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Food Microbiology - Nonthermal Technologies

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1. Please mention 5 nonthermal technologies to process foods and thoroughly describe all of them.

2. Please explain the Preservation of Foods by Oscillating Magnetic Fields. Please provide a critical evaluation of this technology. Explain the possible mechanism of microbial inactivation by this approach.

3. Please sketch the design of a plant to process juices using Pulsed Electric Fields. The plant should have a capacity to process 5000 liters per our. Please try to be as realistic as possible and document as much as possible your design.

4. Please explain two possible approaches to design a high pressure vessel. Please provide as much details as possible.

5. Please define bacteriocins and mention at least three with potential food applications. Please describe in details how the microbial inactivation takes place.

Note: please write all references.

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Solution Summary

The solution discusses food microbiology and non-thermal technologies.

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1. Please mention 5 nonthermal technologies to process foods and thoroughly describe all of them.
A number of novel thermal and nonthermal processing methods are in active research and development in industry, academic and government laboratories. A key step that needs to be addressed is how to best package commodities processed by high pressure, pulsed electric fields, UV, irradiation, microwave or radio frequency heating, bioactive coating/packaging, or the treatment with probiotics to best preserve the benefits of improved product quality imparted by these emerging preservation technologies.
Packaging for Nonthermal Processing of Food reviews typical non-thermal processes, the characteristics of food products after non-thermal treatments, and packaging parameters to preserve the quality and/or enhance the food safety of the products.
As you know, the bacteria problem is a significant one facing food processors. While the incidence of traditional foodborne diseases, like trichinosis from undercooked pork and botulism from improperly canned foods, seems to be generally on the decline, each year millions of people become sick from disease-causing bacteria or viruses in poultry, shellfish and red meat.
In addition, emerging pathogens represent a major health risk to consumers. E. coli O157:H7 is one such pathogen. Historically, ground beef products have been associated with this type of E. coli, and most current beef burger manufacturing procedures do not adversely affect the survival of the organism.
Pulsed electric fields
High hydrostatic pressure
Light pulses
Electron beams
Steam pasteurization
Highlights include:
• Use of high pressure, pulsed electric fields ozone
• New opportunities, products and markets for pasteurized products
• Commercialization and case studies for these technologies
• High pressure processing applications and costs
• Pulsed electric fields applications and costs
• Ozone treatment applications and costs
• Combined processes and hurdle technology

1. High Pressure Processing (HPP) is rapidly becoming the most well known emerging non-thermal food processing technology based on its ability to produce value-added and fresher foods. HPP has the ability to safely inactivate Clostridium botulinum spores and other potentially harmful pathogenic microorganisms without compromising food structure or food quality, and breakthroughs for exploiting HPP to produce sterile (i.e., shelf-stable) low-acid foods are imminent that will significantly impact the commercial marketplace. Effecting sterilization with HPP requires an understanding of the relevant process control parameters (pressure, temperature, time, and characteristics of the food matrix) and their interactions with target pathogenic bacterial spores.
In High Pressure Processing of Foods, an array of international experts interrelate leading scientific advancements that use molecular biology techniques to explore the biochemical mechanisms of spore germination and inactivation by high pressure; investigate the inactivation of different spore species as functions of processing parameters such as pressure, temperature, time, food matrix, and the presence of anti-microbials; propose predictive mathematical models for predicting spore inactivation in foods treated with HPP; address commercial aspects of high pressure processing that include the high pressure equipment and packaging used to achieve the sterilization of bacterial spores in foods; and provide an assessment of the quality of food products preserved by HPP. High Pressure Processing of Foods is the landmark resource on the mechanisms and predictive modeling of bacterial spore inactivation by HPP.

2. Pulsed electric field (PEF) processing is a non-thermal method of food preservation that uses short bursts of electricity for microbial inactivation and causes minimal or no detrimental effect on food quality attributes. PEF can be used for processing liquid and semi-liquid food products.
PEF processing involves treating foods placed between electrodes by high voltage pulses in the order of 20-80 kV (usually for a couple of microseconds). The applied high voltage results in an electric field that causes microbial inactivation. The electric field may be applied in the form of exponentially decaying, square wave, bipolar, or oscillatory pulses and at ambient, sub-ambient, or slightly above-ambient temperature. After the treatment, the food is packaged aseptically and stored under refrigeration.
PEF treatment has lethal effects on various vegetative bacteria, mold, and yeast. Efficacy of spore inactivation by PEF in combination with heat or other hurdles is a subject of current research. A series of short, high-voltage pulses breaks the cell membranes of vegetative microorganisms in liquid media by expanding existing pores (electroporation) or creating new ones. Pore formation is reversible or irreversible depending on factors such as the electric field intensity, the pulse duration, and number of pulses. The membranes of PEF-treated cells become permeable to small molecules; permeation causes swelling and eventual rupture of the cell membrane.
Application of PEF technology has been successfully demonstrated for the pasteurization of foods such as juices, milk, yogurt, soups, and liquid eggs. Application of PEF processing is restricted to food products with no air bubbles and with low electrical conductivity. The maximum particle size in the liquid must be smaller than the gap of the treatment region in the chamber in order to ensure proper treatment. PEF is a continuous processing method, which is not suitable for solid food products that are not pumpable. PEF is also applied to enhance extraction of sugars and other cellular content from plant cells, such as sugar beets. PEF also found application in reducing the solid volume (sludge) of wastewater.
In general, the shelf-life of PEF-treated and thermally pasteurized foods is comparable. PEF pasteurization kills microorganisms and inactivates some enzymes and, unless the product is acidic, it requires refrigerated storage. For heat-sensitive liquid foods where thermal pasteurization is not an option (due to flavor, texture, or color changes), PEF treatment would be advantageous.
PEF pasteurized products currently are stored refrigerated. In some cases (for example, milk), this is necessary for safety (to prevent the growth of spores in low-acid foods). For acid foods, refrigeration is not necessary for microbial stability, but is used to preserve flavor quality for extended periods of time.

3. Ozone treatment:
Ozone kill bacteria disease pathogen, fresh perishable food fruit vegetable produce fish meat air water application. Spoilage organism like bacteria, fungus, mold spore, virus reduce product shelf life.
Spoilage organisms thrive, multiply faster at higher temperatures, high humidity. Many of these spoilage organisms and food pathogens will multiply at lower temperatures during refrigeration. Most cross contamination occurs on fresh produce during cold storage.
Chemicals used in air and water treatment has a negative impact on humans, as well as the environment. Ozone air water treatment is the most effective natural bactericide of all the disinfect or purification agents for bacteria or food pathogens.
Best available technology and a better alternative than using chlorine for purification in food processing.
Used in fresh perishable food processing or cold storage on fresh produce as an anti-microbial agent or as a food processing aid it will benefit all perishables, all phases of food processing or preparation, help prevent disease from food pathogens and enhance the quality of the working environment at the same time. The cleaner breathing environment raises worker productivity with fewer accidents.
Ozone is the safest and most natural purification and disinfectant agent for fresh produce and water treatment. It is the strongest and most ideal anti-microbial, bactericide, fungicide, deodorizer, detoxify agent, germicide, sanitizer, sterilizer and vermicide agent.
Unsurpassed for control of common food pathogens and others such as Cryptosporidium, E-coli, Fecal Coliform, Listeria, and deactivation of virus or cysts. Most everyone has read the problems associated with E-coli. Food pathogens can KILL.
Fruits vegetables in their growth stage are subjected to activated oxygen. The lack of it causes spoilage organisms and food pathogens to multiply which causes decay and sickness.
Chemical reaction and process of plant cells in the presence of light, change formaldehyde into plant sugar. The granules produced, starches are called plant quantasomes which are present within the chromosome, and are postulated to be the units of photosynthesis during this reaction.
Photosynthesis begins with plant quantasomes and quanta light. The waste ...

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