Effect of temperature and water activity on growth and ochratoxin A production boundaries of two Aspergillus carbonarius isolates on a simulated grape juice medium

Aims: To develop and validate a logistic regression model to predict the growth and ochratoxin A (OTA) production boundaries of two Aspergillus carbonarius isolates on a synthetic grape juice medium as a function of temperature and water activity (aw)

High-pressure processing, microwave, ohmic, and conventional thermal pasteurization: Quality aspects and energy economics

© 2019 The Authors. Journal of Food Process Engineering published by Wiley Periodicals, Inc. In this work, we collect and compare product quality data (vitamin C and flavor compounds) for orange juice processed using conventional thermal and innovative (high pressure, microwave, and ohmic) technologies under commercially representative conditions. We also measure and compare their respective energy demands and associated costs. While significant efficiency gains are made due to electrification using the innovative technologies (especially the ohmic process), the high per-unit costs of grid electricity results in poorer processing economics relative to conventional gas-fired technologies. UK levelized cost of electricity (LCOE) data suggest that as the share of renewables in the electricity generation energy mix is increased, the innovative technologies will eventually become more economical, in addition to the significant greenhouse gas emission reductions per liter of product. No significant differences are observed in the quality attributes of the processed product across all the technologies. The innovative electricity-driven technologies are thus promising alternatives to conventional thermal pasteurization. Practical applications: Beverage processing by conventional thermal treatment is energy consuming and can adversely affect the sensory and nutritional quality attributes of the final product. Innovative, mild processing techniques such as high-pressure processing, microwave, and ohmic heating are increasingly gaining industry attention due to their potentials to significantly address these challenges. Actual uptake is still relatively low due to factors including risk aversion, process validation issues, and economics. This work compares these technologies with conventional thermal treatment in terms of critical product quality attributes (vitamin C and flavor compounds) and process energy economics under commercially representative processing conditions. The results of this study will be useful as a guide to food processors for implementing the innovative technologies and could lead to new product development and process optimization.Research Councils UK. Grant Number: EP/K011820/

Temperature and energy performance of open refrigerated display cabinets using heat pipes shelves

In this paper an innovative design of open display cabinet’s shelves, based on flat heat pipe technology is presented. Their influence on the energy consumption of the cabinet and their effect on enhancing the preservation conditions of food products are analysed, as well. The experimental work was carried out using two identical commercial open display cabinets; one cabinet equipped with conventional/commercial shelves while the other one equipped with the new actively-cooled flat heat pipe shelves. Both cabinets were placed inside an ISO-certified environmentally controlled test chamber and experiments were carried out under stable environmental conditions of 20°C temperature and 50% humidity (ISO Class 0). Food block simulators and real food products were used for the tests. The temperature distribution inside the real food products and the power consumption of the cabinets were measured for the cabinets’ set point of 2.0°C. The experimental outcomes were that the use of the heat pipe shelves can homogenise the temperature profile of the products, reduce the air temperature variations inside the cabinet’s void and improve the heat transfer between the cabinet, the shelves and the products. Moreover, the heat pipe shelves facilitated the reduction of the electrical energy consumption of the cabinet by 12% approximately, which paves the way to a very reasonable commercial case for the new shelf design. Finally, in order to investigate the possibility of these selves extending the self-life of foodstuffs, a primary analysis examining the acidity levels (pH) of the products was conducted. The experiments showed that almost all products placed on the heat pipe shelves, after 21 days of experiments, had almost the same pH values, even 20 days beyond their expiration date.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Feasibility study of biomass gasification integrated with reheating furnaces in steelmaking process

This paper investigates the integration of biosyngas production, reheating furnace and heat recovery steam cycle, in order to use biosyngas directly as fuel in the furnace. A system model was developed to evaluate the feasibility of the proposed system from the perspective of heat and mass balance. To particularly study the impacts of fuel switching on the heating quality of the furnace, a three-dimensional furnace model considering detailed heat transfer processes was embedded into the system through an Aspen PlusTM user defined model. The simulation results show that biosyngas is suitable for direct use as fuel for reheating furnaces. Should CO capture be considered in the proposed system, it has a potential to achieve the capture without external energy input which results in so-called negative emissions of CO

Molecular characterization of piezotolerant and stress resistant mutants of Staphylococcus aureus

Aims In previous work, following a pressure treatment of S. aureus wild type, we obtained piezotolerant isolates showing altered phenotypic characteristics. This work focuses on understanding the genetic background of their altered phenotype. Methods and Results AK23, a representative piezotolerant isolate was subjected to DNA microarrays, corroborated by PCR product sequencing and revealed 10-gene deletion. All other piezotolerant isolates possessed the mutation encompassing the region from SAR0665 to SAR0674 genes (9351 bp) which was most likely the result of recombination between two homologous loci (ATTGCGGGTG) present in both genes. RNA microarray transcriptomic analysis showed that due to partial deletion of the low-affinity phosphate transporter pitA, the high-affinity PhoU-PstABCS operon was upregulated in AK23 which could be the reason for piezotolerance. Furthermore, AK23 showed low levels of the virulence gene regulator rnaIII resulting in the downregulation of several agr system genes explaining the impaired virulence characteristics of the mutant. Conclusions Naturally-occurring mutations can result in piezotolerance which can be of a concern for High Hydrostatic Pressure-treated foods. Significance and Impact of Study A locus has been identified in piezotolerant S. aureus mutants providing insight in possible mechanisms associated with phenotypic characteristics of S. aureus. Further work should study each individual gene of the locus

Partialization losses of ON/OFF operation of waterto- water refrigeration/heat-pump units

[EN] This paper presents the results of an experimental campaign for the characterization of the dynamic behavior of a water-to-water refrigeration/heat-pump unit under ON/OFF operation. The unit was previously tested at different water inlet temperatures under steady state conditions, and a very good agreement was found between the instantaneous dynamic performance of the heat pump and the corresponding quasi-steady state operation. In parallel, a series of tests were carried out to quantify the coefficient of performance (COP) degradation as a function of the load ratio, and a simple formula for the Part Load Factor is presented. Results lead to the conclusion that the only non-negligible factor in the COP degradation is the stand-by electrical consumption during the OFF period, especially at low load ratios. Finally, it is concluded that the minimization of the stand-by consumption is a key point for the future improvement of the seasonal performance of water-to-water systems.This research has been partially funded by the European FP7 framework project "Advanced ground source heat pump systems for heating and cooling in Mediterranean climate" (GROUND-MED) and the Spanish Ministry of Economy and Competitiveness (MINECO) through the project "Estudio de evaporadores y condensadores basados en tecnologia de minicanales para su aplicaciOn en equipos de aire acondicionado, refrigeraciOn y bomba de calor estacionarios" with reference DPI2011-26771-C02-01. The authors gratefully acknowledge their financial support.Corberán, JM.; D.Donadello; Martínez Galván, IO.; Montagud, C. (2013). Partialization losses of ON/OFF operation of waterto- water refrigeration/heat-pump units. International Journal of Refrigeration. 36(8):2251-2261. https://doi.org/10.1016/j.ijrefrig.2013.07.002S2251226136

Greenhouse gas emissions from a Western Australian finfish supply chain

Greenhouse gas (GHG) emissions in the form of carbon dioxide equivalent (CO2 - eq) from two Western Australian finfish supply chains, from harvest to retail outlet, were measured using streamlined life cycle assessment methodology. The identification of interventions to potentially reduce the GHG emissions was determined from the results obtained. Electricity consumption contributed to the highest GHG emissions within the supply chains measured, followed by refrigeration gas leakage and disposal of unused fish portions. Potential cleaner production strategies (CPS) to reduce these impacts included installing solar panels, recycling the waste, good housekeeping in refrigeration equipment maintenance, and input substitution of refrigeration gas. The results show a combination of these strategies have the potential to reduce up to 35% of the total GHG emissions from fillet harvest, processing and retail

Is there a common water-activity limit for the three domains of life?

Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (a w) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a w. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a w). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 a w for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a w for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life

Validation of the OECD reproduction test guideline with the New Zealand mudsnail Potamopyrgus antipodarum using trenbolone and prochloraz

The Organisation for Economic Cooperation and Development (OECD) provides several standard test methods for the environmental hazard assessment of chemicals, mainly based on primary producers, arthropods, and fish. In April 2016, two new test guidelines with two mollusc species representing different reproductive strategies were approved by OECD member countries. One test guideline describes a 28-day reproduction test with the parthenogenetic New Zealand mudsnail Potamopyrgus antipodarum. The main endpoint of the test is reproduction, reflected by the embryo number in the brood pouch per female. The development of a new OECD test guideline involves several phases including inter-laboratory validation studies to demonstrate the robustness of the proposed test design and the reproducibility of the test results. Therefore, a ring test of the reproduction test with P. antipodarum was conducted including eight laboratories with the test substances trenbolone and prochloraz and results are presented here. Most laboratories could meet test validity criteria, thus demonstrating the robustness of the proposed test protocol. Trenbolone did not have an effect on the reproduction of the snails at the tested concentration range (nominal: 10-1000 ng/L). For prochloraz, laboratories produced similar EC10 and NOEC values, showing the inter-laboratory reproducibility of results. The average EC10 and NOEC values for reproduction (with coefficient of variation) were 26.2 µg/L (61.7%) and 29.7 µg/L (32.9%), respectively. This ring test shows that the mudsnail reproduction test is a well-suited tool for use in the chronic aquatic hazard and risk assessment of chemicals