Effects of Quillaja saponaria extract and Nα-lauroyl-l-arginine ethyl ester on reducing selected foodborne pathogens in vitro and maintaining quality of fresh-cut endive (Cichorium endivia L.) at pilot plant scale

The aim of the present study was to evaluate the applicability of Quillaja saponaria extract (QSE) and N^α-lauroyl-l-arginine ethyl ester (LAE) as antimicrobial wash water additives in fresh-cut lettuce processing. Antibacterial activities of LAE and QSE against selected strains of the foodborne pathogens Salmonella enterica, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Listeria monocytogenes were examined in vitro. Minimum inhibitory concentrations determined by broth microdilution assay demonstrated that LAE exhibited a strong antimicrobial activity with MICs between 4 and 32 μg/mL against all tested strains, whereas QSE showed a weaker antimicrobial activity with MICs >512 μg/mL. On a pilot-plant scale, the effects of warm water washing at 45 °C for 120 s with and without 40 mg/L QSE or 100 mg/L LAE as well as cold water washing at 4 °C for 120 s with QSE or LAE, respectively, of shredded endive (Cichorium endivia L.) were investigated regarding microbiological and sensory quality as well as physiological properties. Samples were analyzed for headspace O₂ and CO₂ levels, phenylalanine-ammonia-lyase activity and contents of nitrite and nitrate during nine days of cold storage at 4 °C. By analogy to its antimicrobial effect against the foodborne pathogens in vitro, LAE allowed up to 4 log₁₀ cfu/mL reduction of the microbial load in the washing water of the pilot plant, and might therefore reduce cross-contamination while saving water. The addition of LAE to warm washing water impaired sensory properties of fresh-cut endive during storage, which was predicted by chlorophyll fluorescence imaging analyses. QSE treatment combined with warm water washing best retained sensory appearance throughout our study, being possibly suitable for the production of premium products.     

A novel developed method based on single primer isothermal amplification for rapid detection of Alicyclobacillus acidoterrestris in apple juice

Alicyclobacillus acidoterrestris (A. acidoterrestris), as one of the most major spoilage-causing species within the Alicyclobacillus genus, can survive and multiply in the pasteurization process. Nowadays, A. acidoterrestris has become worldwide issue in the fruit juice industry due to its spore-forming and thermo-acidophilic features. A novel single primer isothermal amplification assay (SPIA) was developed for the rapid detection of A. acidoterrestris in apple juice. This assay was designed to target the 16S rRNA gene with a DNA/RNA chimeric primer. Detection of gene amplification was accomplished by amplification curve, turbidity and addition of single strand DNA binding dye SYBR Green II allowing visualization under ultra violet light. The specificity of the assay was confirmed using 7 strains of A. acidoterrestris and 30 strains of non-A. acidoterrestris. The SPIA was highly sensitive and the detection limit was as low as 4.8 CFU/mL. Furthermore, the apple juice inoculated with 61 CFU/mL of A. acidoterrestris could be detected as positive. The novel SPIA with visualization results was successfully applied for the detection of A. acidoterrestris and exhibited high specificity and sensitivity, making it a powerful tool for the detection of A. acidoterrestris in fruit juice industry and being conveniently applied in developing countries with limited resource.     

Growth of Escherichia coli,Salmonella enterica and Listeria spp., and their inactivation using ultraviolet energy and electrolyzed water,on ‘Rocha’ fresh-cut pears

The present study aimed at evaluating the growth of Escherichia coli, Salmonella enterica, and Listeria spp. and studying the efficacy of Ultraviolet-C (UV-C) irradiation, acidic electrolyzed (AEW) and neutral electrolyzed (NEW) waters in the reduction of these bacteria on ‘Rocha’ pear. Fresh-cut pieces were inoculated and incubated at 4–20 °C for 8 days. Inoculated pears were treated with UV-C (2.5–10 kJ/m²), AEW, NEW and sodium hypochlorite (SH) and microbiological and quality parameters were evaluated. The three bacteria, inoculated at 6.1–6.2 log cfu/g, grew on the pear at high growth rates at 12 and 20 °C reaching populations of 8.1–8.6 log cfu/g, in 24 h. At 8 °C the microorganisms increased their populations by at least 1 log cfu/g in three days. At 4 °C adaptation phases of less than 24 h for Listeria spp. were measured before exponential growth occurred and the enterobacteria did not grow despite having survived for 8 days. AEW and NEW caused microbial reductions similar to SH, of approximately 1 log cfu/g, while the best UV-C dose (7.5 kJ/m²) of at least 2.4 log cfu/g. Fresh-cut pears were a good substrate for foodborne bacteria emphasizing the importance of preventing contaminations and cross contaminations. The UV-C was more effective than the chemical decontaminations, as it provided superior microbial reductions without greatly affecting the quality of pears.     

Esterase activity inspired selection and characterization of zearalenone degrading bacteria Bacillus pumilus ES-21

Zearalenone (ZEN), mainly produced by Fusarium species, is an estrogenic mycotoxin which causes reproductive disorders in livestock. In this study, we described a simple and rapid method for screening of ZEN-degrading bacteria by esterase activity assay. Soil bacteria strains were first tested for their esterase activities, then active strains were further evaluated for their ZEN-degrading potentials. A bacterial strain named Bacillus pumilus ES-21 was detected to be able to eliminate ZEN in the culture medium. ZEN degradation conditions were optimized through response surface methodology and the result showed that the degradation rate of ZEN by Bacillus pumilus ES-21 was up to 95.7% at the ZEN concentration of 17.9 μg/ml within 24 h. One of the degradation product was proposed to be 1-(3,5-dihydroxyphenyl)-6′-hydroxy-l′-undecen-l0′-one according to LC-TOF-MS/MS analysis. This study provided a strategy for the isolation of ZEN degrading microbes and a promising degrading strain.     

A healthy reduction in oil consumption and carbon emissions

Reliance on oil as an energy source for private transportation produces increasingly unfavorable social, political and environmental conditions including climate change, dependence on foreign oil, and the need for difficult choices between oil production and protection of biological systems. At the same time, the population is increasingly sedentary due largely to our reliance on the automobile for transportation. Adoption and maintenance of healthy weights and healthier lifestyles by substituting walking or biking for short trips currently taken by car could simultaneously improve health and reduce oil consumption and carbon dioxide emissions. We calculate the reduction in oil consumption and carbon dioxide emissions possible in the United States if (1) obese and overweight conditions were eliminated from the adult population through the use of walking or biking for transportation, and (2) individuals between the ages of 10 and 64 adopted previously recommended levels of daily exercise by walking or biking instead of driving. Substantial co-benefits accompany widespread adoption of physical activity. Assuming substitution of cycling for driving, the reduction in gasoline demand is equivalent to 34.9% of current domestic oil consumption. This constitutes considerably more oil than is recoverable from the Arctic National Wildlife Refuge. The concomitant reduction in US carbon dioxide emissions would constitute approximately 10.9% relative to 1990 net US emissions and would be a substantial step toward satisfying the Kyoto Protocol.     

Prediction of the daily performance of solar collectors

This paper presents the application of an online identification neural technique to the prediction of the in-situ daily performance of solar collectors. First, it is shown that the use of the Laplace transform helps to find the order of an approximated model; the input of the studied system being the solar radiation. Then it is shown that a Neural Network Output Error (NNOE) model can be accurate using the right size of the regression vector; the learning database consisting of the data obtained during a half day. Finally, it is shown that a Multiple Inputs Single Output (MISO) NNOE model can be accurate; the inputs being the solar radiation and the thermal heat loss conductance that varies with the wind velocity. In any case the differential between the actual value of the daily energy and the value computed by a neural model (SISO—Single Input Single Output) or MISO) is less than 0.5%.     

Performance review of a novel combined thermoelectric power generation and water desalination system

A novel combined thermoelectric power generation and water desalination system is described with a system schematic. The proposed system utilises low grade thermal energy to heat thermoelectric generators for power generation and water desalination. A theoretical analysis presents the governing equations to estimate the systems performance characteristics combined with experimental validation. Experimental set-up consists of an electric heat source, thermoelectric modules, heat pipes, a heat sink and an evaporator vessel. Four heat pipes are embedded in a heat spreader block to passively cool the bottom side of the thermoelectric cells. The condenser of these four heat pipes is immersed in a pool of saline water stored in an evaporation vessel which is maintained at sub-atmospheric pressure. The liquid to vapour phase change cooling method achieve low saturation temperature and offers a high heat transfer coefficient for the cooling of the thermoelectric generators. At the same time this method utilises the low temperature heat extracted from the cold side of the thermoelectric generator for water desalination. It was observed that at low saturation temperatures greater heat flux could be supplied to the thermoelectric generators with less heat losses to the atmosphere.     

Acceptance of biomass plants – Results of a longitudinal study in the bioenergy-region Altmark

The present contribution addresses the results of a longitudinal study in a ‘bioenergy-region’ concerning the public acceptance of biomass plants and the corresponding influencing factors. Using a standardized questionnaire, 423 persons were polled between 2009 and 2011 on three points of measurement in four places in the bioenergy-region Altmark. One main result of the study is that the reported public acceptance remains constantly high over time; nevertheless it became evident that the respective influencing factors differ in their strength, whereas the perceived regional benefit shows a strong connection to the reported public acceptance of biomass plants at each point of measurement. Concluding the research results, the acceptance of biomass plants doesn't seem to be a fixed construct, but has to be seen in context of the respective experiences with plants on a local level over time.In addition to the local population, key actors of the regional biomass sector were also interviewed (N = 26). The analyses show significant differences in the perception and evaluation of the current informational level between the population and the key actors. Furthermore, the key actors estimated the utilisation of biomass even more positively and expected a greater ‘signal function’ of the bioenergy-region-project compared to the population.     

Integrated sizing and scheduling of wind/PV/diesel/battery isolated systems

In this paper we address the optimal sizing and scheduling of isolated hybrid systems using an optimization framework. The hybrid system features wind and photovoltaic conversion systems, batteries and diesel backup generators to supply electricity demand. A Mixed-Integer Linear Programming formulation is used to model system behavior over a time horizon of one year, considering hourly changes in both the availability of renewable resources and energy demand. The optimal solution is achieved with respect to the minimization of the levelized cost of energy (LCOE) over a lifetime of 20 years. Results for a case study show that the most economical solution features all four postulated subsystems.     

Catalytic hydrodeoxygenation and hydrocracking of Alcell® lignin in alcohol/formic acid mixtures using a Ru/C catalyst

The catalytic conversion of Alcell^® lignin in iso-propanol/formic acid mixtures (1:1 mass ratio) was explored in a batch set-up using Ru/C as the catalyst (673 K, 4 h, 28% mass lignin intake on solvent). Lignin oils were obtained in good yields (71% mass yields on lignin input) and shown to consist of a mixture of mainly aromatics (10.5% mass yields on lignin input), alkylphenolics (6% mass yields on lignin input), catechols (8.7% mass yields on lignin input), guaiacols (1.3% mass yields on lignin input), and alkanes (5.2% mass yields on lignin input), the remainder being soluble higher molecular weight compounds (GCxGC-FID and GPC). The results for the catalytic experiments using formic acid were compared with those of a non-catalysed experiment and a catalytic hydrotreatment with molecular hydrogen and Ru/C in the absence of a solvent. Distinct differences in product yields and compositions were observed, and highest lignin oil yields were obtained by catalytic solvolysis (71% mass yields on lignin input) versus 18% mass yields on lignin input for non-catalytic solvolysis and 63% mass yields on lignin input for catalytic hydrotreatment. The effect of reaction time on oil yields and product composition was established and a reaction network involving depolymerisation, and hydro(-deoxy)genation pathways is proposed to explain the product yields and composition. Besides iso-isopropanol, the use of ethanol and methanol in combination with formic acid was also explored for catalytic solvolysis. Best results were obtained in methanol (4 h, 673 K) leading to a lignin oil (68% mass yields on lignin input) containing 11% mass yields on lignin input of alkylphenolics and 19% mass yields on lignin input of aromatics.