Differentiation of Lard From Other Edible Fats and Oils by Means of Fourier Transform Infrared Spectroscopy and Chemometrics

Fourier transform infrared (FTIR) spectra at mid infrared regions (4,000–650 cm⁻¹) of lard and 16 edible fats and oils were compared and differentiated. The chemometrics of principal component analysis and cluster analysis (CA) was used for such differentiation using FTIR spectra intensities of evaluated fats and oils. With PCA, an “eigenvalue” of about 90% was achieved using four principal components (PCs) of variables (FTIR spectra absorbances at the selected frequency regions). PC1 accounted for 44.1% of the variation, while PC2 described 30.2% of the variation. The main frequency regions that influence the separation of lard from other evaluated fats and oils based on PC1 are 2,852.8 followed by 2,922 and 1,464.7 cm⁻¹. Furthermore, CA can classify lard into its group based on Euclidean distance.     

Interference of Saturated Fats in the Determination of Low Levels of <Emphasis Type="Italic">trans</Emphasis> Fats (below 0.5%) by Infrared Spectroscopy

The mandate to label food products with the content of total trans fatty acids has led to an increase in demand for sensitive and accurate methodologies for the rapid quantitation of trans fats. Unfortunately, the latest official infrared (IR) spectroscopic method lacks the required sensitivity. A more sensitive IR procedure that requires the measurement of the height of the second derivative (2D) of the trans absorption band at 966 cm⁻¹ was recently proposed; however, a reported inconsistency at low trans levels between GC (0% of total fat) and IR (1.2% of total fat) results for a fully hydrogenated vegetable oil could not be reconciled, and triggered further investigations. For the first time, we recognize and report the presence of weak interference bands (962–956 cm⁻¹) attributed to saturated fats in the IR spectra of trans fats; these interference bands have an adverse impact on the sensitivity and accuracy of the IR determination at low trans levels (≤0.5% of total fat). Therefore, weak spectral features observed at energies below the one expected for trans bands (966 cm⁻¹) in test samples high in saturated fat (coconut oil and cocoa butter) must not be mistaken for trans bands.     

A kinetic study on the electrodeposition of nickel nanostructure and its electrocatalytic activity for hydrogen evolution reaction

The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker’s equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni²⁺ concentration. Atomic force microscopy was used to confirm the presumed model. Also, the electrocatalytic activities of the Ni films were investigated for hydrogen evolution reaction (HER). The electrocatalytic activity of the Ni nanostructure was three times higher than the 2D Ni microstructure when the overpotential of −1.2 V was applied. The HER current density at −1.4 V for Ni nanostructure (−20 mA cm⁻²) was considerable with respect to the Ni microstructure (−8.46 mA cm⁻²) too.     

Evaluation of the role of saturated fatty acids in sedimenting canola oils

Canola oil is generally a clear oil which does not require winterization. However, sediment formation has become an increasing problem in Australian canola oil. Canola oil stored at temperatures between −5 and 21°C formed sediment more rapidly at lower temperatures. The sediment and clear fractions of a group of sedimenting canola oils were analyzed and compared. Both fractions contained wax esters of carbon number C42–C52, the sediment fractions containing between 0.37 and 3.09 mg g⁻¹ and clear fractions containing between 0.12 and 0.85 mg g⁻¹. The triacylglycerol profiles of sediment fractions contained four compounds, PPO, PPP, PSO and PPS (where P is palmitoyl, O is oleoyl, and S stearoyl), that were not detected in clear fractions. The contents of palmitic acid and total saturated fatty acids were higher in the sediment fraction than the clear fraction. Added PPP clouded a clear oil as effectively as stearyl behanate and more than OOO or lauryl arachidate. Sedimentation may be linked to environmental conditions, as seed grown in 1997, a dry year, produced more problem oils than seed grown in previous years that had more nearly average rainfall.     

Effect of enzymatic transesterification on the melting points of palm stearin-sunflower oil mixtures

Transesterification with lipases may be used to convert mixtures of fats to plastic fats, making them more suitable for use in edible products. In our study, 1,3-specific (Aspergillus niger, Mucor javanicus, Rhizomucor miehei, Rhizopus javanicus, and Rhizopus niveus) and nonspecific (Pseudomonas sp. and Candida rugosa) lipases were used to transesterify mixtures of palm stearin and sunflower oil (PS-SO) at a 40:60 ratio in a solvent-free medium. The transesterified mixtures of PS-SO were analyzed for their percentage free fatty acids (FFA), degree and rate of transesterification, solid fat content, slip melting point (SMP), and melting characteristics by differential scanning calorimetry. Results indicated that Pseudomonas sp. lipase produced the highest degree (77.3%) and rate (50.0 h⁻¹) of transesterification, followed by R. miehei lipase at 32.7% and 27.1 h⁻¹, respectively. The highest percentage FFA liberated was also in the reaction mixtures catalyzed by Pseudomonas sp. (2.5%) lipase and R. miehei (2.4%). Pseudomonas-catalyzed mixtures produced the biggest drop in SMP (13.5°C) and showed complete melting at below body temperature. All results indicated conversion of the PS-SO mixtures to a more fluid product. The findings also suggest that the specificity of lipases may not play a significant role in lowering the melting point of the PS-SO mixtures.     

Magneto-sensitive nickel nanowires fabricated by electrodeposition into multi- and single-ion track templates

Polycarbonate templates of (30±1) μm thickness containing cylindrical etched-track nanochannels of (500±50) nm diameter were used for electrodeposition of Ni nanowires. Using 10⁴ channels per cm², the most favourable deposition potential of  − 1.0 V was determined in a potentiostatic mode by varying the deposition potential with respect to an Ag/AgCl reference electrode over a range between  − 0.1 V and  − 1.5 V. The deposition efficiency at  − 1.0 V was estimated around 10%. The resulting single wires had a resistance around 200 Ω and showed an anisotropic magnetoresistance (AMR) effect of 1%, applicable to directionally sensitive magnetic field sensors.     

Definition of a model fat for crystallization-in-emulsion studies

Numerous food products are dispersed in droplet emulsions in which fat is partially crystallized. A model fat allowing the study of crystallization in emulsion, obtained by the mixing of two fats (one solid and one liquid at room temperature) with simple triacylglycerol (TG) composition, is defined and characterized. Cocoa butter (CB), a vegetable fat mainly composed of monounsaturated long-chain fatty acids (POP, POST, StOSt, where P=palmitic, O=oleic, St=stearic), and miglyol, a synthetic oil made from capric and caprylic fatty acids, were chosen, respectively. The thermal behaviors of CB, miglyol, and their mixtures are studied using high-sensitivity differential scanning calorimetry (DSC). The CB/miglyol ratio was optimized (i) in order to make stable emulsions as a function of time, (ii) so that the mixture displays several solid phases on cooling that result from CB polymorphism, and (iii) in order to keep, even at low temperature, a liquid moiety facilitating the phase transitions. The CB 75%/miglyol 25% composition is defined as the model mixture. This mixture is characterized on cooling at 0.5°C/min by coupled X-ray diffraction as a function of temperature and DSC experiments. First and α 2L (49.3 Å) variety is formed. Then, co-crystallization of both CB and miglyol TG shows the simultaneous formation of longitudinal stackings of 44.5 and 34.5 Å with a lateral organization of β′ form. An unusual TG packing corresponding to compound formation is proposed to explain the observation of a 34.5 Å long-spacing. The crystallization behavior of the model fat mixture dispersed in emulsion droplets is also monitored in order to validate its use.     

Determination of cadmium (II) using H<Subscript>2</Subscript>O<Subscript>2</Subscript>-oxidized activated carbon modified electrode

Pristine activated carbon (AcC) was oxidized by H₂O₂ under ultrasonic conditions. Compared with pristine AcC, the H₂O₂-oxidized AC possesses higher accumulation ability to trace levels of Cd²⁺. Based on this, a highly sensitive, simple and rapid electrochemical method was developed for the determination of Cd²⁺. In 0.01 mol L⁻¹ HClO₄ solution, Cd²⁺ was effectively accumulated at the surface of H₂O₂-oxidized AcC modified paste electrode, and then reduced to Cd under −1.10 V. During the following potential sweep from −1.10 to −0.50 V, reduced Cd was oxidized and a sensitive stripping peak appears at −0.77 V. The stripping peak current of Cd²⁺ changes linearly with concentration over the range 5.0 × 10⁻⁸ to 5.0 × 10⁻⁶ mol L⁻¹. The limit of detection was found to be 3.0 × 10⁻⁸ mol L⁻¹ for 2-min accumulation. Finally, this new sensing method was successfully used to detect Cd²⁺ in waste water samples.     

Experimental characterization of emulsion formation and coalescence by nuclear magnetic resonance restricted diffusion techniques

Nuclear magnetic resonance (NMR) is explored as a technique for noninvasively monitoring emulsion droplet formation and destabilization. The method makes use of the fact that the diffusion of oil molecules within oil-in-water emulsion droplets results in attenuation of a coherent magnetic signal that emanates from those molecules. If oil diffusion is limited by the size of the droplet, the shape of a plot of attenuation over time is directly affected by the droplet radius. We use this approach to determine noninvasively the effect of surfactant type, surfactant concentration, pH, and ionic strength on droplet sizes within a 40 wt% octane and water emulsion, stabilized by Tween 20 or β-lactoglobulin (β-Lg). We find that addition of the low-molecular-weight Tween 20 forms finer emulsion droplets than does addition of the protein, and that the Tween 20 emulsion is sensitive to surfactant concentration below a threshold “saturation” concentration. The droplet sizes in β-Lg-containing emulsions increase as pH increases above the isoelectric point and as ionic strength increases. The fact that the NMR technique does not mistake clusters of droplets for single large droplets makes the analysis of these effects unambiguous. We further extend the use of NMR diffusion techniques to monitor the effect of surfactant type, surfactant concentration, and convection on the rate of droplet coalescence. The ability of NMR methods to distinguish between large single droplets and droplet clusters makes it well-suited to monitor coalescence processes independently from flocculation.     

Characterizing cocoa butter seed crystals by the oil-in-water emulsion crystallization method

Unambiguous quantitative evidence for the catalytic action of seed crystals in cocoa butter is presented. We used an ultrasound velocity technique to determine the isothermal growth of solid fat content in cocoa butter oil-in-water emulsions, in which the probability of finding a seed crystal in any one droplet was around 0.37 at 14.2°C. The upper limit for the size of seed crystals in West African cocoa butter was around 0.09 μm, the Gibbs free energy for nucleation was 0.11 mj m⁻², and the concentration of seed crystals was in the range of 10¹⁶ to 10¹⁷ m⁻³. X-ray diffraction measurements showed that emulsified cocoa butter crystallizes in the α polymorph and does not appear to transform to the β′ form within the first 25 min of crystallization. Primary nucleation events in cocoa butter emulsions are accounted for by seed crystals. Collision-mediated nucleation, a secondary nucleation mechanism, in which solid droplets (containing seed crystals) catalyze nucleation in liquid droplets, is shown to account for subsequent crystallization. This secondary nucleation mechanism is enhanced by stirring.     

Protein binding study of catechin hydrate and genistein by high-performance frontal analysis

High-performance frontal analysis (HPFA) was used for the protein binding study of catechin hydrate and genistein to human serum albumin (HSA). The experiment was performed on a Develosil 100Diol-5 column, and sodium phosphate buffer (pH 7.4 and ionic strength of 0.17) was used as the mobile phase. The mixtures of the drug-HSA solution were directly injected into the HPFA column, the HSA was eluted first and the unbound drugs were eluted out as a trapezoidal peak with a plateau region. The unbound drug concentration was determined from a plateau height of the plateau region and the experimental data were fitted by Scatchard equation. The binding constants (K) and binding affinities (nK) of the drug to HAS were K=1.32×10⁴ (L mol⁻¹), nK=0.47×10⁴ (L mol⁻¹) for catechin hydrate, and K=5.17×10⁴ (L mol⁻¹), nK=2.14×10⁴ (L mol⁻¹) for genistein.     

Synthesis and characterization of aerogel-like mesoporous nickel oxide for electrochemical supercapacitors

Highly porous NiO was prepared via a combination of sol-gel process with supercritical drying method in this paper. The as-synthesized NiO samples exhibit 80–90% porosity and high surface area, ie, 180.5–325.6 m²g⁻¹. Cyclic voltammetric and chronopotentiometric measurements indicated the aerogel-like NiO in 1 mol.L⁻¹ KOH solution to behave capacitive well due to its uniform mesoporous microstructure. It was also observed that post-heating temperature plays a critical role in the mesoporous nature of the aerogel-like materials. An optimal heating temperature of 300^∘C was found to favor the formation of mesopores, which account for the large specific capacitance of as high as 125 F.g⁻¹. The average specific capacitance of the aerogel-like NiO was observed to be about 75–125 F.g⁻¹ between a potential window of 0–0.35 V vs. SCE.     

Nutrient flows in smallholder production systems in the humid forest zone of southern Cameroon

The flows and balances of N, P and K were studied in 20 farms in the Campo Ma’an area in Cameroon between March and August 2002 to assess the nutrient dynamics in smallholder farms. Data were collected through farmer interviews, field measurements and estimates from transfer functions. Nutrient input from mineral (IN1), animal feed (IN2a) and inorganic amendments (IN2b) was absent. Major outputs were through crop (OUT1a) and animal (OUT1b) products sold. Partial budgets for farmer managed flows were negative: −65 kg N, −5.5 kg P and −30.8 kg K ha⁻¹ year⁻¹. For inflows not managed by farmers, deep capture (IN6) was the major source: 16.6, 1.4 and 6.6 kg ha⁻¹ year⁻¹ of N, P and K, respectively. Atmospheric deposition (IN3) was estimated at 4.3 kg N, 1.0 kg P and 3.9 kg K ha⁻¹ year⁻¹, and biological nitrogen fixation (IN4) at 6.9 kg N ha⁻¹ year⁻¹. Major losses were leaching (OUT 3a): 26.4 kg N, and 0.88 kg K ha⁻¹ year⁻¹. Gaseous losses from the soil (OUT 4a) were estimated at 6.34 kg N, and human faeces (OUT 6) were estimated at 4 kg N, 0.64 kg P and 4.8 kg K ha⁻¹ year⁻¹. The highest losses were from burning (OUT 4c), i.e. 47.8 kg N, 1.8 kg P and 14.3 kg K ha⁻¹ year⁻¹. Partial budgets of environmentally controlled flows were negative only for N −4.8 kg N, +2.4 kg P and +9.6 kg K ha⁻¹ year⁻¹. The overall farm budgets were negative, with annual losses of 69 kg N, 3 kg P and 21 kg K ha⁻¹. Only cocoa had a positive nutrient balance: +9.3 kg N, +1.4 kg P and +7.6 kg K ha⁻¹ year⁻¹. Nutrients reaching the household waste (1.9 kg N, 2.8 kg P and 18.8 kg K ha⁻¹ year⁻¹), animal manure (4.9 kg N, 0.4 kg P and 1.6 kg K), and human faeces (4 kg N, 0.64 kg P and 4.8 kg K ha⁻¹ year⁻¹) were not recycled. Five alternative management scenarios were envisaged to improve the nutrient balances. Recycling animal manure, household waste and human faeces will bring the balance at −62.6 kg N, 0 kg P and +1 kg K ha⁻¹ year⁻¹. If, additionally, burning could be avoided, positive nutrient balances could be expected.     

Effects of fat crystallization on the behavior of proteins and lipids at oil droplet surfaces

The effects of fat crystallization induced by thermal treatment on the rheological properties of creams and physical phenomena at the oil droplet surfaces were investigated. Creams A or B were prepared from commercial proprietary fats A or B (vegetable oils with different triaclyglycerol composition) and aqueous solution containing proteins. Thermal treatment of the creams at the “critical temperatures” (temperatures inducing a small percentage of solid fats in the oil droplets) caused a rapid increase of solid fat contents in the following cooling process. The thermal treatment of cream B at the “critical temperature” caused an increase of viscosity of the cream and an increase of protein surface coverage during the subsequent cooling process. These results suggest that the oil droplet aggregation induced by the thermal treatment at the “critical temperature” and the subsequent cooling occurred via further adsorption of proteins. Electron spin resonance measurement demonstrated the dramatic reduction of fluidity of triacylglycerol molecules at the oil droplet surface in cream B during the cooling process after thermal treatment at temperatures below “critical”. Based on these results, we speculated on the mechanism for the destabilization of thermally treated creams during the cooling process.     

Removal of Pb(II) from simulated wastewaters using a stainless-steel wool cathode in a flow-through cell

The investigation of an electrolytic process to remove Pb(II) from simulated wastewaters using a stainless-steel wool (SSW) cathode in a flow-through cell under potentiostatic condition is reported. Voltammetry under hydrodynamic conditions was used to estimate the diffusion coefficient, which was found to be 1.4× 10⁻⁵ cm² s⁻¹ in the supporting electrolyte (0.10 mol l⁻¹ NaNO₃ and 0.10 mol l⁻¹ H₃BO₃, pH 4.8). The performance of the flow-through cell was evaluated for three potentials: −0.70, −0.80 and −0.90 V vs. saturated calomel electrode (SCE). At −0.70 V, the reaction was found not to be completely controlled by mass transfer, while at −0.80 V and −0.90 V the Pb(II) concentration decayed exponentially. At −0.90 V, using a flow rate of 250 l h⁻¹, after a 90-min electrolysis, the Pb(II) concentration decayed from 50 ppm to only 1 ppm, corresponding to a 98% removal.     

Liquid-phase polymer-based retention and coupled electrocatalytic oxidation to remove Arsenic in the presence of competitive species

The goal was to remove arsenate species in the presence of competitive anions by coupling of liquid-phase polymer-based retention, LPR, a procedure based on the selective As(V) adsorption properties of cationic water-soluble polymers, with an electro-catalytic oxidation process (EO) of As(III) into its more easily removable As(V). The electro-catalytic oxidation of As(III) to As(V) was performed with an organic supporting electrolyte, poly[3-(methacryloylamine)propyl)]trimethyl ammonium chloride, P(ClMPTA), which is recognized as an efficient reagent in removing divalent arsenate species. The bulk electro-catalytic conversion of As(III) to As(V) was carried out with a Pt-gauze electrode, and the resulting mixtures were introduced into a LPR cell to remove the As(V)-polymer adducts. Using P(ClMPTA) and ammonium salts at a 20:1 polymer:As(III) molar ratio at pH 8, complete (100%) Arsenic retention was achieved. For binary mixtures of Arsenic with competitive anions (e.g., SO₄ ²⁻, HPO₄ ²⁻, NO₃ ⁻, and NO₂ ⁻), the retention profile varied in the range 100–70%. In addition, the As(V) retention efficiency was found to be directly related to the consumed charge in the mol ratio As(III) in solution with competitive anionic species.     

Effects of ultrasonic irradiation on crystallization behavior of tripalmitoylglycerol and cocoa butter

Effects of application of ultrasonic power (20 kHz, 100 W) on the crystallization behavior of tripalmitoylglycerol (PPP) and cocoa butter have been examined in terms of rate of nucleation and polymorphic control. High-purity PPP (>99%) and low-purity PPP (>80%) samples were employed to mimic real fat systems, which usually have higher concentrations of minor components in addition to the main component. For both the high-purity and low-purity PPP, the application of ultrasonic power accelerated the rate of nucleation as measured by induction time for the occurrence of crystals and by the number of crystals nucleated. As for the polymorphic influences, the nucleation of both the β′ and β forms was accelerated by the ultrasound, yet the β′ form nucleation was more accelerated when the low-purity PPP samples were employed. As for cocoa butter, sonication for a short period accelerated the crystallization of Form V. The present results indicate that ultrasound irradiation is an efficient tool for controlling polymorphic crystallization of fats.     

Direct electrochemistry of chemically modified catalase immobilized on an oxidatively activated glassy carbon electrode

Catalase (Ct) was modified using Woodward’s reagent K (WRK) as a specific modifier of carboxyl residues. The modified Ct was immobilized on an oxidatively activated glassy carbon electrode surface to investigate its direct electrochemistry. Using cyclic voltammetry an irreversible reduction peak was obtained at approximately −0.362 V vs. Ag/AgCl in buffer solution, pH 7, and at a scan rate of 0.1 V s⁻¹. The electrochemical parameters, including charge-transfer coefficient (0.27), apparent heterogeneous electron transfer rate constant (13.51 ± 0.42 s⁻¹) and formal potential of the Ct film (−0.275 V) were determined. The prepared enzyme electrode exhibited a response to H₂O₂.     

Investigation of phase transitions in glyceride/paraffin oil mixtures using ultrasonic velocity measurements

A pulse echo technique has been used to measure the ultrasonic velocity of a number of 15% w/w glyceride/paraffin oil mixtures with increasing temperature (0–70 C). At the lower temperatures the glycerides are completely solid and there is a fairly steady decrease in velocity with temperature (ca. −3.8 ms⁻¹C⁻¹). As the temperature rises the glycerides become increasingly soluble in the paraffin oil and the velocity decreases more rapidly. Once the glyceride is completely soluble in the paraffin oil, a fairly steady decrease in velocity with temperature (ca. −3.3 ms⁻¹C⁻¹) resumes. The dependence of ultrasonic velocity on the amount of solid glyceride present means the technique can be used to investigate phase transitions in binary glyceride/oil mixtures.     

Phosphorus,Potassium and Leucaena Pruning Interactions on Corn in Haiti

Few P and K fertility studies have been conducted on Haitian soils. Alley cropping is promoted in Haiti but has not been studied in relation to P and K fertility. The effects of P and K fertilizer and leucaena (Leucaena leucocephala (Lam) De Witt) pruning mulch applications on corn (Zea mays L.) were assessed in field experiments on Rhodudalfs over limestone at Salagnac, Lithic Hapludolls over limestone at Bergeau and Typic Hapludalfs over basalt at St. Georges, Haiti. Complete block designs arranged in incomplete factorials of P and K rates were carried out during three seasons. Additional treatments consisted of 30 Mg ha⁻¹ of leucaena prunings applied with and without 60 kg P and 40 kg K ha⁻¹. Grain yield and net income were analyzed and a surface response curve was fitted on treatments without pruning applications. The soils differed markedly in response to P and K with significant PXK interactions. Without leucaena prunings, response surface analysis predicted maximum yields with applications of 95–117 kg P ha⁻¹ and 51–72 kg K ha⁻¹ and maximum net returns with applications of 0.22–89 kg P ha⁻¹ and 43–79 kg K ha⁻¹. Leucaena pruning applications increased yield at all sites. Highest net income was obtained at Salagnac and St. Georges with leucaena prunings applied with P and K, at Bergeau with prunings applied without P and K, suggesting that alley cropping with judicial fertilizer use is a good economic alternative for low resource farmers. Soil parent material and mineralogy should be considered in making fertilizer recommendations.