Principles of DNA probe

A DNA probe can be developed to identify a specific taxonomic group, by directing the probe to a gene which can be found in all genus and species classified under the same taxonomic group or it can be developed to identify a particular strain of the pathogen, in which the targeted gene can only be specific to this strain.

Firstly, the probes are constructed by preparing pure and specific DNA segments. These probes are inserted into plasmids, the plasmids are transformed, thus increasing the amount of DNA probe. The plasmids are purified and can be used for identification of microorganisms.

A DNA probe is made up nucleic acid molecules, or more specifically, double-stranded DNA. The gene it contains has a known function, thus pieces of single-stranded DNA can be synthesized to compliment it. These are commonly referred to as oligonucleotides. Detection of complementary DNA or RNA targets or made possible with both natural and synthetic oligonucleotides.
DNA strands are held together by hydrogen bonds which can be broken by raising pH above 12 or temperature to above 95°C. As such, the DNA is denatured, producing single-stranded molecules. The hydrogen bonds are reformed between the AT and GC pairs, when the pH and temperature are lowered.

Double-stranded DNA probes must be denatured before the hybridization reaction; while single-stranded oligonucleotide and RNA probes do not. The nucleic acids of the tested samples are denatured via high temperature or high pH, before the labeled gene probe is added. Hydrogen bonds will form between the probe and nucleic acid, if the target nucleic acid in the sample has the same nucleotide sequence as the probe. By rinsing, the unreacted, labeled probe is removed, leaving the probe-target complexes, which is signaled by the bound label.


Principles of Enzyme Immunoassay

Detection of pathogens by enzymes immunoassay (EIA) is based on the interaction of a microbial antigen with its specific antibody and can only be used for substances with immunological properties such as proteins (enzymes), glycoprotein, polysaccharides. As hormones, bacterial antigens and antibodies are made up of protein, enzyme immunoassay is able to detect them. EIA can be used on plasma, serum , urine and cell extracts.

The most common type of testing involves an antibody attached to a solid surface. When placed into the sample, the antibody will latch onto substances it has affinity with, such as antigen and thus forms a bond with it. Another substance which consists of an enzyme linked to a antibody is added into the mixture. The enzymes catalyze the reaction of the antigen-antibody complexes, producing a specific colour. The presence and quantity of the tested substance can be determined by measuring the optical density of the colour.

References:
http://www.cfsan.fda.gov/~ebam/bam-24.html
http://fp.okstate.edu/muriana/foodpath/lect7/6LECT.pdf

Process of genetic modification on plants

There are two main ways:

1) Agrobacteria tumefaciens (a natural soil bacterium that infects plants) is injected into the plant’s cells. The bacteria lodge some of its genes into the plant's genetic material, where the supposed outcome produces damaging tumors. Geneticists extract these tumour-causing genes from the bacteria and replace them with pest resistance or herbicide tolerance genes. The modified bacteria thus transfer the useful genes instead of the disease genes to the plant.

2) A gene gun is used to fire tiny gold particles coated with genes of useful traits directly into a plant's cells.


Types of GM crops

There are two main types:

1) Has the ability to tolerate herbicides that wipe out all other plants. All other plants in the field including weeds will be destroyed. This result in higher yields and reduced herbicide usage compared to conventional crops thus preserves the environment.

2) Has the ability to produce a toxin that kills pests feeding on it.

References:
http://www.guardian.co.uk/theissues/article/0,,969438,00.html
http://www.washingtonpost.com/wp-dyn/content/article/2006/12/06/AR2006120601349.html

Genetic Modification process

Food Recall

USDA RECALL CLASSIFICATIONS
Class I This is a health hazard situation where there is a reasonable probability that the use of the product will cause serious, adverse health consequences or death.
Class II This is a health hazard situation where there is a remote probability of adverse health consequences from the use of the product.
Class III This is a situation where the use of the product will not cause adverse health consequences.


Nutritious Bread Company "Multigrain bread with Chicken filling" recall procedure

1) Recall classification and health risk e.g. CLASS I RECALL HEALTH RISK: HIGH
2) Date of Recall Release e.g. 17 May 2007
3) Recall issued by e.g. Agri-food and Veterinary Authority of Singapore
4) State whether recall is voluntarily made by the company or other organizations (AVA)
5) Gross total of recall products e.g. 1000kg of multigrains sandwich
6) Reason for recall e.g. due to contamination with Salmonella spp.
7) State Production period e.g. 1 May 2007 to 30 May 2007
8) State oulets/ distributors products are distributed to e.g. XYZ Distributor, ABC supermart
9) Urge consumers to return products to point of purchase
10) State how problem was discovered e.g. similar symptoms found in consumers after eating the multigrains sandwiches
11) State and describe products to be recalled e.g. microwavable boxes containing multigrain sandwiches with chicken filling bearing the establishment number "Est 2007Z" and date codes between "070" to "100" found on the bottom right hand corner of the label. Only products with those datecodes are subject to recall. Each box also bears a net weight declaration and the message "Distributed by Nutritious Bread Company"
12) Media and consumers with questions about the recall should contact company representative, Wong Jin Loong, at 987654321.
13) Description of disease-causing organism, health-risks and consequences. e.g. Salmonella spp. is a deadly pathogen and can cause fever, vomiting and nausea. Elderly contracting Salmonellosis are especially susceptible to death.
14) Recall procedure to be announced through newspaper [containing all the information from 1) to 13)] and news broadcast stating: "Nutritious Bread Company's product, Multigrain bread with Chicken filling has been found to cause Salmonellosis upon consumption. The company is recalling all its products and consumers are urged to return the products to the point of purchase. For more details, please refer to the company's website www.nutritiousbreadcompany.com.sg"


References: http://www.fsis.usda.gov/PDF/Recall_023_2007_Release.pdf
http://vm.cfsan.fda.gov/~mow/chap1.html

Justification of CCPs

Baking, P5. As it is the only process in bread-making that kills microbes, it is very critical that the purpose is achieved. Most microbes can survive at most till 80°C, while spores can survive up to 100°C. Therefore, it is important that the internal temperature of bread reaches 100 °C as the major bread ingredient, flour, is commonly associated with Bacillus cereus, which can exist as spores.


Cooling, P6. Baking ensures that the bread achieves commercial sterility and is safe for consumption. As there is no further heat treatment of the bread after cooling, it is important that cooling continues to maintain this sterility. For efficiency and effectiveness, cooling is done in open air. The cooling room is maintained in positive air pressure to prevent outside air from flowing in. Air from the outside carries microorganisms and foreign particles, which is undesirable if they land on the product.

Multigrain bread process step

Raw materials
water, olive oil, salt, flour, active dry yeast, multigrains (oats, flax seeds, sunflower seeds)

Storage
Olive oil: 25 °C, away from UV light in stainless steel tanks
Salt: 25 °C in tightly covered silo
Flour, multigrains: 25 °C,RH 40% in dry silo
Active dry yeast: In unopened packages; store at rtp
If opened; must be refrigerated or frozen in airtight containers

Process step

1) Dissolve yeast in warm water in.
2) Add flour, oil and salt.
3) Mix for 2 minutes on medium speed.
4) Stir in multigrain until well blended.
5) Proof for 40 to 45 minutes or until almost double.
6) Shape and scale as desired.
7) Proof for 30 minutes or until double.
8) Bake in oven at 190ºC for 40 minutes.
9) Cool on wire rack.

What is food safety???

Food is the basic of life and humans eat in order to survive.

However, with the prospering of the world, food is no longer a basic in life; it has become a form of appreciation and even a form of art, and higher expectations of food quality and safety are involved.

With the ever-improving standard of living, people are willing to pay more in order to get good food--fresh, safe and wholesome food. Putting that aside, the reason why there is so much emphasis on keeping food safe for consumption is to prevent foodborne illness and worse still, death. International organizations and government sectors such as WHO, USDA, FDA and Singapore's very own AVA have been set up to monitor and ensure that standards of food safety are achieved and the food are indeed safe.


Thus, to survive in the F&B industry, the most important aspect is to produce safe food.
Food safety comes first, before any other aspects such as nutrition and innovation.


Consider this: would you rather eat a healthy food that is unsafe for consumption or an unhealthy food that is safe for consumption?