15. Labelling issues

In the UK, labelling issues are addressed by the Food Advisory Committee (FAC). this committee published a set of guidelines for determining whether a food containing material from a GMO should be labelled.

the provisions for labelling in the new European Regulations are as follows:

1. specific labelling requirements shall apply to ensure that the consumer is informed of:

• any characteristics or food property, such as composition, nutritional value or nutritional effects, or intended use of food, which renders a novel food or food ingredient significantly different from an existing food or food ingredient. in such a case, the labelling must mention the characteristics or properties modified, accompanied by a method by which that characteristic or property was obtained;
• the presence in the novel food or food ingredient of material which is not present in an existing equivalent foodstuff, and which may have implications for the health of certain sections of the populations
• the presence in the novel food or food ingredient of material which is not present in an existing equivalent foodstuff and which may give rise to ethical concerns.
• the presence in the food or food ingredient of a genetically modified organism within the meaning of Directive 90/220/EEC if, according to a committee (European Standing Committee on Foodstuffs) decision under Article 13, it does not corresspond solely to modification of its agricultural characteristics.

2. in the absence of existing equivalent food or food ingredient, appropriate provisions shall be adopted where neccessary in order to ensure that consumers are adequately informed of the nature of the food or food ingredient.

Reference:

Institute of Food Science and Technology (UK). Labelling issues. Guide to Food Technology. Year 1996. Chapter 9.Pages 51,52.

14. Myotoxin Contamination

Mycotoxin contamination

Asperigillus Flavus and Fusarium spp. produce potent myocotoxin (aflatoxins and tricothecenes respectively). government throughout the world have established allowable limits for several mycotoxins in food.

U.S Food And Drug Administration (FDA) allows 20 micrograms/kg(ppb) contamination of aflatoxins in food (aimed at nuts and nut products). allowable levels for feed are higher (e.g. 300 ppb).

Most mycotoxin detection is done through antibody based tests or analytical chemical techniques (e.g. high performance liquid chromatography [HPLC])

Reference:
Johnson.P. Department of Biology Acadia University. Introduction to Food Technology. Year 2002. Chapter 6, Diagnostic Systems. Page 156.

13. Diagnostics for saftey and authenication of foods.

Bioluminescence
the use of this method has necesitated the development of specific clean up procedures for removing non microbial ATP from foods. it also can be engineered into bacterial genomes and luminescence used as a measure of biological activity in the presence of environment toxins.

Enzyme Based Assays and immunodiagnostics
sensitivity, specificity and simplicity have been improved by conjugating enzymes with specific antibody giving rise to Enzyme Linked Immunosorbent Assay(ELISA).

In food microbiology, ELISAs have a greater impact. Pathogens including Salmonella, Listeria and Escherichia Coli and the bacterial toxins from Staphylococcus Aureus, Bacillus Cereus and Clostridium Botulinum can now be detected using commericial kits. Furthurmore, ELISA kits are able to detect fungal toxins such as aflatoxin and ochratoxin. It is also used to detect Clostridium Botulinum enterotoxins and certain molds (e.g. Asperigiullus and Penicillium spp.)

DNA Probes
Gene probes are specific. Simple methods based on nucleic acid probes are developed for detecting specific genes expressing gungal toxins. they also have potential in authenicity testing. however, a problem is faced as most DNA probes can only detect approximately 10^5 cells/ml in a food matrix.and many pathogenic microorganisms that may be present at very low levels need to be enriched using conventional cultural methods. this problem can be solved as nanogram quantities of DNA can be amplified using the polymerase chain reaction (PCR) and is able to detect Legionella at a levele of 100 cells/ml in 4h. Similar developments were developed to detect Salmonella. therefore, gene probes are constructed to contain complementary bases which hydrise target DNA sequences.

Biosensors
Most diagnostic involve the specific binding of target molecule to a recognition molecule. binding event is sensed by labelling the ligated complex. optical biosensors are developed for the estimation of biotin and folate and for the detection of Salmonella and Listeria.

Reference:
Institute of Food Science and Technology (UK). Diagnostics for saftey and authenication of foods. Guide to Food Technology. Year 1996. Pages 41-45.

12. Various common food toxins and toxicity

I found the various common food toxins, pathogens and its toxicity.

In food, the common foodborne pathogens are Bacillus Cereus, Clostridium Botulinum, Esherichia Coli, Listeria Monocytogenes, Salmonella, Staphylococcus Aureus, and Asperigillus Flavus.

Peanut butter which is produced by the company contains foodborne pathogens such as Salmonella, Aspergillus Flavus, Staphylococcus Aureus, Rhizopus and Clostridium Botulinum. It also contains mycotoxins such as Aflatoxin which is produced by Asperigillus Flavus.

Bacillus Cereus
- cause Bacillus Cereus Food poisoning and it produces a diarrhoeal enterotoxin.
-sources: milk, dairy products.
- can be identified by the isolation and enumeration of B.cereus, preferably in both the infected food and the faeces of the victims.
- Procedures for isolation and enumeration of B.cereus involve direct agar plating techniques. However methods for detecting B.cereus enterotoxins are neither highly specific nor quantitative.
- Optimum temperature range for this emetic toxin production is 25 to 30 C. the emetic toxin is heat stable and can withstand normal cooking temperatures. So food is to be cooled rapidly to a temperature that prevents the growth of B.Cereus and food to be held in a warm state should be maintained above 60C.

Clostridium Botulinum
- can cause food borne botulism and produces C.botulinum toxin.
- Sources: may occur in almost all food, vegetable or animal origin.
- No microbiology methods are specifically designed for C.botulinum. Methods of enumerating the clostridia usually rely on reduction of sulphite to sulphide with the formation of black colonies which demonstrates the presence of C.botulinum by enrichment culture and toxin tests.

Escherichia Coli
- can cause infection and food borne illness.
- Sources: Milk, meat.
- Isolation of pathogenic E.coli involves plating sample on MacConkey or eosin-methylene blue agar.
- Enrichment and selective procedures would be carried out after black colonies are picked and identified as E.coli.
- Detection for E.coli is facilitated by enrichment and electromagnetic separation. Several biochemical tests are done to identify E.coli and some examples are Gram’s stain positive, indole positive, mannitol-positive, and Voges-Proskauer-negative. Important measures are taken to prevent food poisioning by education food workers in safe food handling techniques and proper personal hygiene.

Listeria Monocytogenes
- can cause listeriosis.
- sources: raw meat, wet sirfaces in food processing plants.
- an opportunistic pathogen that is capable of surving and multiplying in simple nutrient media and outside animal hosts.
- able to grow in simple bacteriological media. It is able to grow at low temperatures and thus multiply.
- Isolation can be done after plating onto non selective media such as blood soy agar and selective media such as modified McBride’s agar. Several enzyme-linked immunosorbent assay (ELISA) methods and nucleic acid probes are available for identification purposes.
- Listeriosis can be reduced whereby HACCP should be applied from farm to consumers to minimize the risk of food borne illnesses.

Salmonella
- can cause gastroenteritis, enteric fever and bacteraemia, focal infections and sequelae.
- sources: food of animal origin.
- Detection of salmonella involves pre-enrichment, enrichment, selective differential plating, isolation and identification.
- enumerated by the most probable number technique though it is a cumbersome procedure and too expensive for use in large number of samples.
- Identification of Salmonella can be done by primary screening on non selective differential agars such as triple sugar iron (TSI), and further identification can be done by biochemical testing of pure cultures. With the use of heat, irradiation, acidification and combinations of factors are used to destroy salmonella in food since low numbers of salmonellae can cause illness.

Staphylococcus Aureus
- can cause staphylococcal food poisoning.
- Sources: mucous membrane, and skin of all food animals.
- method of enumeration is Baird Parker’s medium.
- procedure for detecting staphylococcal enterotoxin in food is a combination of extraction, concentration and final detection of the toxin by the use of enzyme-linked immunosorbent assay (ELISA).
- Control can be achieved by preventing products from contamination and avoiding conditions where growth may occur.

Asperigillus
- produces mycotoxins and can cause mycotoxin poisoning.
- sources: peanut, corn, cottonseed.
- Enumeration of Asperigillus flavus can be done on antibacterial enumeration medium that contains inhibitors to reduce colony spreading.
- Identification of Asperigillus flavus grow rapidly on standard identification media such as malt extract agar. Asperigillus also produces mycotoxins such as aflatoxins which are found to be acute and chronically toxic in both animals and in man.
- ELISA techniques are used for toxin estimation and controlling of aflatoxin in corn can be directly detected when they fluoresce under UV light.


Reference:
Blackie Academic & Professional. Microorganisms In Foods 5. Microbiological specifications of food pathogens. 1996

p.s: book found in school library.

11. When to label food as Genetically Modified?

Found an useful decision tree in the FoodSafety.gov.au website which i think might be useful.
Reference:

http://www.foodstandards.gov.au/_srcfiles/user_guide_GM_labelling_0817.pdf (accessed: 16 June 2008)

10. How to distinguish GM food from natural food?

In the learning issues in our HFLA template, i was to research on ways to distinguish GM food from natural food and these were what i have found.

To distinguish GM food from natural food, it is important to check the presence of marker genes and promoter genes as these genes are using in the process of transformation.
Marker genes are used to quantify gene expression and to ensure that the DNA is properly delivered and transformation is stable. However, for plant cell transformation, marker genes can only be expressed inside cells of the target tissue and not in any contaminating microorganisms.
Also, Promoter genes are used in the process of transformation as it starts the mechanism of the DNA chain and cooperates with marker genes.


Reference:
Genes needed for transformation. http://library.thinkquest.org/C004033F/gmprocess_genes.htm (accessed: 14 June 2008)

9. Advantages and Disadvantages of GM food

Found some information on the advantages and disadvantages on GM food as well.

Advantages:

1. Increase the crop yields to feed the world population
2. Increase the tolerance of crops to adverse growing conditions, e.g. drought
3. improve the nutrient composition of crops, e.g. increase the protein content of rice.
4. Provide resistance to crop pests and reduce the use of pesticides by growing GM food such as Bt corn, i.e. save the environment
5. Improve sensory attributes of food, e.g. flavor, texture
6. Improve the processing characteristics so as to reduce wastage of food and minimize the cost during transport and storage
7. Eliminate allergy-causing properties in some foods
8. herbicide tolerance. Crop plants genetically-engineered to be resistant to one powerful herbicide could help prevent environmental damage by reducing the amount of herbicides needed. For example, Monsanto's strain of soybeans.
9. Disease resistance.
10. Pharmaceuticals. Medicines and vaccines are costly to produce and sometimes require special storage conditions not readily available in third world countries. Researchers are working to develop edible vaccines in tomatoes and potatoes

Disadvantages:

1. Unintended modification of similar species in the neighboring fields due to cross pollination
2. Disturbing the balance of ecosystems, e.g. some animals may lose their home when extending farmland area
3. A chance of developing super pests as DNA is changed
4. The initial genetic structure of both animals and plants will be disturbed
5. Vegetarians may worry about eating plants which contains genes from animals for religious, health or other reasons
6. Unintended harm to other organisms. pollen from B.t. corn caused high mortality rates in monarch butterfly caterpillars. Unfortunately, B.t. toxins kill many species of insect larvae indiscriminately; it is not possible to design a B.t. toxin that would only kill crop-damaging pests and remain harmless to all other insects.
7. Reduced effectiveness of pesticides. there are concerns that insects will become resistant to B.t. or other crops that have been genetically-modified to produce their own pesticides.
8. Allergenicity (Human health risk) There is a possibility that introducing a gene into a plant may create a new allergen or cause an allergic reaction in individuals. testing of GM foods may be required to avoid the possibility of harm to consumers with food allergies. Labeling of GM foods and food products plays an important role.
9. Economic concerns. Bringing a GM food to market is a lengthy and costly process. Many new plant genetic engineering technologies and GM plants have been patented Yet consumer advocates are worried that patenting these new plant varieties will raise the price of seeds so high that small farmers and third world countries will not be able to afford seeds for GM crops, thus widening the gap between the wealthy and the poor.

Reference:

GM Food. http://library.thinkquest.org/C004033F/pros&cons_text.htm (accessed: 14 June 2008)

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