Course:FNH200/Lessons/Lesson 09/Page 09.4

From UBC Wiki
Jump to: navigation, search

9.4 Genetically Modified Organisms, Novel Foods and Biotechnology-Derived Foods

Start this part of the lesson by completing the following activity.

Critical Thinking
Look at the list of ingredients on a package of Cheddar cheese.
  • You will note that microbial cultures and rennet and/or pepsin and/or microbial enzymes are listed. The supply of calf rennet falls short of the demand. Some cheese processors use a mixture of rennet and hog pepsin (extracted from the stomachs of slaughtered hogs) or microbial rennets (proteinases with rennet-like properties produced by selected microorganisms). The substitute rennets, however, do not produce Cheddar cheese of as high quality as that produced with calf rennet.
  • A good deal of research worldwide is directed at finding enzymes which could replace calf rennet. This includes production of calf chymosin by genetic engineering of microorganisms.
  • Once again, please note that rennin and chymosin are pure form of enzyme and rennet refers to the preparation containing the pure enzyme along with other materials.

Check out the required additional readings - excerpts from Justice Canada website: Food and Drug Regulations Part B Foods (Links to an external site.), Division 8 Dairy Products, B.08.030 to B.08.033 on cheese and Division 16, Food Additives (Table V Food Additives that may be used as Food Enzymes).

  • What "shall" cheese consist of? What "may" it contain?
  • What enzymes are permitted as food additives in cheese? Have a look at the below excerpt from the Food and Drug Regulations, B.08.033 (3)
    • (3) No person shall use an enzyme other than (a) aminopeptidase derived from Lactococcus lactis, bovine rennet derived from aqueous extracts from the fourth stomach of adult bovine animals, sheep and goats, chymosin A derived from Escherichia coli K-12, GE81 (pPFZ87A), chymosin B derived from Aspergillus niger var. awamori, GCC0349 (pGAMpR) or from Kluyveromyces marxianus var. lactis, DS1182 (pKS105), lipase derived from Animal pancreatic tissue; Aspergillus niger var.; Aspergillus oryzae var.; Edible forestomach tissue of calves, kids or lambs; Rhizopus oryzae var. or from Aspergillus oryzae (MLT-2) (pRML 787) (p3SR2); Rhizomucor miehei (Cooney and Emerson) (previous name: Mucor miehei (Cooney and Emerson)); Rhizopus niveus, milk coagulating enzyme derived from Rhizomucor miehei (Cooney and Emerson) (previous name: Mucor miehei (Cooney and Emerson)), from Mucor pusillus Lindt by pure culture fermentation process or from Aspergillus oryzae RET-1 (pBoel777), pepsin derived from glandular layer of porcine stomach, phospholipase derived from Aspergillus oryzae (pPFJo142), protease derived from Micrococcus caseolyticus var. or rennet derived from aqueous extracts from the fourth stomach of calves, kids or lambs, in the manufacture of any cheese to which subsection (1) applies;

What are GMOs and GEs?

Genetically Modified Organisms ("GMOs") are plants, animals and microorganisms in which there is a change to the heritable trait(s) of the organism by intentional manipulation. This intentional manipulation includes but is not limited to the use of modern gene technologies such as recombinant nucleic acid technology. Genetically engineered organisms are more specific and through this technology, a foreign piece of DNA (deoxyribonucleic acid) is inserted into the genetic material of the host organisms.

Genetic modification may enable the host organism to

  • yield a desired product (e.g. bovine chymosin produced by genetically modified bacteria), or
    • possess a desired characteristic (e.g. tolerance to a specific herbicide in genetically modified canola plants, insect resistance in corn genetically modified to produce the insect toxin produced by Bacillus thuringensis, Bt; canola plants genetically modified to produce oil with specific compositional characteristics)

Genetic engineering and cheese

Recombinant chymosin

  • Recent developments have enabled transfer of the gene from calves that encodes for the enzyme chymosin to specific microorganisms selected for enzyme production.
    • The microorganisms are cultured in large fermenters and produce the chymosin which is then isolated, purified and sold to the dairy industry for cheese making.
    • Microbially produced bovine chymosin is an approved food additive in Canada. Chymosin is the principle milk-clotting enzyme in bovine rennet extracts that have traditionally been used in cheese making.

Genetically engineered starter cultures

  • Research is also being conducted to improve fermentative capabilities of lactic acid bacteria and other bacteria and moulds used in cheese making.
    • Some of that research involved genetic engineering where genes encoding for increased resistance to bacterial viruses (bacteriophage, a potentially serious problem in cheese making which can cause starter culture failure), improved enzymatic activity (lactose utilization; production of desirable proteinases involved in cheese ripening) are transferred into bacteria used as starter cultures.
    • Genetically improved starter cultures produced through genetic engineering must go through thorough testing and evaluation to demonstrate their safety prior to approval for their use in foods (they are classified as food additives).

There is a great deal of public concern and controversy about genetically modified foods and genetically modified organisms (these have been dubbed as Frankenfoods by opponents to the technology and the concept).

Want to learn more?
To make an informed personal decision regarding whether or not you would accept (some or all) GM foods, please visit the following websites: