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.     

Dynamic analysis of growth of Salmonella Enteritidis in liquid egg whites

Salmonella Enteritidis (SE) is a common foodborne pathogen associated with eggs and egg products. This research was conducted to study the kinetics of growth and survival of SE in liquid egg whites (LEW). A dynamic temperature profile that exposed SE to suboptimal temperatures and below the minimum growth temperature (T_min) was used with two isothermal conditions to develop kinetic models. One-step dynamic analysis was used to directly construct a tertiary model for describing the growth and survival of SE and determine the kinetic parameters.The results of kinetic analysis showed that the T_min was 7.7 °C and SE may die off at a rate of 2.78 × 10⁻³ log CFU/ml per h per °C below the T_min. The root mean square error (RMSE) of the model was 0.5 log CFU/ml, with 76.6% of the residual errors within ±0.5 log CFU/ml of the experimental observations. The model was validated under both dynamic temperature and isothermal conditions. Both growth and survival of SE was accurately predicted, with the RMSE of validation at < 0.5 log CFU/ml. For all the validation tests, nearly 75% of the residual errors were within ±0.5 log CFU/ml of the experimental observations.This study clearly demonstrated that the one-step dynamic analysis method is an accurate and efficient method for direct construction of predictive models and estimation of the associated kinetic parameters that govern the growth and survival of microorganisms in food. Since the mathematical model has been validated, it can be used to predict the growth and survival of SE in LEW during storage and distribution and for conducting risk assessment of this microorganism.     

A survey on the Aflatoxin M1 occurrence and seasonal variation in buffalo and cow milk from Southern Italy

This study evaluates the aflatoxin M1 (AFM1) contamination in 804 samples of raw milk from cow and buffalo, collected randomly in Campania and Calabria regions of Southern Italy over a two years period.The competitive enzyme linked immunosorbent assay (ELISA) method was used to analyze AFM1 in the samples. AFM1 levels result above the CCβ value of 0.004 μg/kg in 51 (12.3%) cow milk samples and in 28 (7.2%) buffalo milk samples. Positive results from screening analysis were confirmed by high performance liquid chromatography with fluorimetric detection (HPLC-FLD) after a procedure of centrifugation, extraction and immunoaffinity column clean-up of milk. Only one cow milk sample exceeded the maximum limit (0.05 μg/kg) set by the European Regulation.The occurrence of AFM1 contamination was significantly (p < 0.05) higher in cold season, particularly fall, than in warm season, principally spring.Our results indicate that feedstuff used in the buffalo and cow farms were not highly contaminated with aflatoxins, determining a good quality of the analyzed milk. Therefore, the AFM1 contamination of the milk does not represent a serious public health problem in both regions in Southern Italy.     

Consumers’ familiarity with and attitudes towards food quality certifications for rice and vegetables in Vietnam

This study investigates consumers’ attitudes towards, and familiarity with, food quality certification in selected urban areas in the South of Vietnam. Cross-sectional data were collected by means of a consumer survey (n = 500). Consumers’ awareness of food quality-related terms was relatively low. Less than half the participants claimed to understand the meaning of good agricultural practices (GAP), organic food and sustainability. Consumers’ familiarity with food quality certification (Vietnamese Good Agricultural Practices (VietGAP), Global Good Agricultural Practices (GLOBALG.A.P.), organic, and Hazard Analysis and Critical Control Points (HACCP)) was also low. Familiarity with food quality certification was positively associated with general attitude and food choice motives, namely food safety concern, perceived importance of healthy eating, and perceived importance of environmental consequences relating to food purchase. Food safety concern and perceived importance of environmental consequences were positively associated with consumers’ attitudes towards safe vegetables, as well as high quality rice. Perceived importance of healthy eating was positively related to attitude towards high quality rice. Findings suggest that food safety aspects of safe vegetables and high quality rice should be emphasized during policy and marketing activities for food quality certification. Additionally, an increase in the perceived importance of environmental consequences relating to quality food purchase should be encouraged to enhance positive consumer attitudes towards quality food. Efforts to improve public awareness and knowledge of food quality certification and sustainable agricultural practices in developing countries such as Vietnam are highly recommended.     

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.