Optimization of molecular distillation to concentrate ethyl esters of eicosapentaenoic (20:5 ω-3) and docosahexaenoic acids (22:6 ω-3) using simplified phenomenological modeling

BACKGROUND: Squid oil contains high concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The purpose of this work was to optimize the process of separation by molecular distillation of ω‐3 fatty acid ethyl esters obtained from squid oil. The separation process was conducted in two stages in a laboratory‐scale molecular distiller. A mathematical model based on the mass transfer phenomena was developed. The Nelder‐Mead numerical method was used to optimize the model. RESULTS: The ω‐3 content in the output material of the stage II increased with the temperature of stage I (T¹). The amount of distillated material in stage I increased and the distillated material in the stage II decreased with the increment of T¹. That implied a decreasing of the ω‐3 recovery in the distillated material in the stage II. In addition, the ω‐3 recovery increased with the temperature of stage II (T²), but the temperatures should be less than 140 °C to avoid chemical changes. The optimization results showed an optimal process at T¹ = 120.5 °C and T² = 140 °C. CONCLUSION: The theoretical model and the optimization give decision criteria about the operative conditions for reaching the highest yield during molecular distillation of ω‐3 fatty acid ethyl esters. Copyright © 2011 Society of Chemical Industry     

Protein content of grains of different size fractions in malting barley

The negative relationship between grain size (percentage >2.5 mm) and protein content usually observed in barley grain samples is attributed to the presence of thin grains. The objective of this study was to determine whether, in grain samples from a given environment, thin grains had a different protein content than plump grains. Grain samples from field experiments were analysed for grain yield, size and protein content of the whole sample and of four size fractions within each sample. Grain yield ranged from 1.5 to 6.5 mg ha^?1 and grain protein (whole sample) ranged from 6.8 to 13.4 %. Most of the variation observed in protein content was explained by the ratio of nitrogen availability to grain yield. Within a grain sample, thin grains had more protein than plump grains (>2.5 mm) only when the protein content of the whole sample was high, that is, when the grain sample came from an environment with a high relative abundance of nitrogen. The fact that grain samples with low grain size tend to have high protein content is not due to the presence of a high proportion of thin grains, because thin grains do not always have more protein than plump grains. Copyright © 2014 The Institute of Brewing & Distilling     

Development of a PCR-culture technique for rapid detection of yeast species in vacuum packed ham

A rapid assay for detection of yeast species in vacuum packed ham has been developed based on the polymerase chain reaction (PCR) coupled to a 24 h pre-enrichment at 25 °C. DNA was isolated from yeast inoculated ham samples and amplified using primers specific for the 18S rRNA gene sequences of yeasts. A detection limit of 10(2) CFU/cm(2) was achieved following enrichment of samples experimentally inoculated with three yeast species frequently associated with meat products spoilage: Debaryomyces hansenii, Yarrowia lipolytica, and Kluyveromyces marxianus. Likewise, commercial sliced and vacuum packed ham samples were analysed using the PCR-culture technique. The results obtained in this work show that PCR amplification of a conserved region of the 18S rRNA gene in the yeast species could be potentially used as a rapid tool for detection of low levels of viable spoilage yeasts in meat products.     

Influence of nitrogen on the biological aging of sherry wine

Nitrogen compounds are essential to the growth and metabolism of yeasts. The uptake and metabolism of nitrogen compounds by Saccharomyces cerevisiae depend not only on the strain and its physiological condition, but also on the chemical and physical properties of its environment. The effect of the addition of different amino acids (L ‐proline, L ‐threonine, L ‐arginine, L ‐glutamic acid, L ‐leucine and L ‐valine) to nitrogen‐depleted natural or nitrogen‐free synthetic wine on the cell growth, flor velum formation and sherry wine compound production was investigated under controlled biological aging by S. cerevisiae var. capensis strain G1 a typical flor yeast. The formation of flor velum was dependent on particular amino acid, oxygen availability and the composition of wine. Consumption of glycerol was related with the cell growth; in contrast, acetaldehyde tended to be released. Amino acid supplementation resulted in the release to wine of amino acids, esters and higher alcohols. The amino acid which was released in nearly all cases was L ‐leucine. Addition of L ‐glutamic acid resulted in the release mainly of ethyl acetate, in the case of L ‐leucine isoamyl alcohols were released, and for L ‐valine isobutanol. In the three cases, 1,1‐diethoxyethane was released in large quantities. The findings might indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential. Copyright © 2006 Society of Chemical Industry     

Differentiation and characterization by molecular techniques of Bacillus cereus group isolates from poto poto and dégué, two traditional cereal-based fermented foods of Burkina Faso and Republic of Congo

Poto poto (a maize sourdough) and dégué (a pearl millet-based food) are two traditional African fermented foods. The molecular biology of toxigenic and pathogenic bacteria found in those foods is largely unknown. The purpose of this study was to study the phylogenetic relatedness and toxigenic potential of 26 Bacillus cereus group isolates from these traditional fermented foods. The relatedness of the isolates was evaluated with repetitive element sequence-based PCR (REP-PCR) and 16S rDNA sequencing analysis. A multiplex real-time PCR assay targeting the lef and capC genes of B. anthracis pXO1 and pXO2 plasmids and the sspE chromosomal gene of B. cereus and B. anthracis also was carried out. Melting curve analysis of the sspE amplification product was used to differentiate B. cereus from B. anthracis, and the presence of the B. cereus enterotoxin genes was determined with PCR amplification. Isolates had 15 different REP-PCR profiles, according to which they could be clustered into four groups. 16S rDNA sequencing analysis identified 23 isolates as B. cereus or B. anthracis and three isolates as B. cereus or Bacillus sp. Multiplex real-time PCR amplification indicated the absence of the lef and capC genes of B. anthracis pXO 1 and pXO2 plasmids, and melting curve analysis revealed amplification of the 71-bp sspE product typical of B. cereus in all isolates instead of the 188-bp amplicon of B. anthracis, confirming the identity of these isolates as B. cereus. Four isolates had amylolytic activity. All isolates had lecithinase activity and beta-hemolytic activity. Enterotoxin production was detected in two isolates. The emetic toxin gene was not detected in any isolate. The nheB toxin gene was detected in 19 isolates by PCR amplification; one of these isolates also contained the hblD (L1) gene. The cytotoxin K cytK-1 gene was not detected, but the cytK-2 gene was clearly detected in six isolates.     

Effect of phytate and storage conditions on the development of the ‘hard‐to‐cook’ phenomenon in common beans

Postharvest storage of beans (Phaseolus vulgaris L.) can alter the color, texture, flavor and time required for cooking. These alterations have been associated with the ‘hard‐to‐cook’ phenomenon (HTC) and a reduction in the quality of the grains. HTC has been linked to the genotype, environment and/or storage conditions of the grains, but very few studies have shown the interrelationship between these factors. Therefore, the objective of this study was to analyze the effect of two genotypes, Paraiso and Peruano, grown under the same phosphorus levels, on the development of HTC. These genotypes were evaluated for phytate, protein, tannin and phosphorus contents, hydration time and cooking time when stored for 45, 90 and 135 days, at 29 °C and 5 °C at a relative humidity of 75%. HTC was observed in Peruano after 135 days, which correlated with a reduction in the phytate content. Paraiso did not show HTC even though there was a reduction of tannins during the storage period. The lower storage temperature appeared to control HTC for both genotypes. Overall, the content of phytate can be an indicative factor for the cookability of fresh beans when the relationship between genotype and storage conditions has been determined. Copyright © 2007 Society of Chemical Industry     

Numerical simulations of rear point‐contacted solar cells on 2.2 Ωcm p‐type c‐Si substrates

Rear surface of high‐efficiency crystalline silicon solar cells is based on a combination of dielectric passivation and point‐like contacts. In this work, we develop a 3D model for these devices based on 2.2 Ωcm p‐type crystalline silicon substrates. We validate the model by comparison with experimental results allowing us to determine an optimum design for the rear pattern. Additionally, the 3D model results are compared with the ones deduced from a simpler and widely used 1D model. Although the maximum efficiency predicted by both models is approximately the same, large deviations are observed in open‐circuit voltage and fill factor. 1D simulations overestimate open‐circuit voltage because Dember and electrochemical potential drops are not taken into account. On the contrary, fill factor is underestimated because of higher ohmic losses along the base when 1D analytical model is used. These deviations are larger for relatively low‐doped substrates, as the ones used in the experimental samples reported hereby, and poor passivated contacts. As a result, 1D models could mislead to too short optimum rear contact spacing. Copyright © 2013 John Wiley & Sons, Ltd.     

A Case Study of GAMM (Graphical Analysis for Maintenance Management) Applied to Water Pumps in a Sewage Treatment Plant,Chile

This article presents a case for practical application of the GAMM method, which has been developed and published by the authors. The GAMM method supports decision making in the overall maintenance management, through the visualization and graphical analysis of data. In addition, it allows for the identification of anomalous behavior in the equipment analyzed, whether derived from its own operations, maintenance activities, improper use of equipment or even as a result of design errors in the equipment itself. As a basis for analysis, the GAMM method uses a nonparametric estimator of the reliability function using all historical data or, alternatively, part of the history, allowing it to perform an analysis even with limited available data. In the case study presented, the GAMM method has been used to analyze two existing equipment parts in a sewage treatment plant located in Chile. The equipment analyzed were two progressive cavity pumps (BCP) which are part of the industrial process in the treatment plant. Both pumps are the same make and model and subjected to the same maintenance program, but one had a higher failure rate compared to its counterpart. The application of the GAMM method has identified deficiencies in each of the pumps being studied, thus improving decision‐making and problem‐solving process related to the maintenance of the pumps. RCM methodology was used to draft a new maintenance plan. Copyright © 2013 John Wiley & Sons, Ltd.     

Reconciling the ETSI coverage requirements for DVB-T with the ITU-R recommendations

Digital Video Broadcasting Terrestrial (DVB-T) is a standard issued by the European Telecommunications Standards Institute (ETSI). The ETSI also issued some implementation guidelines regarding transmission aspects which include coverage requirements. For broadcasting designers, the main reference for calculating coverage is the recommendations of the International Telecommunication Union—Radiocommunication Sector (ITU-R). However, we are in trouble if we try to use the ITU-R recommendations to meet the ETSI coverage requirements because the latter specify a minimum signal level at the receiver to be guaranteed over 99 % of time whereas the ITU-R recommendations only give a calculation procedure for up to 50 % of the time. The present paper offers a method in order to adapt the ETSI coverage requirements to the ITU-R recommendations, based on a research measurement of the DVB-T signal level received in four different environments over a long period of time.