Non-thermal pasteurization of fruit juices by combining high-intensity pulsed electric fields with natural antimicrobials

The effect of high-intensity pulsed electric fields (HIPEF) on the Salmonella Enteritidis and Escherichia coli O157:H7 populations inoculated in apple, pear, orange and strawberry juices as influenced by treatment time and pulse frequency was investigated. Combinations of HIPEF (35 kV/cm, 4 μs pulse length in bipolar mode without exceeding 40 °C) with citric acid or cinnamon bark oil against these pathogenic microorganisms in fruit juices were also evaluated. Treatment time was the more influential factor on the microbial reduction in all the fruit juices analyzed. S. Enteritidis and E. coli O157:H7 were reduced by more than 5.0 log₁₀ units in orange juice treated by only HIPEF; whereas strawberry, apple and pear juices were pasteurized when HIPEF was combined with citric acid at 0.5, 1.5, 1.5%, respectively, or cinnamon bark oil at 0.05, 0.1 and 0.1%, respectively. Synergistic and additive killing effects against S. Enteritidis and E. coli O157:H7 in fruit juices by combining treatments were observed.

Industrial relevance

The use of high-intensity pulsed electric fields treatment as a non-thermal pasteurization method in combination with organic acids or essential oils is an effective process for eliminating S. Enteritidis and E. coli O157:H7 populations in fruit juices upper 5.0 log₁₀ reductions. Therefore, combinations of those treatments may help to ensure the microbiological safety in juice products, and to reduce the risk of food-borne illness caused by the consumption of these kinds of foods.     

Evaluation of standard and new chromogenic selective plating media for isolation and identification of Bacillus cereus

In this study, the performance of two new chromogenic plating media (CBC and BCM) was compared with two standard selective plating media (PEMBA and MYP) recommended by food authorities for isolation, identification and enumeration of Bacillus cereus. The four media types were challenged with a strain set comprising 100 B. cereus isolates from different origins and with different toxigenic potentials (40 food isolates, 40 isolates from food borne outbreaks and 20 clinical isolates). Additionally, the performance of the plating media for analysis of complex samples was assessed using naturally contaminated foods. Our survey showed that the new chromogenic media represent a good alternative to the conventional standard media. Especially, if laboratory staff are not highly trained in identification of B. cereus, the conventional media could lead to substantial misidentification and underestimation of food borne illness caused by B. cereus. However, there are some B. cereus strains that could not even be detected with this new type of chromogenic media. After the fatal misidentification of a highly toxic strain, other methods for a conclusive identification of B. cereus are needed. Sequence analysis of the plcR gene, a pleiotropic regulator of various virulence factors and B. cereus specific enzymes, revealed a significant correlation between atypical colony appearance and specific variances within the plcR gene sequences of those strains. The current concept of selective plating media, utilising PlcR regulated enzyme activities for differentiation purposes, should therefore be reconsidered and research should be geared towards culture independent methods.     

Large-scale phenotypic analysis reveals identical contributions to cell functions of known and unknown yeast genes.

Sequencing of the yeast genome has shown that about one-third of the yeast ORFs code for unknown proteins. Many other have similarity to known genes, but still the cellular functions of the gene products are unknown. The aim of the B1 Consortium of the EUROFAN project was to perform a qualitative phenotypic analysis on yeast strains deleted for functionally orphan genes. To this end we set up a simple approach to detect growth defects of a relatively large number of strains in the presence of osmolytes, ethanol, high temperature, inhibitory compounds or drugs affecting protein biosynthesis, phosphorylation level or nucleic acids biosynthesis. We have now developed this procedure to a semi-quantitative level, we have included new inhibitors, such as hygromycin B, benomyl, metals and additional drugs interfering with synthesis of nucleic acids, and we have performed phenotypic analysis on the deleted strains of 564 genes poorly characterized in respect to their cellular functions. About 30% of the deleted strains showed at least one phenotype: many of them were pleiotropic. For many gene deletions, the linkage between the deletion marker and the observed phenotype(s) was studied by tetrad analysis and their co-segregation was demonstrated. Co-segregation was found in about two-thirds of the analysed strains showing phenotype(s).     

Summoning earth and fire: The energy development implications of Grameen Shakti (GS) in Bangladesh

Since its establishment in 1996, the nonprofit company Grameen Shakti (GS) has installed almost half a million solar home systems (SHS), 132,000 cookstoves, and 13,300 biogas plants among 3.1 million beneficiaries. They plan to ramp up their expansion so that by 2015, more than 1.5 million SHS are in place along with 100,000 biogas units and 5 million improved cookstoves. This article describes GS’s current activities, the contours of its programs, and likely reasons for its success. It also explores the remaining challenges facing GS and distils common lessons for other energy development assistance projects and programs around the world. After detailing research methods consisting primarily of research interviews and site visits, the article briefly explores the history of GS and summarizes its three most prominent programs. The article then identifies six distinct benefits to their programs—expansion of energy access, less deforestation and fewer greenhouse gas emissions, price savings, direct employment and income generation, improved public health, and better technology—before discussing challenges related to staff retention and organizational growth, living standards, technical obstacles, affordability, tension with other energy programs, political constraints, and awareness and cultural values.     

Optimisation of the Mashing Procedure for 100% Malted Proso Millet (Panicum miliaceum L.) as a Raw Material for Gluten‐free Beverages and Beers

Proso millet is a gluten‐free cereal and is therefore considered a suitable raw material for the manufacturing of foods and beverages for people suffering from celiac disease. The objective of this study was to develop an optimal mashing procedure for 100% proso millet malt with a specific emphasis on high amylolytic activity. Therefore, the influence of temperature and pH on the amylolytic enzyme activity during mashing was investigated. Size exclusion chromatography was used to extract different amylolytic enzyme fractions from proso millet malt. These enzymes were added into a pH‐adjusted, cold water extract of proso millet malt and an isothermal mashing procedure was applied. The temperatures and pH optima for amylolytic enzyme activities were determined. The α‐amylase enzyme showed highest activity at a temperature of 60°C and at pH 5.0, whereas the β‐amylase activity was optimum at 40°C and pH 5.3. The limit dextrinase enzyme reached maximum activity at 50°C and pH 5.3. In the subsequent mashing regimen, the mash was separated and 40% was held for 10 min at 68°C to achieve gelatinisation. The next step in the mashing procedure was the mixture of the part mashes. The combined mash was then subjected to an infusion mashing regimen, taking the temperature optima of the various amylolytic enzymes into account. It was possible to obtain full saccharification of the wort with this mashing regimen. The analytical data obtained with the optimised proso millet mash were comparable to barley wort, which served as a control.     

Multilevel converters for single-phase grid connected photovoltaic systems: an overview

Multilevel voltage source inverters offer several advantages compared to their conventional counterparts. By synthesising the AC output terminal voltage from several levels of DC voltages, staircase waveforms can be produced, which approach the sinusoidal waveform with low harmonic distortion, thus reducing filter requirements. The need of several sources on the DC side of the converter makes multilevel technology attractive for photovoltaic applications. This paper provides an overview on different multilevel topologies and investigates their suitability for single-phase grid connected photovoltaic systems. Several transformerless photovoltaic systems incorporating multilevel converters are compared regarding issues such as component count and stress, system power rating and the influence of the photovoltaic array earth capacitance.     

Lithium bis(fluorosulfonyl)imide-PYR14TFSI ionic liquid electrolyte compatible with graphite

Lithium bis(fluorosulfonyl)imide (LiFSI) in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR₁₄TFSI) was successfully tested as an electrolyte for graphite composite anodes at elevated temperature of 55 °C. The graphite anode showed a good cyclability during the galvanostatic testing at C/10 rate and 55 °C with the capacity close to theoretical. The formation of SEI in different electrolytes was the subject of study using impedance spectroscopy on symmetrical cells containing two lithium electrodes. The 0.7 m LiFSI in PYR₁₄TFSI exhibits a good ionic conductivity (5.9 mS cm⁻¹ at 55 °C) along with high electrochemical stability and high thermal stability. These properties allow their potential application in large-scale lithium ion batteries with improved safety.     

Evaluating energy security performance from 1990 to 2010 for eighteen countries

This study provides an index for evaluating national energy security policies and performance among the United States, European Union, Australia, New Zealand, China, India, Japan, South Korea, and the ten countries comprising the Association of Southeast Asian Nations (ASEAN). Drawn from research interviews, a survey instrument, and a focused workshop, the article first argues that energy security ought to be comprised of five dimensions related to availability, affordability, technology development, sustainability, and regulation. The article then breaks these dimensions down into 20 components and correlates them with 20 metrics that constitute a comprehensive energy security index. We find that the top three performers of our index for all data points and times are Japan, Brunei, and the United States and the worst performers Vietnam, India, and Myanmar. Malaysia, Australia, and Brunei saw their energy security improve the most from 1990 to 2010 whereas Laos, Cambodia, and Myanmar saw it decline the most. The article concludes by calling for more research on various aspects of our index and its results.     

Study on the applicability of high-pressure homogenization for the production of banana juices

The aim of this preliminary study was to evaluate the potential applicability of high-pressure homogenization (HPH) for the production of banana juices. To this purpose, a prototype equipment working up to 400 MPa and a lab-scale homogenizer working up to 150 MPa were used. Temperature, microbial load, pectate lyase activity, colour and viscosity of the samples homogenized at increasing pressure were evaluated. Pressures higher than 200 MPa were needed to obtain 4 log unit reduction of total mesophilic bacteria and pectate lyase inactivation. Following HPH, banana juice resulted brighter and less viscous than the untreated one. Data suggest that HPH treatments could be a reliable technological alternative to conventional heat treatments for the production of added-value fruit juices. However, the homogenization design could play a critical role in affecting the product quality attributes. In fact, homogenization performed at the same operative pressure by using different equipment leads to different effects on product quality.