Midterm Flashcards
Food irradiation
“The idea of using ionizing radiation in food preservation destroy pathogenic and spoilage microorganisms in food
How does food radiation work?
Ionizing radiation is produced by Cobalt-60 in the form of gamma rays.
• The energy transmitted by the gamma rays alters the structure of the DNA in microorganisms which prevents their growth and reproduction.
Food irradiation in Canada
World leader in irradiation technology but limited commercial food irradiation facilities
Usage severely restricted in Canada
Approved applications of food irradiation in Canada are
Potatoes (1960)
To inhibit sprouting during storage
Onions (1960)
To inhibit sprouting during storage
Wheat, flour, whole wheat flour (1965)
To control insect infestation during storage
Spices and dried seasoning preparations
To reduce microbial load
Only meat allowed radiation in Canada
Ground beef fresh and frozen
The US-FDA and USDA have allowed the following foods to be irradiated:
Packaged refrigerated or frozen red meat
To control pathogens and extend shelf-life
Packaged poultry
To control pathogens
Fresh fruits, vegetables, and grains
To control insects, and inhibit growth, ripening , and sprouting
Pork
To control trichinosis
Misconceptions about food irradiation
Irradiated foods will become radioactive or “glow in the dark”.
• Your teeth don’t become radioactive after an x-ray, and your luggage doesn’t “glow” after going through security checks. Irradiated food is severely altered.
• The minor changes tend to be less than the changes created by traditional cooking processes.
The industrial revolution started around
1780s to late 1800s
Steam engine created by
James Watt
* Patented 1791 (10 horsepower)
* 10,000 horsepower by 1890’s
Iron processing
New techniques:
* Rolling mills replaced hammering
* Advances in furnaces etc.
* Huge impact on industrialization.
Textile industry
Cotton gin (USA)
* Eli Whitney (1793; patented 1794)
* Power looms etc
Napolean did what
Offered a prize of 12,000
francs for new method to
preserve food.
What did nicholas appert do during the napoleonic wars
Nicholas Appert (1749-1841)
published an article in 1804 on
“The Art of Preserving Animal
and Vegetable Substances”.
* He found that foods heated in
sealed containers would not
spoil as long as the containers
remained closed.
how did nicholas appert win
Appert won prize in January
1810 with product heated in
sealed glass bottles.
* Bottles were wrapped in canvas
to prevent breakage.
* Process was called
“Appertization”.
Who developed tin can?
British inventor Peter Durand
Who else found perservation
Lazzaro
Spallanzini and carl wilhelm scheele
thomas Malthus growth model
Believed the capacity of humans to
reproduce would outstrip their ability
to produce food if population growth
rates of the time were to continue.
French wine disaster
In early 1860’s, the French wine
industry was on the verge of
collapsing due to unknown and
unwanted contaminants.
* Problem had severe impact on
export of wines.
Plate heat exchangers
Volumetric heating
Heating by conduction, using temperature gradient where inner core tends to be unheated
Traditional heating
Uniform heating no temperature gradient
Polar Nature of Water
Oscillation of polar molecules is induced by alternating electromagnetic field.
- Rapid oscillation within the water creates “friction” at molecular level which induces heating.
Ohmic heating
Passing electric current through water caused the temperature to rise
Most foods contain more than 80%
water by weight, plus dissolved solutes
that act as electrolytes to conduct an
electric current.
* This would suggest that the application
of an electric current would cause them
to heat up
Pulsed electric field processing
Original development took place in the
1920’s with a process to pasteurize milk
by passing it between two carbon
electrodes and subjecting it to short
electric discharges of up to 4,000 volts.
How does Pulsed electric field processing kill microogranisms
By rupturing cell memebrane
High pressure Processing (HPP)
Hite showed that 450 MPa
(i.e., 4,400 atmospheres or 65,000 psi)
could improve the keeping properties of
milk.
* Interest faded for considerable period of
time.
* Recent renewed interest. The pressure exerted on a
dime would be equivalent to
17,400 to 34,800 pounds.
Why is there water inside the high
pressure processing chamber?
* Why not just have air inside the chamber
so that the product does not get wet?
Water is denser making it easier for travel whereas the air would compress easily. It can evenly distribute the pressure on the product
High Pressure can inactivate
degradative enzymes that are present in
fruits by
break down the larger
molecules and damage the food product’s quality and functionality.
High pressure processing changes the
conformation of the enzymes which leads to their inactivation.
* The result is longer shelf-life with improved quality.
- can kill vegetative -microogranisms by damaging their cell walls.
