Commercial Food Processing Operations and Mutagen Formation

1987 ◽  
Vol 50 (2) ◽  
pp. 167-174 ◽  
Author(s):  
CHERYL A. KRONE ◽  
WAYNE T. IWAOKA
Keyword(s):  
Pink Salmon ◽  
Food Preservation ◽  
Thermally Induced ◽  
Muscle Foods ◽  
Evaporative Concentration ◽  
Mutagenicity Assay ◽  
Canned Foods ◽  
Spontaneous Revertant ◽  
Lower Temperature ◽  
Maillard Browning

Thermally-induced bacterial mutagens are formed when foods are processed by some commercial food preservation techniques. The processes which involve longer times and higher temperatures are most likely to produce mutagens (e.g., canning and evaporative concentration). Pasteurization and spray drying processes possess a low potential for creation of mutagens. The types of food products with the greatest tendency to contain mutagens following heat treatments are muscle foods such as canned meats and fish. Canned beef broth, chili, hash, roast beef, pink and red salmon, and mackerel contain substances which induce mutation rates up to 20 times higher than spontaneous revertant colonies in the Ames Salmonella mutagenicity assay. Using canned pink salmon as a representative product, reprocessing increased mutagen content, whereas addition of Maillard-browning reaction inhibitors led to significant decreases in mutagen formation. Even though thermally-induced mutagens can arise during household cooking (e.g., frying and charcoal grilling), the consumer can choose to minimize their production through use of lower temperature methods such as boiling, steaming or microwave heating. This option is not available to the consumer of commercially canned foods. Hence, further research into the reduction of mutagen formation during thermal processing is needed.

scholarly journals Performance Evaluation of Thermoelectric Refrigerator Using Peltier Effect

2021 ◽  
Vol 9 (8) ◽  
pp. 1171-1175
Author(s):  
Manjesh B C
Keyword(s):  
Performance Evaluation ◽  
Electrical Power ◽  
Food Preservation ◽  
Peltier Effect ◽  
Thermo Electric ◽  
Underdeveloped Countries ◽  
Extended Life ◽  
Lower Temperature

Abstract: The worldwide growth in call for refrigeration brought about the manufacturing of extra power and this, in turn, brought about extra use of CFCs. CFCs, in particular, are a notable factor in the ozone layer's depletion. TER (Thermoelectric Refrigerator) is a revolutionary option that eliminates the use of refrigerant. As a result, it is critical, especially in underdeveloped countries where extended life and inexpensive maintenance are required. The goal of this research is to design and build a functional TER that uses the Peltier effect to cool this volume to much lower temperature in under two hours and retain it for at least the next 1/2 hour. In this project, we created a TE system that works with both solar and electrical power. Food preservation, military or aerospace equipment, medicinal and pharmaceutical equipment are just some of the uses for the project. Keywords: Thermo-electric Refrigerator, CFCs, COP, Peltier Effect

Mechanical Integrity Issues of Fuel Cells

2003 ◽  
Author(s):  
Rowland P. Travis
Keyword(s):  
Fuel Cells ◽  
Residual Stresses ◽  
Operating Temperature ◽  
Medium Temperature ◽  
Thermally Induced ◽  
Factors Affecting ◽  
Mechanical Integrity ◽  
Entire Structure ◽  
Lower Temperature ◽  
Differential Expansion

The conditions under which fuel cells are required to operate apply constraints upon the components and the entire structure of a fuel cell. These can then affect the mechanical integrity of the cells. For high and medium temperature cells such conditions might include differential expansion due to thermal property mismatch of the materials in the cell, residual stresses after manufacture and material behaviour such as creep at temperature. For lower temperature cells the effects of hydration expansion and contraction may introduce significant effects. However, to date, there has been little concentration on the mechanical integrity of fuel cells because of the paramount initial consideration of developing the technology itself, particularly from and electrical and materials standpoint. The aim of this paper is to summarise some of the factors affecting the mechanical integrity fuel cells and the work conducted to assess these at Imperial College London. Residual stresses due to thermal expansion mismatch after cooling during manufacture are evaluated; creep in high-temperature cells due to the operating temperature is measured, and thermally induced stresses due to temperature variations are predicted by a combination of thermo-mechanical computational-fluid dynamics and experimental work. The results are indicative of considerable stresses within the fuel cells and identify mechanical integrity as a significant issue.

Temperature and Flux dependence of ion induced ripple: a way to study defect and relaxation kinetics during ion bombardment

2004 ◽  
Vol 849 ◽  
Author(s):  
Wai Lun Chan
Keyword(s):  
High Temperature ◽  
Surface Defect ◽  
Ion Beam ◽  
Linear Instability ◽  
Low Energy ◽  
Ion Sputtering ◽  
Thermally Induced ◽  
Formation Kinetics ◽  
Lower Temperature Range ◽  
Lower Temperature

ABSTRACTWe have measured the temperature and ion flux dependence of the ripple wavelength on a Cu(001) surface during low energy ion sputtering. We analyze these results in terms of a linear instability model and identify different experimentally observed behavior with different mechanisms of relaxation and surface defect kinetics. In a high temperature regime, diffusing species on the surface are mainly thermally induced while in a lower temperature range, the diffusing species are ion beam induced. At even lower temperature, thermal diffusion is deactivated and the surface relaxes through an athermal mechanism. We define a transition between different defects formation kinetics in temperature and flux phase space and discuss how the defect kinetics model can be extended to different materials system.

scholarly journals New Insights on the Role of Urea on the Dissolution and Thermally-Induced Gelation of Cellulose in Aqueous Alkali

Gels ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 87 ◽  
Author(s):  
Luis Alves ◽  
Bruno Medronho ◽  
Alexandra Filipe ◽  
Filipe E. Antunes ◽  
Björn Lindman ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Three Dimensional ◽  
Aqueous Alkali ◽  
Characterization Methods ◽  
Thermally Induced ◽  
Alkali Solutions ◽  
Cellulose Fibrils ◽  
Lower Temperature ◽  
Dissolution Efficiency

The gelation of cellulose in alkali solutions is quite relevant, but still a poorly understood process. Moreover, the role of certain additives, such as urea, is not consensual among the community. Therefore, in this work, an unusual set of characterization methods for cellulose solutions, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR) and diffusion wave spectroscopy (DWS) were employed to study the role of urea on the dissolution and gelation processes of cellulose in aqueous alkali. Cryo-TEM reveals that the addition of urea generally reduces the presence of undissolved cellulose fibrils in solution. These results are consistent with PTssNMR data, which show the reduction and in some cases the absence of crystalline portions of cellulose in solution, suggesting a pronounced positive effect of the urea on the dissolution efficiency of cellulose. Both conventional mechanical macrorheology and microrheology (DWS) indicate a significant delay of gelation induced by urea, being absent until ca. 60 °C for a system containing 5 wt % cellulose, while a system without urea gels at a lower temperature. For higher cellulose concentrations, the samples containing urea form gels even at room temperature. It is argued that since urea facilitates cellulose dissolution, the high entanglement of the cellulose chains in solution (above the critical concentration, C*) results in a strong three-dimensional network.

Predicted Thermal Stresses in a Circular Assembly With Identical Adherends and With Application to a Holographic Memory Package Design

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
E. Suhir ◽  
C. Gu ◽  
L. Cao
Keyword(s):  
Elevated Temperature ◽  
Thermal Stresses ◽  
Memory Systems ◽  
Stress Model ◽  
Adhesively Bonded ◽  
Holographic Memory ◽  
Thermally Induced ◽  
Package Design ◽  
Induced Stresses ◽  
Lower Temperature

A simple, easy-to-apply and physically meaningful analytical (“mathematical”) stress model is developed for the prediction of the thermally induced stresses in a circular adhesively bonded assembly with identical adherends. The assembly is fabricated at an elevated temperature and is subsequently cooled down to a lower temperature. The developed model can be helpful for stress-strain analyses and physical design of electronic and photonic assemblies of the type in question, and particularly those employed in holographic memory systems.

scholarly journals Gıdalardaki Biyokoruyucu: Nisin (E234)

2015 ◽  
Vol 3 (12) ◽  
pp. 908
Author(s):  
Başar Uymaz ◽  
Pınar Şanlıbaba
Keyword(s):  
Antimicrobial Agents ◽  
Food Additives ◽  
Economic Loss ◽  
Food Preservation ◽  
Human Consumption ◽  
Successful Implementation ◽  
Food Preservatives ◽  
The Us ◽  
Canned Foods ◽  
New Generation

Fermentation is the oldest traditional method in order to protect against spoilage and pathogenic microorganisms. Thermal treatment, pH and water activity lowering and preservative addition other food preservation techniques that are commonly used. Although, as preservatives, many improved antibiotic and chemical agents have been gained, there are some other factors such as rapid resistance to antibiotics used in bacteria, in order to limit their use in food, to be found dimensions of threatening human health of the chemical protection and to cause allergic reactions. Recently, studies on bacteriocins that are produced by the safe bacteria, such as lactic acid bacteria, contain no toxic and adverse effects for human consumption have gained sudden intensity in accordance with the request against consumers in developing microbiologically safe and minimal processed food. There are some important effects using of bacteriocins accepted the new generation of antimicrobial agents as food preservatives such as extension of shelf life, reducing of the use of chemical preservatives and the economic loss caused degradation by microorganisms. Nisin, defined as GRAS (Generally Recognized as Safe) by FDA and named the E234 code 'Nisin-protective' or 'natural protective' located in the food additives list, first used in 1988 as a natural preservative by prohibiting of antibiotics using in food in the US. Nowadays in more than 50 countries, there have been more successful implementation of the nisin protected up the food from milk and dairy products to canned foods many food products

EPDM Vulcanization and High Temperature Compression Set

1970 ◽  
Vol 43 (5) ◽  
pp. 1040-1054 ◽  
Author(s):  
F. P. Baldwin
Keyword(s):  
High Temperature ◽  
Crosslink Density ◽  
Reduction Process ◽  
Exact Nature ◽  
Competitive Balance ◽  
Rank Reduction ◽  
Thermally Induced ◽  
Compression Set ◽  
Lower Temperature ◽  
Free Sulfur

Abstract The data presented are suggestive of the following conclusions regarding the vulcanization behavior and high temperature compression set properties of low unsaturation EPDM polymers: 1. The olefinic residue derived from ENB is more reactive in conventional sulfur vulcanization than is the residue from MNB. However, the ENB residue is more prone to reversion reactions. 2. The structure of the olefinic residue present can have important bearing on the exact nature at the crosslinks produced at a given crosslink density. 3. The conversion of high to lower sulfur rank crosslinks appears to occur partly by a thermally induced interconversion process and partly by concerted reactions in which crosslink bond scission does not occur as a discrete step. Both the nature and the concentration of accelerator present should have important bearing on the competitive balance between these two processes as should the presence of free sulfur. 4. Since the presence of free sulfur can procrastinate the sulfur crosslink rank reduction process, the observed low rate (relative to highly unsaturated elastomers) of conversion of polysulfidic to lower rank crosslinks must be associated with the absence of a large “sink” for sulfur. Thus with a given curing system, stable crosslinks should be generated faster the higher the level of unsaturation present and the lower the sulfur concentration. 5. High temperature compression set performance is influenced not only by the formation of new crosslinks during heating under compression but also by the interconversion of polysulfidic linkages present in the initial vulcanizates. Thus two polymers containing different olefin residues can exhibit identical set properties but for different reasons. 6. In practical terms both crosslink density and stability can be maximized by a combination of a short, high temperature forming cure followed by a long heat soak at a lower temperature. This observation should have important bearing on the economics of production of quality mechanical goods from low unsaturation elastomers via injection molding, the heat soaking step being paid for by the reduction in accelerator cost and molding cycle time.

Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

1972 ◽  
Vol 30 ◽  
pp. 524-525
Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit
Keyword(s):  
Electron Microscopy ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Substrate Surface ◽  
Morphological Features ◽  
Thermally Induced ◽  
Oxide Spallation ◽  
Oxidation Resistant ◽  
Induced Stresses ◽  
Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

Silicon Tetrachloride Synthesis from Rice Hulls: Transmission and Scanning Electron Microscope Study

1972 ◽  
Vol 30 ◽  
pp. 236-237 ◽  
Author(s):  
Richard S. Thomas ◽  
Prabir K. Basu ◽  
Francis T. Jones
Keyword(s):  
Silicon Tetrachloride ◽  
Silica Sand ◽  
Mineral Matter ◽  
Chemical Heterogeneity ◽  
Scanning Electron Microscope Study ◽  
Rice Hulls ◽  
Hull Structure ◽  
Lower Temperature ◽  
Image Position ◽  
Disposal Problem

Silicon tetrachloride, used in industry for the production of highest purity silicon and silica, is customarily manufactured from silica-sand and charcoal.SiCl4 can also be made from rice hulls, which contain up to 20 percent silica and only traces of other mineral matter. Hulls, after carbonization, actually prove superior as a starting material since they react at lower temperature. This use of rice hulls may offer a new, profitable solution for a rice mill byproduct disposal problem.In studies of the reaction kinetics with carbonized hulls, conversion of SiO2 to SiCl4 was found to proceed within a few minutes to a constant, limited yield which depended reproducibly on the ambient temperature of the reactor. See Fig. 1. This suggested that physical or chemical heterogeneity of the silica in the hull structure might be involved.

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