice recrystallization. OKP, however, at 0.15% exhibited greater effect on viscosity increase and on ice recrystallization inhibition than OKW.     

Characterization of doped TiO2 nanoparticle dispersions

Nanomaterial suspensions with different dopant types and compositions were investigated to examine their effects on agglomeration through the measurement of hydrodynamic diameter (HD), surface charge, and isoelectric point (IEP). Four different types of nanoparticles, all synthesized by a flame aerosol reactor, were considered for the analysis. The nanoparticles considered were pristine TiO₂, Cu–TiO₂, V–TiO₂, and Pt–TiO₂ with dopant concentrations ranging from 1 to 6 wt%. Measurements were conducted over a broad range of pH (3–11) and ionic strengths (0.001–0.1 M) to understand the roles of pH and ionic strength (IS) on dispersion characteristics. Calculations were made using the classical DLVO theory to explain the agglomeration behavior. The results indicate that dopant addition can change surface charge, hydrodynamic diameter, and shift the IEP to higher or lower pH than pristine TiO₂, depending on the type of dopant and composition. Vanadium and platinum doping shifted the IEP to lower pH values, whereas copper doping shifted it to higher pH values. For each of the nanoparticles considered, pH and IS were found to have significant effects on the surface charge and HD, which were also verified by calculation from DLVO theory.     

Use of Average Molecular Weights for Product Categories to Predict Freezing Characteristics of Foods

ABSTRACT:  In the design of food freezing process, food property parameters, initial freezing temperature ( T_Fi ), and frozen water fraction ( X_I ) are required. The predictive approaches of these 2 parameters have been developed based on mass fractions and molecular weights of specific food components such as proteins, carbohydrates, minerals, and acids/bases. In this study, the molecular weights of the key mineral and acid/base components were successfully represented using average molecular weights (     ) and 4  T_Fi  and  X_I  calculation approaches were proposed. Based on an analysis of 212 food products, the absolute differences (AD) between the experimental and predicted  T_Fi  values for the 4 approaches were small. The prediction for the food model category was excellent with average AD (     ) values as low as ± 0.03 °C. For the other food categories, the prediction efficiency was impressive with     values between ± 0.22 and ± 0.38 °C. The predicted relationship between temperature and  X_I  for all analyzed food products provided close agreements with experimental data.     

Whey protein-okra polysaccharide fraction blend edible films: tensile properties, water vapor permeability and oxygen permeability

BACKGROUND: A hot‐buffer‐soluble‐solid fraction (HBSS) and an alkaline‐soluble‐solid fraction (ASS) of okra polysaccharides (OKP) were obtained using sequential extraction. These fractions were combined with whey protein isolate (WPI) and glycerol (Gly) plasticizer to form blend edible films. Effects of OKP fraction and content on tensile properties, water vapor permeability (WVP) and oxygen permeability (OP) were determined. RESULTS: HBSS film had significantly higher percent elongation (%E) and lower elastic modulus (EM), WVP and OP than ASS film. Increasing HBSS or ASS content in blend films with WPI significantly reduced film tensile strength and EM and increased film %E and WVP. OP values for WPI–HBSS blend films were significantly lower than OP for WPI or HBSS film. WPI–HBSS and WPI–ASS blend films had lower WVP and OP than WPI films with equivalent tensile properties. CONCLUSIONS: WPI–HBSS blend films have higher WVP and lower OP than WPI film or HBSS film, indicating unique interactions between WPI and HBSS. Compared to WPI film, WPI–HBSS blend films have improved flexibility, stretchability and oxygen barrier. Different HBSS and ASS compositions and structures are responsible for property differences between HBSS and ASS films and between WPI–HBSS and WPI–ASS blend films. Copyright © 2010 Society of Chemical Industry     

A Novel Needle-Type SV-GMR Sensor for Biomedical Applications

Cancer is the most deadly disease in the world today. There is a variety of different treatment methods for cancer, including radiotherapy and chemotherapy with anticancer drugs that have been in use over a long period of time. Hyperthermia is one of the cancer treatment methods that utilizes the property that cancer cells are more sensitive to temperature than normal cells. The control of temperature is an important task in achieving success using this treatment method. This paper reports the development of a novel needle-type nanosensor based on the spin-valve giant magnetoresistive (SV-GMR) technique to measure the magnetic flux density inside the body via pricking the needle. The sensor has been fabricated. The modeling and experimental results of flux density measurement have been reported. From the information of flux density, the temperature rise can be estimated to permit the delivery of controlled heating to precisely defined locations in controlled hyperthermia cancer treatment. The actual experiment with human is under investigation