Use of electronic nose,validated by GC–MS,to establish the optimum off-vine dehydration time of wine grapes

Pedro Ximénez grapes were sun dried for 0, 2, 4, 6 and 9 days and the resulting must was analysed by gas chromatography and by an electronic nose. In the last stages of the process compounds related with ripe fruity and toasty aromas decreased whereas the concentration of sugars increases slightly, which suggests that the optimum dehydration time is reached before the ninth day. A discriminant analysis of data by the electronic nose allows for the differentiation of the must from dried grapes. Multiple regression analysis was made with the aim of relating the aroma that best described the must from dried grapes with the data reported by the electronic nose, obtaining a correlation above 99%. Therefore, according to the obtained results the electronic nose can be used as a tool for quick analysis that can help winemakers to decide the optimum drying time, taking into account the concentration of volatile compounds.     

Lactulose as a food ingredient

Lactulose is a synthetic ketose disaccharide that can be obtained from lactose by different methods of synthesis. Chemical methods are based on the isomerization of lactose in the presence of basic catalysts and enzymatic methods using lactose as a galactose donor and fructose as an acceptor. The prebiotic properties of lactulose have been known for more than 50 years and numerous studies have confirmed several health benefits of lactulose as a food ingredient, including selective stimulation of intestinal flora, laxative effect and improvement of calcium absorption. Its use in fermented milk manufacture may reduce the incubation period and favour the growth of bifidobacteria. The synthesis of lactulose‐derived oligosaccharides may provide a new group of prebiotics with properties complementary to those of native lactulose. Copyright © 2009 Society of Chemical Industry     

Wine yeast molecular typing using a simplified method for simultaneously extracting mtDNA,nuclear DNA and virus dsRNA

Quick and accurate methods are required for the identification of industrial, environmental, and clinical yeast strains. We propose a rapid method for the simultaneous extraction of yeast mtDNA, nuclear DNA, and virus dsRNA. It is simpler, cheaper, and faster than the previously reported methods. It allows one to choose among a broad range of molecular analysis approaches for yeast typing, avoiding the need to use of several different methods for the separate extraction of each nucleic acid type. The application of this method followed by the combined analysis of mtDNA and dsRNA (ScV-M and W) is a highly attractive option for fast and efficient wine yeast typing.     

Modelling of the rehydration process of brocolli florets

The aim was to study the rehydration kinetics of branched bodies such as broccoli florets, at different temperatures, and to this end a diffusional model was used considering the product structure as a sum of different sized cylinders. The rehydration rate was observed to increase with water temperature. The equilibrium moisture content of the product linearly decreased as the water temperature increased (r=0.95). A close fit between the model and the experimental data was obtained when the effective diffusion coefficient (D_eff) and equilibrium moisture content (W_e) were identified at each temperature (average explained %var=99.65). The temperature influence on D_eff was interpreted by the Arrhenius relationship, with an activation energy of 89.73 kJ/mol.     

Dealing with explicit preferences and uncertainty in answer set programming

In this paper, we show how the formalism of Logic Programs with Ordered Disjunction (LPODs) and Possibilistic Answer Set Programming (PASP) can be merged into the single framework of Logic Programs with Possibilistic Ordered Disjunction (LPPODs). The LPPODs framework embeds in a unified way several aspects of common-sense reasoning, nonmonotonocity, preferences, and uncertainty, where each part is underpinned by a well established formalism. On one hand, from LPODs it inherits the distinctive feature of expressing context-dependent qualitative preferences among different alternatives (modeled as the atoms of a logic program). On the other hand, PASP allows for qualitative certainty statements about the rules themselves (modeled as necessity values according to possibilistic logic) to be captured. In this way, the LPPODs framework supports a reasoning which is nonmonotonic, preference- and uncertainty-aware. The LPPODs syntax allows for the specification of (1) preferences among the exceptions to default rules, and (2)?necessity values about the certainty of program rules. As a result, preferences and uncertainty can be used to select the preferred uncertain default rules of an LPPOD and, consequently, to order its possibilistic answer sets. Furthermore, we describe the implementation of an ASP-based solver able to compute the LPPODs semantics.     

Computational aids for the estimation of the molecular weight of petroleum oils from kinematic viscosity measurements

The ASTM standard D 2502-92 (reapproved 2004) provides a means of calculating the mean molecular weight (relative molecular mass) of petroleum oils from kinematic viscosity measurements. It is applicable to samples with molecular weights in the range from 250 to 700 g/mol and is intended for use with average petroleum fractions. Nevertheless, this estimation was carried out by using a viscosity-molecular weight chart that involves evident interpolation errors. In this work, we have used both of Hirschler’s equations as numerical methods in order to carry out an analytical estimation of the mean molecular weight of petroleum oils from kinematic viscosity measurements. The data provided by the named Hirschler-Maroto equation are in excellent agreement with the ASTM chart for a viscosity index range that covers the majority of commercial oils. Finally, by using the Hirschler-Maroto equation we have designed a PC program in order to make the evaluation of molecular weight of petroleum oils easier for engineers and professionals. The use of this program, which can be downloaded free from the Internet, only requires the insertion of kinematic viscosity data, which remove any graphical or interpolation errors. Nevertheless, the Hirschler-Maroto equation and the PC program must be cautiously used in order to avoid important errors when applied to the higher molecular weight constituents of petroleum. Published in Russian in Neftekhimiya, 2007, Vol. 47, No. 2, pp. 103–107. The text was submitted by the authors in English.