Download Food Chemistry

Food Chemistry
Chapter 17 in Green / Damjii
Chapter X in Nuess
Chapter X in Oxford Study
(no resource in Chang)
F.5: Genetically Modified Food
Homework
• Read F5– GM Foods- pp. 486
• Do Qs 34-37
• on p 493
F.5.1: Define a genetically modified (GM) food.
• Genetically modified food is a food that is
produced by modifying the DNA sequence of
micro-organisms, plants and animals.
• Genetic engineering in plant foods may involve…
– Put a gene in to change behavior of cell
– Inactivate a gene to remove undesired behavior
– Modify a gene to get higher yields of products
F.5.1: Define a genetically modified (GM) food.
• Genetic engineering may be used
– Directly – develop a transgenic plant / animal
• Plants resistant to herbicides, contain more vitamins,
can grow in poor soils or harsh conditions
– Indirectly – produce enzymes for food processing
using genetically modified micro-organisms
• GM bacteria make enzyme (protease chymosin) to help
convert milk into cheese – reducing the need for rennet
from the stomachs of calves.
• Ascorbic acid, aspartame, caffeine-free coffee
F.5.2: Discuss the benefits and concerns of
using GM foods.
ADVANTAGES
(1) Pest, herbicide, and disease resistance
 Reduce need to use herbicides, pesticide, vaccines… all of
which add to production costs, may impact our
environment, and may leave their own toxic residues in
food.
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Ex: Crop is made to be more resistant to a particular herbicide
so that less of the herbicide needs to be used to get rid of weeds
Ex: Bananas have gene that resists attack by nematods
Ex: Potatoes have gene added to resist fungal disease
F.5.2: Discuss the benefits and concerns of
using GM foods.
ADVANTAGES
(2) Improved qualities and range

Enable a food to be grown in a wider range of climatic
conditions (drought, high salt content in soil &/or
groundwater) ... produce greater yields… mature in a shorter
time.
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Ex: tobacco and potato plants get a gene that makes them more
cold tolerant
Ex; higher yielding rice varieties &/or rice that contains additional
vitamins and minerals to prevent nutrient deficiencies
Ex: maize that can grow in areas with lower rainfall
Ex: FlavrSavr tomato – PG gene is inhibited allowing tomato to stay
firm longer… to allow for harvesting, storage, and distribution…
tomato is still able to ripen… just not loose its firmness.
F.5.2: Discuss the benefits and concerns of
using GM foods.
DISADVANTAGES
(1) Possible impact on health
 Subtle differences in composition may cause allergic
reactions in people
 Unknown impact on our digestive system ???
(2) Possible damage to natural ecosystems
 Currently gm plants are limited to particular farms… but
there is a risk that pollen from them will escape into the
wild population with unforeseen consequences.