Sunday, July 22, 2007

How are GMOs developed?

GMO stands for Genetically Modified Organism

The steps involved in developing genetically modified organism are shown below:

  1. Identify a particlar characteristic from any organism (e.g. a plant, animal or microorganism) and work out which gene or genes in the organism are responsible for producing that characterisitc. E.g. the desired characterisitc and the gene that produces this characteristics has been identified in a microorganism (a bacterium). This is the gene of interest.
  2. Use the techiniques of moleculare biology to isolate and copy the required gene. If the gene of interest was found in a bacterium it will have an 'on switch' (and other switches) that function only in bacterial cells. For a gene to function in a different type of cell (for example, in a plant cell), the bacterial switches need to be removed and different switches added to the gene to allow it to function in a plant cell. These switches in all plant cells or in spcific plant tissues (e.g. in root tissue only), so that the new trait will only be switched on in the roots.
  3. When developing a GMO, add appropriate gene switches to the gene of interest, to allow it to function in the cells of the recipient organism.
  4. The gene of interst, together with its gene switches, is inserted into the cells of the host organism, again using molecular biology techniques. Cell with the new gene inserted into their genome are referd to as 'transformed' cells. They contain all the usual genes of the recipient organism as well as the new gene or genes with which they have been transformed.
  5. Grow transformed cells into whole plants in the laboratory; this is done using selective nutrient-rich media. The plants are examined to ensure that they have the desired physical characteristic conferred by the new gene.
  6. Genetically modified plants are bred with conventional plants of the same variety to roduce seed for further tesing and possibly for further commercial use. The entire process from the initial gene selection to commercial producion can take up to 10 years or more.

Basis for approval of GM foods

Basis for approval of GM foods (The safety assessment process)

FSANZ prepares a detailed report on the safety assessment of each new GM food, covering all the points outlined below. Ingeneral, a GM food is considered safe for human consumption if FSANZ is satisfied of the following:

All new genetic material has been examined in detail.
  • Where did the new genetic material come from, what is its function, how was it put into the GM food and how is it arranged within the genetic material of the plant or animal?

The new genetic material stays the same and is passed on in a predictable way from generation to generation.

  • Is the new genetic material stably intergrated within the DNA of the GM organism?
  • Is the novel trait expressed consistently over a number of generation?

All new proteins have been examined in detail.

  • Where and when re the new proteins found in the plant or animal?
  • Do they have the expected size, structure and biological activity?

The new proteins are unlikely to be toxic or allergenic.

  • Do the new proteins come from living organisms that contain no major toxins or allergens ?
  • Are the new proteins dissimilar to known toxins and allergens?
  • Do the new proteins lack other physical and biochemical characteristics typical of toxins and allergens?

The new proteins do not cause any detectable toxicity in animal studies.

  • When the purified new proteins are given in large doses to rats or mice, are there any adverse effects?

The potential transfer of new genetic material to bacterial cells in the human digestive tract will not have a significant impact on human health.

  • Are antbiotic resistance genes present? Is the corresponding anitbiotic used in human or veterinary medicine?
  • What would be the health impact if the new genes were to be transferred to bacteria in the human gut?

The composition of the food, including naturally occuring toxins, allergens and antinutrients, is not significant altered compared to the non GM food.

  • Is the composition of the food (for example, the proteins, fat, fibre, carbohydrate, amino acids, vitamins, minerals, moisture content, and other biologically acitve molecules) substainlly different from that of the conventional food?
  • If so, does the difference found in the GM food affect the safety of the food, and will it make the food less nutritious or healthy?

Regulation and labelling of GM foods

According to Australia New Zealand Food Standards Code
  • Prohibits the use of additives, processing aids and nutritive substances in food unless there is a specific permission for these substances following a safety asssessment.
  • Prohibits the use of novel foods, irradiated foods and foods produced using gene technology unless there is a specific permission for these foods following a safety assessment.
  • Specifies maximum limits for contaminants and natural toxicants in food
  • Establishes microbiological and processing requirements for food
  • Specifies the composition and labelling requirements for many commodities.

According to Standard 1.5.2-Food Produced Using Gene Technology, of the Australia New Zealand Food Standards Code regulates food derived from GM plants, animals or microorganisms. - It does not apply to GM food additives or processing aids, which already overed by other food standards.

Any GM foods (or ingredients derived from them) that are listed in Standard 1.5.2 have passed the safety assessment and approval process, and can therefore be sold in Australia and New Zealand, and used to make other foods.

Safety assessments of GM foods

Under Standard 1.5.2, GM foods must be assessed for safety, and only those found to be safe are approved for sale. FSANZ is responsible for carrying our safety assessments of GM foods on behalf of the Australian Government, the state and territory governments of Australia, and the Government of New Zealand. In doing so, FSANZ takes a cautious approach because, even though most GM foods are derived from foods with a long-established history of safe human consumption (such as corn and soybean), the GM versions are new to the diet.

Labelling of GM foods

Standard 1.5.2 also contains provisions for the labelling of GM foods-these provisions have been in effect since December 2001. The safety of a GM food is assessed before it can be sold as food: therefore, the purpose of labelling is simply to provide information to consumers, allowing them to purchase or avoid GM foods depending on their own views and beliefs. The GM food labelling regulations, which are among the most stringent in the world, represent a balance between the needs of consumers and what governments can realistically enforce.

Under Standard 1.5.2, if a food, food ingredient, additive or processing aid contains novel DNA or protein that has come from an approved GM food, it must be labelled with the words 'genetically modified'. Labelling regulation also cover GM foods that differ in composition to the conventional counterpart; in this case, he labelling must make claer to consmers the altered characteristics of the food.

There are some exemptions to the labelling requirements for GM foods. Foods that do not need to be labelled as 'genetically modified' include highly refined foods that contain no DNA or protein (for example, oil made from GM soy beans), and foods in which GM ingredients are present accidentally and make up lessthan 1% of the final food.

Role of other agencies

In Australia and New Zealand, FSANZ is not the only government agency involved with the regulation of GM microorganisms, plants, and animals and their products. As shown in Table 2.1, the responsibilities of other agencies cover broader issue than food safety, such as the environment, quarantine and the registraion of agricultural chemicals. Where products require the approval of several agencies, the agencies coordinate with one another.

Concerns of GM foods

Concerns of people with regards to GM foods

Other frequently asked questions would be ‘what if I eat DNA in GM food?’, ‘How about allergens and toxins in GM foods?’, ‘Concerns of antibiotic resistance genes in GM foods’ and ‘What about herbicides and pesticides residues in GM foods?’. Firstly, we eat DNA from our everyday food which will be broken down in the digestive system into building blocks and can be metabolized by body cells. Eating DNA from GM or conventional foods will not change our own DNA or that of our children. Secondly, certain proteins in food can cause unusual immune reaction are known as allergens. If conventional foods contain allergens, GM foods similarly contain the same allergens. But food monitoring bodies will check to ensure the level of these naturally occurring allergens in GM foods does not increased significantly and new proteins found in GM foods are not allergenic. Same for toxin, toxic substances that are naturally present in many conventional foods can also is found in GM foods. Thus, government bodies would compare the usual amount of these naturally-occurring toxins that are found in the conventional with the GM foods to ensure that the toxins level consumed are not harmful to health. New protein in GM food is also check if it is toxic, if it is toxic and may cause adverse health effects at levels of expected dietary intake, it would not be approved for sale. Thirdly, the worries of people about consuming antibiotic resistance genes in GM foods is it could transfer to disease-causing bacteria in human digestive tract and could results in infections that are resistant to treatment with antibiotics. But antibiotic resistance genes that are currently present in GM foods are not widely used in human medicine because resistance to them is already widespread. Lastly, all foods sold must comply with relevant maximum residue limits, whether the foods have been genetically modified or not. Thus, even if herbicide or pesticide used changes because crops have been modified to tolerate these chemicals, they will not contain unsafe levels of residues. In some cases, level of these chemicals used on GM crops might be reduced.

Tuesday, July 17, 2007

Controversial issues about GM foods (part 2)

Support of Genetic Engineering

1. Ethical and moral isues:
Scientists throughout history have been persecuted and even put to death by fearful people who accuse them of playing God. Yet, today many of the world's citizens enjoy a long and healthy life of comfort and convenience due to once0feared scientific advances put to practical use.

2. Advanced technology:
Recombinant DNA technology is precise and reliable. Many of the most exciting recent advances in medicine, agriculture, and technology were made possible by the application of this technology.

3. Environmental protection:
Genetic engineering may be the only hope of saving rain forest and other habitats from destruction. Through genetic engineering, farmers can make use of previously unproductive lands such as salt-rich soils and arid areas.

4. Genetic improvements:
Genetic side effects are more likely to benefit the environment than to harm it.

5. Improved crop resistance:
Pests and diseases can be specifically fought on a case-by-case basis. Biotechnology is the key to defense.

6. Gene pool reserved:
Thanks to advances in genetics, laboratories around the world are able to stockpile the genetic material of millions of species that, without such advances, would have been lost forever.

7. Everyone profits:
Industries benefit from genetic engineering, and a thiving food industry benefits the nation and it people, as witnessed by countries lacking such industries. Genetic engineering promises to provide adequate nutritious food for millions who lack such food today. Developed nations gain cheaper, more attractive, more delicious fods with greater variety and availability year round.

8. Safe for people:
Human safety testing of genetically altered foodstuff are known, and foods likely to contain them are clearly labeled to warn consumers.

9. Control of allergens:
A few allergens can be transferred into foods, but these are known, and foods likely to contain them are clearly labeled to warn consumers.

10. Increased nutrients:
Genetic modifications can easily enhance the nutrients in foods.

11. Excellent product tracking:
The identity and location of genetically altered fodstuffs are known, and they can be tracked should problems arise.

12. Conservative use of herbicides:
Farmers will not waste expensive berbicides in second or third applications when the precribled amount gets the job done the first time.

13. Reduced pesicides on foods:
Pesticides produced by produce in tiny amounts known to be safe for consumption are more predictable than applications by agricultural workers who make mistakes. Becasue other genetic manipulations will eliminate the need for postharvest spraying, fewer pesticides will reach the dinner table.

14. Sufficient regulation and rapid response:
Government agencies are efficient in identifying and correcting problems as they occur in the industry.

Controversial issues of GM Foods (part 1)

Opposition to Genetic Engineering

1. Ethical and moral issues:
It is immoral to 'play God' by mixing genes from organisms unable to do so naturally. Religious and vegetarian groups object to genes from prohibited species occurring in their allowable foods.

2. Imperfect Technology:
The technlogy is young and imperfect- genes rarely function in just one way, their placement is imprecise ('shotgun'), and all of their potential effects are impossible to predict. Toxins are likely to be produced as the desired triat. Over 95% of DNA is called "junk"because scientists have not yet determined its function.

3. Evironmental concerns:
Environmental side effects are unknown. The power of a genetically modified organism to change the world's environments is unknown until such changes actually occur - then the 'genie is out of the bottle'. Once out, the genie cannot be put back in the bottle becasue insects, birds, and the wind distribute genetically altered seed and pollen to points unknown.

4. Genetic pollution:
Other kinds of pollution can often be cleaned up with money time, and effort. Once genes are spliced into living things, those genes forever bear the imprint of human tampering.

5. Crop Vulnerability:
Pests and disease can quickly adapt to overtake genetically idntical plants or animalsaround the world. Diversity is key to defense.

6. Loss of gene pool:
Loss of geneticdiversity threatens to deplete valuable gene banks from which scientists can develop new agricultural crops.

7. Profit motive:
Genetic engineering will profit industry more than the world's poor and hungry.

8. Unproven safety for people:
Human safety testing of genetically altered products is generally lacking. The pollulation is an unwitting experimental group in a nationwide laboratory study for the benefit of industry.

9. Increased allergens:
Allergens can unwittly be transfered into foods.

10. Decreased nutrients:
A fresh-loking tomato or other produce held for several weeks may have lost substanial nutrients.

11. No product tracking:
Without labelling, the food industry cannot track problems to the source.

12. Overuse of herbicides:
Farmers, knowing that their crops resists herbicide effects, will use them liberally.

13. Increased consumption of pesticides:
When a pesticide is produced by the flesh of produce, consumers cannot wash it off the skin of the produce with running water as they can with ordinary sprays.

14. Lack of oversight:
Government oversight is run by industry people for the benefit of industry- no one is watching out for the consumer.

Sunday, May 27, 2007

Info on some common bacteria

Campylobacter jejuni
Incubation period: 2-5 days
Signs and Symptoms: Diarrhea, cramps, fever, muscle pain, nausea and vomiting
Associated Foods: Undercooked or raw poultry and beef, unpasteurized milk and dairy products, and contminated water.
Duration of Illness: 2-10 days

Clostridium botlinum (toxin-producing)
Incubation period: 3-30 days
Signs and Symptoms: Lethargy, weakness, poor feeding, constipation, poor head control, poor gag and suck, poor muscle tone
Associated Foods: Honey, home-canned fruits and vegetables.
Duration of Illness: Variable

Clostridinum perferingens
Incubation period: 8-16 hours
Signs and Symptoms: Watery diarrhea, nausea, abdominal cramps
Associated Foods: Meats, poultry, gravy, dried or precooked foods and beans.
Duration of Illness: 1-2 days

E.coli (toxin-producing)
Incubation period: 1-8 days
Signs and Symptoms: Severe diarrhea(often bloody), abdominal pain and vomiting
Associated Foods:Undercooked beef, unpasteurized milk and juice, raw fruits and vegetables, salami, salad dresing, imported cheese, and conaminated water.
Duration of Illness: 5-10 days

Listeria monocytogenes
Incubation period: 9-48 hours for gastrointestinal symptoms
Signs and Symptoms: Fever, muscle aches, and nausea or diarrhea
Associated Foods: Fresh soft cheeses, unpasteurized milk and cheese, ice cream, raw vegetables, raw and cooked poultry, raw meat and fish, ready-to-eat deli meat and hotdogs.
Duration of Illness: Variable

Salmonella
Incubation period: 1-3 days
Signs and Symptoms: Diarrhea, fever, abdominal, cramps, vomiting, headache, constipation, chills and muscle pain
Associated Foods: Contaminated eggs, poultry, unpasteurized milk and juice, cheese, raw meat and fish, and shrimp, yeast, coconut, salad dressing, cake mixes, cream-filled desserts, peanuts butter, cocoa, chocolate, and raw fruits and vegetables.
Duration of Illness: 4-7 days

Shigella
Incubation period: 1-2 days
Signs and Symptoms: Abdominal cramps, fever, nausea, vomiting,chills, fatigue, and diarrhea
Associated Foods: Food or water contaminated with fecal material, raw vegetables, egg salad
Duration of Illness: 4-7 days

Staphylococcus aureus (toxin-producing)
Incubation period:
Signs and Symptoms: Sudden onset od severe nausea and vomiting, exhaustion, and abdominal cramps. Diarrhea and fever may be present.
Associated Foods: Improperly refrigerated meats, poultry, eggs, potato salad, egg salad and cream pastries
Duration of Illness: 1-2 days

Spoilage of cooked poultry products

Microbiological content of cooked products are affected by the method of processing, packaging and storage. (Denton and Gardner, 1982; Tompkin, 1986; Johnston and Tompkin, 1992). All the products in this catergory should be cooked at a time and temperature to obtain a cooked appearance, appropriate tenderness, and other desirable organoleptic qualities. In addition, the processes should also be adequate to destroy enteric pathogens like Salmonellae, C. jejuni, L. monocytogenes and Staph. aureus which normaly found in raw poultry.
Vegetative bacteria and some spores on the surface of the poultry products are killed during cooking, but some like enterococci, Lactobacillus viridescens in the center of the product may survive depending on the thermal process. Thermal processes are not adequate to ensure the destruction of spore-forming pathogens like CL. perfringens and CL. botulinum. Cooked products are subject to post-process contamination during slicing and packaging.
When chicken is subjected to frying in oil, temperature at the geometric center usually reach 93ºC or higher, which is lethal to vegetative bacteria but not to spores. These products are also subjected to post-process contamination during subsequent handling and packaging.
Common microogranisms that are involved in cooked poultry can be classified into 2 groups: 1) Enteric pathogens and Staph. aureus that are present in raw poultry and which could contaminate the products after cooking; 2) Psychrotrophic pathogens which can establish themselves in the cooked product environment e.g. L. monocytogenes.
Other possible pathogens arre like CL. botulinum, CL. perfringens and B.cereus which are spore-forming which can survive during the cooking of the perishable poultry products.
To ensure the microbiological safety and quality of the cooked poultry products , HACCP are used. The HACCPs used are:
  1. To ensure the use of a thermal process that destroys non-spore-forming pathogens
  2. Control the chiling step to prevent the multipication of mesophilic spore-forming pathogens
  3. Prevent cross-contamination from raw meats to cooked product
  4. Control the environment and handling of cooked products to minimize contamination with L.monocytogenes
  5. Control storage and distribution times and temp. which will ensure microbiological safety
  6. Provide food hadling and preparation procedurs to the end users.

Spoilage of frozen chicken product

Frozen poultry products do not usually undergo microbial spoilage. Maybe some yeasts and molds can grow on frozen meaat at temp. as low as -7ºC. Cadosporium herbaum ( causing black spots); Thamnidium elegans ( causing whisker-like growth); and Sporotrichum carnis ( causing white spots).
Spoilage of frozen poultry products usually occurs during thawing or stored at refrigerated temperature from sufficient time. The water that released from thawing is hazardous as it may contain pathogen like Campylobacter jejuni and Clostridium perfringens.
Enzymatic activity can cause off-flavour in frozen poultry products that are stored for prolonged periods. The extent of product deterioration will vary with the type of product, method of processing and packaging, and storage conditions.
To ensure the standard of microbiology and safety of frozen poultry products. Chilled carcasses must be packaged , promptly frozen, and held at or near -18ºC. Carcasses must be thawed in a manner that decomposition is limited and growth of microbial is prevented. * Both thawing poultry and thawing water should be prevented from contacting ready-to-eat foods.

Saturday, May 12, 2007

Process flow of chicken

Chicken--->Slaughter--->Scalding--->Defeathering--->Evisceration--->Spray-washing
--->Chilling--->Packaging--->Freezing--->Delivery to hospital--->Storing at hospital's walk-in-freezer


  1. Slaughter: Birds are stunnd by electrical shock then cut their necks to sever carotid arteries. This step does not have any significant impact on the microbial qulity of finished product.
  2. Scalding: To facilitate the removal of feathers.During scalding, soil,dust and fecal matter from the feet,feathers, skin, intestinal tract and respiration tract are released into the scald water.Thus, a variety of bacteria like Clostridium, Micrococcuc, Proteus, Pseudomonas, Salmonella, Staphylococcus and Streptococcus can be isolated from the scald water. However, the aerobic plate counts of scald water could be mainain at least <50>
  3. Defeathering: Involved a series of machines through which scalded chickens will pass and in which rotating rubber finger beat the loosen feathers from the carcass. The aerobic plate count and Staphylococcal counts are higher in this process due to insufficient cleaning of the rubber fingers. Rubber fingers are difficlt to clean and are subject to wearing and cracking. Even before they deteriorate, the microorganisms can readily penetrate below the surface of the rubber.The freshly scalded chickes also create a warm and moist operating temperature within the defeathering machines thus provide a more favourable conditions for Staph.aureus to grow.The defeathering machines can be also colonized by some strains of Staph.aureus which will produce an extracellular slime and a tendency toward clumping. When these properties forms, they are more likely to increase the resistance of these strains to low level of chlorine and become indigenous to equipment as time goes by. Hence, there will be a mix strains of Staph.aureus from the chicken and the equipment. All these can be partially controlled by emphasizing adequate cleaing before disinfecting, replacing orn fingers, avoid excessive feathers accummulation, providing a spray of water with sufficient chlorine and not shrouding the machine so heat can escape. During defeathering, the major contamination are Campylobacter spp., Salmonellae and E.coli. It tends to spread microorganisms from contaminate carcasses to many carcasses. The microbial population on the carcasses will directly reflects the microbial quality of the carasses immediately after defeathering.
  4. Evisceration: Edible viscera like hearts,livers and gizzards are removed from the carcassess. Thus, microorganisms are transferred from carcass to carcass by workers,inspectors and equipment. Besides, manual opening the abdominal cavity and evisceration can give rise to considerable contamination esp. To prevent an increase in microbial counts on the carcasses, mechanical evisceration requires proper maintenance and continuous cleaning of machinery.
  5. Spray-washing: It is conducted after defeathering and again after evisceration to remove organic materials and some microorganisms acquired during evisceration. The sprays help to decrease the aerobic plate count, Enterobacteriaceae and coliforms by 50 to 90%. Adding cholrine to spray water can help to reduce bacterial counts. However, certain Pseudomonas spp. can still contaminate teh carcasses.
  6. Chilling: This process is necessary to delay the growth of psychrotrophic spoilage bacteria and prevent growth of most foodborne bacteria thus improve the microbial safety and quality.
  7. Packaging: The hygienic conditions of the conveyors and other equipments like knives and tables which contact the chilled chicken are the major factor influencing the rate of spoilage during packaging.
  8. Freezing: The main purpose of this process is to extend the shelf-life of the carcasses by inhibiting the growth of those pathogenic mesophiles.
  9. Delivery: During transportation , the temperature of food maintain <>Storage Condition @ hospital: The delivered carcasses are stored in a walk-in-freezer at tepmerature of -18 degree celsius to inhibit the growth of most pathogenic microorganisms.

Saturday, May 5, 2007

Recipe

Stew chicken with fragrant rice(70-75pax)

Ingredients:

Marinade for chicken
8kg Lean chicken meat,diced
6tbsp Sesame oil
3tbsp White pepper
150g Motorcar flour

Fragrant rice
7kg Uncooked rice
7kg Water,boiled
2/3bowl Fragrant oil
1/3bowl Sesame oil

*P.S: 1bowl=400ml

Other ingredients
5L Chicken stock
150ml Soya bean oil
300ml Dark soya sauce
350ml Motorcar flour (Mixed with water)
100g Ginger,sliced
90g Brown onion,sliced

Preparation:
  1. Combine all the ingredients required for the marination of chicken in a mixing bowl.
  2. Mix well the marinade on the chicken meat.
  3. Marinate overnight.

Method:

  1. First add boiled water into the rice cooker .
  2. Then add the uncooked rice into the cooker.
  3. Let it cook for 40mins.
  4. When the rice is cooked, add fragrant oil and sesame oil into it.
  5. Mix the oils and rice well.
  6. Saute the marinated chicken meat.
  7. Add oil into heated wok.
  8. Saute the ginger first in the wok.
  9. Add the onions into the wok and saute until slightly golden brown.
  10. Add dark soya sauce into the wok.
  11. Then stir-fry the chicken for 5mins and add chicken stock into the wok.
  12. Simmer until it boils.
  13. Thicken the stew chicken's gravy with motorcar flour.
  14. Dish it up and it is ready to be serve.

Sunday, April 15, 2007

food safety

Definition of Food Safety:

Food Safety refers to the conditions and practices that preserve the quality of food to prevent contamination and food-borne illnesses.

Why is Food Safety important?

Because foodborne illness will take place if food safety measurements are not taken into consideration, which will adversely affects the health of human who consumed it. Foodborne illness is the sickness that som people experience when they eat contaminated food. Not only it can caused harm to the thealth of human beings but also has a major economic impact. It cost our society billions of dollars each year. This costs included medical expenses, lost workand reduced productivity by victims of the illness, legal fees,punitive damages, increased insurance premiums, lost business, and loss of reputation.

Important elements of Food Safety:

1. Time
2. Temperature
3. Good Sanitation
4. Good Hygiene

Sources of food contamination :

  • Air
  • Water
  • Soil
  • Food handlers
  • Packaging materials
  • Animals,rodents & insects
  • Food contact surfaces
  • Ingredients

food safety

Definition of Food Safety:

Food Safety refers to the conditions and practices that preserve the quality of food to prevent contamination and food-borne illnesses.

Why is Food Safety important?

Because foodborne illness will take place if food safety measurements are not taken into consideration, which will adversely affects the health of human who consumed it. Foodborne illness is the sickness that som people experience when they eat contaminated food. Not only it can caused harm to the thealth of human beings but also has a major economic impact. It cost our society billions of dollars each year. This costs included medical expenses, lost workand reduced productivity by victims of the illness, legal fees,punitive damages, increased insurance premiums, lost business, and loss of reputation.

Important elements of Food Safety:

1. Time
2. Temperature
3. Good Sanitation
4. Good Hygiene

Sources of food contamination :

  • Air
  • Water
  • Soil
  • Food handlers
  • Packaging materials
  • Animals,rodents & insects
  • Food contact surfaces
  • Ingredients