Explanation of Techniques in Identifying Food Borne Pathogens

Science-based pathogen-specific tests can be divided into the categories of traditional and rapid methods.Traditional microbiological methods involve enriching the food sample and performing various media-based metabolic tests (agar plates or slants). These typically require 3–7 days to obtain a result.
Borrowing from clinical laboratory methods, rapid-screening tests based on immunochemical or nucleic acid technologies have been developed for food testing. These tests can provide results in 8 to 48 hours.The three types of rapid-test methods are manual, semiautomated, and fully automated. Manual rapid-test methods include lateral-flow tests and dipstick immunoassays. Semiautomated methods include ELISA tests and enzyme-linked hybridization tests. Fully automated systems include instrumentation to perform either immunoassays or PCR methodologies.
Researchers have developed some new rapid technology that can detect food borne pathogens, such as electroimmunoassay technology and live cells technology.
Electroimmunoassays couple specific antibody-antigen binding to the production of an electrical signal. The technology is comprised of a circuit with a capture antibody attached to the solid surface in the area of the electrode gap Upon addition of sample, the target antigen binds to the capture antibody. In the next step, a colloidal gold–labeled detection antibody is bound, creating a capture-target-detector sandwich. The final step is the deposition of silver ions onto the colloidal gold, which produces a conductive silver bridge, closing the circuit and resulting in a measured drop in resistance. This detection technology can also be applied to nucleic acid hybridization assays.
In addition, the live cells technique utilizes live mammalian cells that release a measurable amount of a signaling chemical when harmed. Optical equipment and computer software can then analyze this quantity to estimate the amount of harmful microbes present, Bhunia said. The technology can recognize very small amounts of Listeria monocytogenes, a bacterium that kills one in five infected and is the leading cause of food-borne illness. It also recognizes several species of Bacillus, a non-fatal but common cause of food-poisoning. The cells are suspended in collagen gel, a useful substance for capturing particles of a desired size, and put into small wells within multi-well plates. Each well can test one sample, so tests can be expanded to quickly analyze as many samples as desired.
http://www.purdue.edu/UNS/x/2008a/080228BhuniaBiosensor.html
http://www.devicelink.com/ivdt/archive/01/06/003.html

Discussion on Environmental Concerns

There are some environmental concerns resulting from the application of GM crops. Some claimed that the results showed that GM crops had a significant negative impact on environmental, esp, wildlife. On the other hand, others points out that the studies showed that using herbicide resistant allowed better weed control and have a positive impact on environmental.
Unintended harm to other organisms
Last year a laboratory study was published in Nature showing that pollen from B.t. corn caused high mortality rates in monarch butterfly caterpillars. Unfortunately, B.t. toxins kill many species of insect larvae indiscriminately. Environmental Protection Agency (EPA) and other non-government research groups, and preliminary data from new studies suggest that the original study may have been flawed. Currently, there is no agreement about the results of these studies, and the potential risk of harm to non-target organisms will need to be evaluated further.
Reduced effectiveness of pesticides
Just as some populations of mosquitoes developed resistance to the now-banned pesticide DDT, many people are concerned that insects will become resistant to B.t. or other crops that have been genetically-modified to produce their own pesticides.
Gene transfer to non-target species
Another concern is that crop plants engineered for herbicide tolerance and weeds will cross-breed, resulting in the transfer of the herbicide resistance genes from the crops into the weeds. These superweeds would then be herbicide tolerant as well. Other introduced genes may cross over into non-modified crops planted next to GM crops. More investigation is needed to resolve this issue.
http://en.wikipedia.org/wiki/Genetically_modified_food_controversies
http://www.csa.com/discoveryguides/gmfood/overview.php

http://news.bbc.co.uk/olmedia/275000/images/_278243_maize.jpg

Discussion on Religious / Ethical Concerns

Food plays an important role in culture and societal life of human, and has religious and ethnical significance to people. Hence, GM foods resulting from the science and technology of genetic modification will be faced with social and ethical resistance.
In developed countries, surveys indicate that lack of information is not the primary reason for opposition to GM foods there. They are quite aware that their lives are full of risks that need to be balanced against each other and against the potential benefits. A key finding is that people do not react so much to genetic modification as a specific technology, but rather to the context in which GMOs are developed and the purported benefits they are to produce. However developing countries, lack of knowledge and awareness plays a significant role in opposition to GM foods.
One major point of arguments against GM crops is the ethical concern. Some people believe it is a violation of natural organisms’ intrinsic values. In addition, there are some other reasons including: tampering with nature by mixing genes among species; objections to consuming animal genes in plants and vice versa; stress for animal.
http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml
http://www.123biotech.com/gm-crops-ethical-concerns.shtml

http://www.non-gm-farmers.com/images/uploads/monster.JPG

Discussion on the Various Sources of GM Foods

The sources of GM foods can be classified into the categories as follow.
1. Corn products, which have not been guaranteed to be non-GM. These could include: textured vegetable protein, hydrolyzed vegetable protein, tofu, soya sauce, polenta and flours and meals made from soya or maize.
2. Derivatives of corn, cotton or oilseed rape, which have not been guaranteed to be non-GM. These could include: vegetable oil, soya derivatives such as soya oil, soya starch, soya fiber, lecithin and vitamin; maize derivatives such as corn oil, cornstarch, modified starch, starch-based granulation additives, corn syrup, xanthan gum and some brands of dextrose, glucose, dextrins, maltodextrins, sorbitol and ascorbic acid and some coating agents or carriers for vitamins, colours and flavours; cotton derivatives such as cottonseed oil; oilseed rape derivatives such as canola.
3. Honey or honey products, which may come from hives within six miles of a GM crop or test site. These products include: honey, propolis, beeswax, royal jelly and pollen.
4. GM micro-organisms or their products. GM micro-organisms include some bacteria, brewers yeasts and bakers yeasts. Products of GM bacteria include riboflavin, aspartame, possibly amino acids such as tryptophan and some of the following enzymes that are used as processing aids: Glucose oxidase, Hemicellulase, Lipase, triacylglycerol, Maltogenic amylase, Protease and Pullulanase. Products of GM yeasts include some yeast extracts, alcohol and fermented products.
5. Food additives, which may come from GM. These additives could include: Riboflavin (made by GM bacteria), Caramel colouring (from chemically treated sugars - can be made from GM cornstarch), Carbon Black (colouring from burnt plant matter - can inc GM crops).
6. Products of GM-fed or treated animals. Such products include meat, gelatin, milk, whey cheese, butter, eggs and albumen from animals raised on feed containing GM ingredients or injected with GM growth hormones such as BST.
http://www.geneticfoodalert.supanet.com/ingred.htm

Discussion of Controversial Issues on Product Labeling

Labeling of GM foods and food products is also a contentious issue. On one hand, the factories and companies believe that labeling should be voluntary and influenced by the demands of the free market. There are not mandatory regulations in some countries (e.g., United State). On the other hand, consumers also have the right to know what they are eating. Therefore, there many people think it is necessary to make mandatory regulations for labeling of GM foods. The European Union has brought in regulations for the mandatory labeling of genetically modified foods. We should take some sequences into account if labeling of GM foods becomes mandatory.

First, are consumers willing to absorb the cost of such an initiative? If the food production industry is required to label GM foods, factories and farmers will need to change the whole existing processing, storage, production of food, and policy correspondingly. The industry will pass along these additional costs to consumers in the form of higher prices.

Secondly, what are the acceptable limits of GM contamination in non-GM products? It has been determined that 1% is an acceptable limit of cross-contamination, yet many consumer interest groups argue that only 0% is acceptable. But who is going to monitor these companies for compliance and what is the penalty if they fail? In addition, Scientists agree that current technology is unable to detect minute quantities of contamination, so ensuring 0% contamination using existing methodologies is not guaranteed.

Finally, who is to be responsible for educating the public about GM food labels and how costly will that education be? Food labels must be designed to clearly convey accurate information about the product in simple language that everyone can understand. This may be the greatest challenge faced be a new food labeling policy: how to educate and inform the public without damaging the public trust and causing alarm or fear of GM food products. However, on the other hand, labeling could have positive effects. For example, the public could be familiarized with such new technologies as the slow-ripening tomato, which has been well received by consumers, when marketed and voluntarily labeled as genetically modified to slow the ripening process.

In a word, the labeling is a complex issue. We should not make a simple decision that the labeling will be mandatory or not. The actual GM foods industries and situation must be taken into account.

http://www.csa.com/discoveryguides/gmfood/overview.php
http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml
http://dsp-psd.tpsgc.gc.ca/Collection-R/LoPBdP/BP/prb9912-e.htm
http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml
http://www.gm.org/images/img_wp_quest.jpg

Discussion of Controversial Issues on Consumer Rights

The right of knowing the product. The consumers have rights to know what they are eating. Some GM foods occur due to the adoption of the genetically modified ingredients and the cross-contamination of other genetically modified food during the processing. But, for the cost of labeling, many producers don’t note whether the foods they sell are GM foods. Therefore, in fact the GM foods are not known clearly by consumers.

The right of health. The consumers have rights to know the concerns of GM foods and make a clear decision to choose or not choose GM foods by themselves. GM foods may pose the long term health risks to human. For instance, Many children in the US and Europe have developed life-threatening allergies to peanuts and other foods. There is a possibility that introducing a gene into a plant may create a new allergen or cause an allergic reaction in susceptible individuals. Extensive testing of GM foods may be required to avoid the possibility of harm to consumers with food allergies. In addition, There is a growing concern that introducing foreign genes into food plants may have an unexpected and negative impact on human health. On the whole, with the exception of possible allergenicity, scientists believe that GM foods do not present a risk to human health.

http://www.csa.com/discoveryguides/gmfood/overview.php

http://en.wikipedia.org/wiki/Genetically_modified_food_controversies

http://www.consumersinternational.org/Shared_ASP_Files/UploadedFiles/7E77E1CE-0F09-43D6-8B48-714EC01ACA55_Bologna-logo-l56x200.gif

Principles of Genetic Modification Processes

The term "genetically modified" is applied only to products that have been genetically engineered, where genetic material (deoxyribonucleic acid or DNA) has been manipulated or where genes from one organism (animal, plant species or microorganism) have been transferred to the genetic material of another. With recombinant DNA technology, DNA molecules from different sources are combined in vitro into one molecule to create a new gene. This DNA is then transferred into an organism and causes the expression of modified or novel traits. The general principle of producing a GMO is to introduce new genetic material into an organism's genome to generate new traits.
One example of the use of these techniques in the health field is the development of genetically engineered bacteria containing a human gene that can produce the insulin needed to treat diabetics. Food products derived from genetic engineering are primarily in the plant world. In Canada, 42 genetically modified plants have been approved for human consumption; they include certain varieties of canola, tomatoes, potatoes, corn, soya, flax, cotton and squash. These plants are used in a range of food products; for instance, soya is used in processed products such as chocolate, baby food and cake mixes. Transgenic animals have been produced for research purposes or for manufacturing pharmaceutical products but, for the moment, these have not entered the food chain.

http://en.wikipedia.org/wiki/Genetically_modified_organism

http://biotech.about.com/od/faq/f/GMOs.htm
http://dsp-psd.tpsgc.gc.ca/Collection-R/LoPBdP/BP/prb9912-e.htm

http://www.itmonline.org/arts/gmo.htm

My Appraisement for Food Safety Course

There have been nearly two months since I took the course--Food safety. It mainly contains two contents, HACCP and GM food. HACCP is an acronym for "hazard analysis critical control point" and can be used to ensure the food safety during the processing, selling and purchasing of food and ingredients.
I learnt about it in some course in Nanchang University, but didn't still study it comprehensively. So I am eager to learn it. But to my surprise, the method of delivering is so different from that in China. There aren't teachers standing the classroom to deliver the lessens. And all discussion and tasks are done in the blackboard online. The students must learn new knowledge and research project by themselves using the source in library or online.
In my opinion, the school provide a very useful and efficient platform--blackboard for all students. The efficient discussion can be conducted even the students never meet. In addition, to some extent, the method of delivering could let student own the ability of learning and researching by themselves. And the teamwork can make students realise the importance of cooperation. Lastly, the tasks are based on the practical background, so it is natural to make the students learn the practical ability.
But there are also some problems occuring during the process. Firstly, the interchange between the students and teachers are not enough, which make the students' efficiency not high. Secondly, when we all pay attention to how to solve the task, we may ignor the master of HACCP theroy or cannot establish our integrated konwledge frame.
There is still a project to solve. I think we can do better than before.