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Food Preservation

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Bridget Xie

on 20 November 2013

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Transcript of Food Preservation

Food Preservation
History of Food Preservation
one of the oldest technologies used by every culture
kept food fresh for later consumption
many early methods of food preservation included:
- drying
- freezing
- salting
- smoking
Food Preservation Today
many methods used in the past are still used today
new research into food preservation began in the early 1800's
the conditions during World War II lead to major advancements in technology
-ex. jarring food at home
important component of society
What is Food Preservation?
methods that slow down/prevent food from spoiling
due to bacteria, fungi or oxidation of fat
General methods:
- temperature change
- chemicals
- fermentation
- use of machines
proteins that affect the rate of decomposition by acting as a catalyst
has a fold that acts as a pocket to produce a product from two different substrates
new product causes a change in concentration, increasing the rate of reaction
results in food spoiling or discolouring quickly
Refrigeration and Freezing
most common form of food preservation
low temperatures slow down enzyme activity and bacterial growth
temperatures below zero leave bacteria inactive
their activity is drastically decreased when not in ideal conditions
enzymes are fragile and easily denatured through:
- temperature change
- pH change
- chemicals
- radiation
Food Temperature Danger Zone
> 75 °C
Most bacteria die within seconds
60 °C - 74 °C
Bacteria are "frozen", they are not killed but do not multiply either
4 °C - 59 °C
1 °C - 4°C
Bacteria still multiply but at a much slower rate
< 0°C
Bacteria are not killed but do not multiply either
Flash Freezing
r= Δc/Δt
freezing food as fast as possible to prevent large ice crystals
preserves better and maintains a more firm and natural texture as opposed to slow freezing
invented by Louis Pasteur in the 1860's
psychrotrophs are killed at high temperatures
63°C - 65°C for 30 min or
90°C - 140°C for one second
gets rid of the need for refrigeration
lactic acid ferments lactose to lactic acid
pH levels in milk are ideal for bacterial growth
fermentation spoils the milk to an edible product
ancestors knew how to use the fermentation to produce cheese
1. Lactic acid bacteria turn lactose to lactic acid, lowing the pH of the milk
2. Increased acidity stops bacteria from growing
3. Enzyme called rennet separates the curd and whey
4. Whey is drained and curds are pressed to remove excess whey
Salting and Drying
osmosis draws out moisture
dry environments are not ideal for bacteria
r= ∆c/Δt
Chemical Preservatives
unnatural and synthetic but more effective
various health implications and more that are not yet known
BHA and BHT are used to prevent fats and oils from going rancid by oxidizing with oxygen
found in foods such as butter, meat, cereal, gum
also commonly used in cosmetics, rubber products and food packaging
both are derived from petroleum
known as the two most dangerous preservatives
may be carcinogenic
banned in Australia, Japan, Sweden
warning labels are mandatory in California
limit consumption to 1 gram/day
numerous studies over the past 40 years
reduces number of microorganisms without compromising texture, taste or nutritional value
radiation in the form of high energy electrons, gamma rays or X-rays
usually done with raw meat, fresh foods and spices
Radioactive Food?!?
harmless to food
source of radioactivity comes from Cobalt-60
recommended for patients with very low immune systems
and American astronauts
Product Developer
improve food products
invent brand new products
involves a lot of lab work
need a background in biology, chemistry and food science
$45,000- >$110,000
Average: $70,000
Food developers at the University of Guelph invented:
double churned ice cream
Omega-3 eggs
Yukon Gold Potato
must have determination and charisma
good at handling money and making connections
Bob Crane, CEO of N2Ingredients
packages and mixes products for food companies
test kitchen for new products such as gluten free bread
Ranked by Profit Magazine as one of Canada's Top 50 emerging growth companies 5 out of the past 7 years
A member of QuantamShift, an entrepreneurial association
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Brain, Marshall . "How Food Preservation Works." HowStuffWorks. N.p., n.d. Web. 16 Nov. 2013. <>.
"Discovery Health." 'Discovery Fit & Health : Sara Novak'. N.p., n.d. Web. 15 Nov. 2013. <>.
"Early methods of food preservation." Early methods of food preservation. American Chemical Society, n.d. Web. 13 Nov. 2013. <>.
"Food Preservation." Boundless. N.p., n.d. Web. 16 Nov. 2013. <>.
"Food Preservation." World of Microbiology and Immunology. N.p., n.d. Web. 14 Nov. 2013. <>.
"Food Science." Microorganisms in Milk. University of Guelph, n.d. Web. 15 Nov. 2013. <>.
Helmenstine, Anne. "BHA and BHT." Chemistry. N.p., n.d. Web. 16 Nov. 2013. <>.
Nummer, Brian . "Historical Origins of Food Preservation." National Center for Home Food Preservation. N.p., n.d. Web. 18 Nov. 2013. <>.
"Photo Gallery." N.p., n.d. Web. 16 Nov. 2013. <>.
"Potential Career Paths and Salaries." Food Science Major (Penn State University). N.p., n.d. Web. 17 Nov. 2013. <>.
"Preserving food." Preserving food. N.p., n.d. Web. 16 Nov. 2013. <>.
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