A review of volatile analytical methods for determining the botanical origin of honey

Aroma is an important quality factor in foods. The aroma of bee honey depends on volatile fraction composition, which is influenced by nectar composition and floral origin. Honey of unifloral origin usually commands higher commercial value, thus the floral determination and certification of unifloral honey plays an important role in quality control. This review concerns investigations made on the volatile fraction of bee honey by gas chromatography/mass spectrometry. Recent advances in extraction methods, results achieved, and comparisons of alternative dependable methods for determining floral origin of bee honey are discussed. We emphasize solid phase micro-extraction gas chromatography (SPME/GC) methodology and present some of the results obtained to date, plus the advantages and drawbacks of SPME/GS in comparison with other methods.     

Multidimensional knapsack problem: a fitness landscape analysis.

Fitness landscape analysis techniques are used to better understand the influence of genetic representations and associated variation operators when solving a combinatorial optimization problem. Five representations are investigated for the multidimensional knapsack problem. Common mutation operators, such as bit-flip mutation, are employed to generate fitness landscapes. Measures such as fitness distance correlation and autocorrelation are applied to examine the landscapes associated with the tested genetic encodings. Furthermore, additional experiments are made to observe the effects of adding heuristics and local optimization to the representations. Encodings with a strong heuristic bias are more efficient, and the addition of local optimization techniques further enhances their performance.     

Hydrodynamics of a superheated steam vacuum fluidized bed

Hydrodynamics of a superheated steam vacuum fluidized bed was experimentally studied. In these experiments, eight different types of large particles (1970–7430 μm) were used. In all cases, a behavior similar to that found in an air fluidized bed was observed. The minimum fluidization velocity was found to be increasing with decreasing operating pressure. In the case of employing superheated steam, the minimum fluidization conditions are established at a lower velocity than using air as the fluidizing medium. These tendencies are attributed to the variation of the mean free path of molecules. On the other hand, the experiments showed that the bed voidage in the minimum fluidization conditions is almost insensitive to the variation of the operating pressure. Several equations were developed to predict the minimum fluidization velocity. The values provided by these equations were compared with the experimental data as well as with the predictions of the correlations presented in the technical literature.     

Synthesis and Characterization of Ultra-Fine Tin Oxide Fibers Using Electrospinning

Ultrafine tin oxide (SnO₂) fibers having a rutile structure, with diameter ranging from 100 nm to several micrometers, were synthesized using electrospinning and metallorganic decomposition techniques. In this work, we propose a precursor solution that is a mixture of pure SnO₂ sol made from SnCl₄:H₂O:C₃H₇OH:2-C₃H₇OH at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) (molecular weight 900 000) and chloroform (CHCl₃) at a ratio of 200 mg PEO/10 mL CHCl₃. This solution allows to obtain an appropriate viscosity for the electrospinning process. The as-deposited fibers were sintered at 400°, 500°, 600°, 700°, and 800°C in air for 2 h. Scanning electron microscopy, scanning probe microscopy, X-ray diffraction, Raman microspectrometry, and X-ray photoelectron spectroscopy (XPS) were used to characterize the sintered fibers and elucidate the chemical reaction during sintering. The results showed that up to the sintering temperature of 700°C, the synthesized fibers are composed of SnO₂. XPS was found to reflect the complicate chemical changes caused by the sintering process.     

Electrochemical treatment of diluted cyanide aqueous wastes

The electrochemical oxidation of diluted cyanide aqueous wastes has been studied in a single compartment electrochemical flow cell. It has been determined that the anode material influences greatly the process's performance. Boron doped diamond and PbO₂ anodes can oxidize these wastes in the presence of both sulfate or chloride anions. On the contrary, dimensional stable anodes cannot oxidize cyanide in sulfate‐containing wastewaters, and require the presence of chloride ions. The oxidation of cyanides leads to the formation of cyanate in a first step, and later to the formation of carbon dioxide and nitrogen. There is a net consumption of hydroxyl ions during the process. Energy consumptions in the range 20–70 kWh m^?3 are required to decrease the initial pollutant load by 70–80%. Global current efficiencies in the range 3–8% are obtained. These low current efficiencies are justified by the low cyanide concentrations that the wastes used in this work contain. Copyright © 2005 Society of Chemical Industry     

Odour‐active compounds in pineapple (Ananas comosus [L.] Merril cv. Red Spanish)

Application of solid‐phase microextraction, simultaneous distillation–extraction and liquid–liquid extraction combined with GC‐FID, GC‐MS, aroma extract dilution analysis, and odour activity value was used to analyse volatile compounds from pineapple (Ananas comosus [L.] Merril cv. Red Spanish) and to estimate the most odour‐active compounds. The analyses led to the identification of ninety‐four compounds, seventy‐two of them were positively identified. Twenty odorants were considered as odour‐active compounds, from which ethyl 2‐methylbutanoate, 2,5‐dimethyl‐4‐hydroxy‐3(2H)‐furanone, 1‐(E,Z,Z)‐3,5,8‐undecatetraene, ethyl 3‐(methylthio)propanoate, 1‐(E,Z)‐3,5‐undecatriene, ethyl hexanoate and methyl hexanoate were the most odour contributors and contribute to the typical pineapple aroma, while the others are responsible for fruity and sweet odour notes.     

Identification of multibody vehicle models for crash analysis using an optimization methodology

This work proposes an optimization methodology for the identification of realistic multibody vehicle models, based on the plastic hinge approach, for crash analysis. The identification of the design variables and the objective function and constraints are of extreme importance for the success of the optimization. The characteristics of the plastic hinges are used as design variables while the objective functions are formulated with measures of the difference between the dynamic response of the model and a reference response. The sequential application of genetic and gradient-based optimization methods is used to solve the optimization problem constituting a systematic approach to the automatic identification of vehicle multibody models. The methodology is demonstrated with the identification of the multibody model of a large family car for side and front crash. The vehicle model is developed in the MADYMO multibody code which is linked with the optimization algorithms implemented in the Matlab Optimization Toolbox.     

Comparisons of coherent systems using stochastic precedence

The comparisons of coherent systems is a relevant topic in reliability and survival studies. To this purpose, several techniques have been proposed including comparisons of expected lifetimes or comparisons using stochastic orderings. Recently, Samaniego (System Signatures and Their Applications in Engineering Reliability. International Series in Operations Research & Management Science, vol. 110. Springer, New York, 2007) proposed using stochastic precedence to compare the lifetimes of two independent coherent systems. He proved that if the components in both systems are independent and identically distributed (IID), then these comparisons are distribution free, while comparisons based on expected values are not. In the present paper, we obtain new expressions to compare systems using stochastic precedence without the assumption of IID components. In particular, we show that if the components in both systems are independent and satisfy the Cox proportional hazard rate (PHR) model with the same baseline hazard rate, then these comparisons do not depend on the baseline hazard rate function.     

Rheology of Cream-like Emulsions Prepared with Soybean Milk and Low Trans Vegetable Fat

The objective of this work was to study the effect of fat globule size and fat content on the rheological behavior of oil-in-water emulsions prepared with soybean milk, sunflower oil and low trans vegetable fat (LTF). Emulsions were prepared with 40 % w/w lipid phase (containing different proportions of LTF) and three different homogenization methods were used in order to obtain different globule sizes. Emulsions were subjected to controlled magnetic shaking until an increase in thickness. Partial coalescence was observed in all systems containing solid fat, which gave a rheopectic behavior and an increase in the viscoelastic parameters of the emulsions. Smaller particle sizes required higher shaking times to produce an increase in thickness, even though this did not lead to different final values of the viscoelastic parameters. The highest partial coalescence degree was observed at 50 % LTF in lipid phase, but the highest final viscoelastic parameters after shaking were observed at 100 % LTF in the lipid phase. The rheological behavior of these emulsions indicates that they could be a potential vegetable substitute for traditional dairy creams.