Thermal properties of bacterial spores and biopolymers

Differential scanning calorimetry (DSC) measurements of dormant bacterial spores is traditionally associated with an endothermic transition at around 50 degrees C. This endothermic transition was described as an indicator for two main physico-chemical states in spores. These were a glassy state in the dormant spore core as a model for spore dormancy and a heat-activated state that generally facilitates spore resuscitation. The idea of a glassy state in dormant spores is based on the observation that a similar transition as in dormant spores was observed in low moisture biopolymers that are in a glassy state. Thermal properties of spores of Bacillus subtilis and B. cereus in a dormant and germinated, resuscitated state and of an outer and an inner coatless spore mutant of B. subtilis were investigated. Biopolymers with low moisture (<15%) and high moisture (>30%) contents such as maize starch, pectin, RNA and DNA were further studied. Critical evaluation of results revealed that the low temperature transition in dormant spores has some similarities to those observed in glassy biopolymers, but also to those of fully hydrated proteins and therefore does not necessarily indicate a glassy low moisture state. Its origin can also be attributed to the outer spore coats and it occurred at a lower temperature and for a shorter duration to be of significance for thermal heat activation of spores.     

Antimicrobial resistance profile of five major food-borne pathogens isolated from beef, pork and poultry

This study was performed to evaluate the resistance rate against antimicrobials of food isolates of the five major food-borne pathogens to compare these and to possibly distinguish a pattern. A total of 922 samples of the major meat species (pork, beef and poultry) were analysed for thermophilic Campylobacter, Salmonella, Yersinia enterocolitica, pathogenic Escherichia coli and Listeria monocytogenes. Isolates were subjected to antimicrobial resistance testing by the disc diffusion method. Roughly the same overall rate of resistance was identified for thermophilic Campylobacter, Salmonella and pathogenic E. coli. Resistance to quinolones and tetracycline was determined most frequently. In contrast, food isolates of Y. enterocolitica and L. monocytogenes were rarely tested resistant. The significance of our findings is that resistance rates in enteric bacteria seem to be much higher than in pathogens found in a variety of environments, closely associated to the host environment.     

Functional, Nutritional, and Rheological Properties of Protein Powders from Arrowtooth Flounder and their Application in Mayonnaise

ABSTRACT: Arrowtooth flounder soluble protein powder (AFSP) and arrowtooth flounder insoluble protein powder (AFISP) were evaluated for their functional, nutritional, and rheological properties. AFSP and AFISP contained 80% and 79% protein and 5.9% and 14.9% fat, respectively. Yield of AFSP (8.6%) was less than AFISP (13.1%). AFSP and AFISP had desirable essential amino acid and mineral contents. Emulsion stability of AFSP was greater than AFISP. Fat and water absorptions (mL/g protein) were 5.2 and 1.8 for AFSP, respectively, and 3.3 and 4.2 for AFISP Mayonnaises made from AFSP had greater emulsion stability than mayonnaise made from AFISP. Mayonnaises from both AFSP and AFISP possessed pseudoplastic and viscoelastic characteristics.     

Quinone emissions from gasoline and diesel motor vehicles

Gas- and particle-phase emissions from gasoline and diesel vehicles operated on chassis dynamometers were collected using annular denuders, quartz filters, and PUF substrates. Quinone species were measured using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization in conjunction with gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry. Nine quinones were observed, ranging from C6 to C16. New species identified in motor vehicle exhaust include methyl-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone (MNQN), and aceanthrenequinone. Gas-phase motor vehicle emissions of quinones are also reported for the first time. Six gas-phase quinones were quantified with emission rates of 2-28 000 microg L(-1) fuel consumed. The most abundant gas-phase quinones were 1,4-benzoquinone (BON) and MNQN. The gas-phase fraction was > or = 69% of quinone mass for light-duty gasoline emissions, and > or = 84% for heavy-duty diesel emissions. Eight particle-phase quinones were observed between 2 and 1600 microg L(-1), with BQN the most abundant species followed by 9,10-phenanthrenequinone and 1,2-naphthoquinone. Current particle-phase quinone measurements agree well with the few available previous results. Further research is needed concerning the gas-particle partitioning behavior of quinones in ambient and combustion source conditions.     

Double Layer Coatings: A New Technique for Maintaining Physico-Chemical Characteristics and Antioxidant Properties of Dragon Fruit During Storage

A double layer coating was evaluated for maintenance of quality of dragon fruit during storage at 10?±?2 °C and 80?±?5 % RH for 28 days. Significant differences (p?<?0.05) were observed between control and the treated fruit. However, a double layer coating with 600 nm droplet size?+?1.0 % conventional chitosan showed promising results in all the tested parameters, while the fruit treated with 1,000 nm droplet size?+?1.0 % conventional chitosan showed some negative effects on fruit surface. Increase in weight loss was 12.0 % in fruit treated with 600 nm droplet size and 1.0 % conventional chitosan as compared to the control. Antioxidants and gaseous analysis also proved the efficacy of double layer coatings with 600 nm droplet size?+?1.0 % conventional chitosan. Thus it can be concluded from the present investigation that double layer coating could be used for maintaining quality in dragon fruit for up to 28 days without any off-flavours.     

Physicochemical Properties of Microencapsulated ω‐3 Salmon Oil with Egg White Powder

The objective of this study was to produce microencapsulated omega(ω)‐3 fatty acids (PUFAs) fortified egg white (EW) powders and to characterize their nutritional and physical properties. Stable emulsions (E‐SO‐EW) containing 3.43 (g/100 g) salmon oil (SO), 56.21 (g/100 g) EW, and 40.36 (g/100 g) water and a control (E‐EW) containing EW and water were prepared. E‐SO‐EW and E‐EW were separately spray dried at 130, 140, and 150 °C inlet air temperatures. This resulted in 3 microencapsulated SO fortified EW powders (SO‐EW), and 3 dried EW powders (DEW). The powders were analyzed for microencapsulation efficiency (ME), color, fatty acids methyl esters, protein, fat, moisture, ash, amino acids, minerals, microstructure, and particle size. The EPA and DHA content of SO and the ME of the powders were not affected by the inlet air temperature. The crude protein content of SO‐EW powders was approximately 24 (g/100 g) lower than dried EW powders. Leucine was the most abundant essential amino acid found in all the powders. Most of the powders’ median particle size ranged from 15 to 30 μm. The study demonstrated that microencapsulated ω‐3 salmon oil with high quality EW protein can be produced by spray drying.     

Long‐term testing of a high temperature polymer electrolyte membrane fuel cell: The effect of reactant gases

The investigations have been conducted with different oxidants and fuels with the aim of determining the state‐of‐the‐art of commercially available high temperature polymer electrolyte fuel cells based on polybenzimidazole for its application in combined heat and power generation systems. The fuel cell test performed with synthetic reformate (?63 μV/h) showed an increase of anode charge and mass transfer resistances. This behavior has suggested that CO may be generated from the CO₂ included in the synthetic reformate via reverse water gas shift reaction. The fuel cell test performed with pure O₂ developed the highest degradation rates (?70 μV/h) due to fast oxidative degradation of membrane electrode assembly materials such as cathode catalyst and membrane. Fuel cell operation with H₂/air exhibited the lowest degradation rates (?57 μV/h) and it requires longer investigating times to identify the different degradation mechanisms. Moreover, fuel cell tests performed with air suggested longer break‐in procedures to complete catalyst activation and redistribution of electrolyte. © 2015 American Institute of Chemical Engineers AIChE J, 62: 217–227, 2016     

Environmental aspects of metals removal from waters and gold recovery

Mining and metals processing are not invisible activities and are heavy industries, which require energy, water, chemicals, and land area. Recently more emphasis is given to environmental and societal aspects in mining and processing. Development of good practices with improved resource efficiency, new recovery methods and sustainability thinking are increasingly required. This work shows pH titration method for acid mine drainage (AMD) water incorporated with aqueous thermodynamic model for selective metals precipitation from complex solution. Also two examples on gold recovery methods from aqueous streams are shown: biosorption using fungal matter and solvent extraction using a task‐specific ionic liquid. By understanding chemical thermodynamics and natural phenomena, there is a better chance of developing solutions for environmental problems and new industrial processes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2739–2748, 2015     

Using short‐term resource scheduling for assessing effectiveness of CCS within electricity generation subsector

A new methodology for assessing the effectiveness of carbon capture and storage (CCS) that does explicitly consider the detailed operation of the target electricity system is proposed. The electricity system simulation consists of three phases, each one using a modified version of an economic dispatch problem that seeks to maximize the producers’ and consumers’ surplus while satisfying the technical constraints of the system. The economic dispatch is formulated as a dynamic mixed‐integer nonlinear programming problem and implemented in general algebraic modelling system (GAMS). The generating unit with CCS is designed and simulated using Aspen Plus®. In the first case study, the operation of the IEEE RTS ’96 (Institute of Electrical and Electronics Engineers One‐Area Reliability Test System—1996) is simulated with greenhouse gas (GHG) regulation implemented in the form of CO₂ permits that generators need to acquire for every unit of CO₂ that it is emitted. In the second case study, CCS is added at one of the buses and the operation of the modified IEEE RTS ’96 is again simulated with and without GHG regulation. The results suggest that the detailed operation of the target electricity system should be considered in future assessments of CCS and a general procedure for undertaking this for any GHG mitigation option is proposed. Future work will use the novel methodology for assessing the effectiveness of generating units with flexible CO₂ capture. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4210–4234, 2015