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19 Cards in this Set

  • Front
  • Back
What is the major quality concern with irradiation of meat?
What is irradiation?
high frequency and low wavelength waves used to kill microorganisms and spores in food
What are the two types of radiation used in food processing? What are the technologies/materials used to achieve this? What is their penetration?
Gamma Rays:
Cobalt-60 (5yr half life) 3" penetration
Cesium-37 (30 yr half life)

High Energy Electrons: (10MeV)
"electronic pasteurization" -sure beam technology - 1 1/2" penetration

X-Rays (5MeV)

UV Rays (only used for surfaces, usually sanitation)
How do you decide the dose of radiation for a particular food? What are the doses called?
The smaller the object, higher the dose

Radurization: 0.7-2.5 KGy
Same kill level as pasteurization

Radicidation: 2.5-10KGy Medium dose

Radappertization: 30-40 KGy
Not typically used due to chgs in food quality. Achieves commercial sterilization
What are positives and negatives of using Cobalt-60 to irradiate foods?
Cheap to manage
More penetration than e-
Last long time

Old rods are left in plant, removal is difficult
Not environmentally friendly
Requires expensive upfront costs
What is the mechanism of irradiation to foods?
Produces free radicals in water that react with proteins and DNA. Reaction causes DNA disruption and cell death.
Name six non-thermal preservation methods
Gamma rays, high energy e-, UV Light, Pulsed high intensity light, electrical energy (electroporation), high hydrostatic pressure
What is pulsed high intensity light?
Pulsed light that is 20,000 times more intense than that of the sun. Reduces total microbial count by 1-3 logs.
Describe how Electroporation is done
Food is placed between two electrodes that apply a pulse of high voltage electricity through the food and kills the bacteria
What is the intensity of pressure when using HHP? What amount of pressure kills vegetative cells? Spores?
Pressure ranges from 300-1,700 MPa (mega pascal)

Vegetative cells are inactivated below 700MPa, spores above 700MPa
What are the limitations of using HHP?
Cannot be used for all foods (some solid foods lose quality characteristics), Effectiveness tails off after a certain exposure time
What are HHP's biological effects on Microbial cells?
Protein denatures at >400MPa

Cell membrane disruped

Ribosomes inactivated

Enzymes involved in spore germination inactivated
Why is HHP not a completely "cold" process?
Because pressure is disributed in short bursts. Pressure naturally raises the temperature of the food, so there is a slight termal component to the process.
What are the three major categories of chemical preservation?
Food additives, fumigants, and sanitizers
Name 5 chemical preservatives
You Could Answer:
Benzoic Acid
Propionic Acid
Sorbic Acid
Sodium Nitrite
Sodium Diacetate
When are organic acids effective in reducing bacterial counts?
They are useful when the pH is at or below the pKa (the pH at which equal amts of charged and uncharged acids are present). Only unprotonated compounds can enter the cell membrane and make it to the cytoplasm.
What is the mechanism of organic acids being absorbed into the cytoplasm
Unprotonated acid passes through cell membrane

neutral cytoplasm causes acid to disassociate. Release of proton acidifies cytopasm. ATP is used by cell to pump out protons, maintaining netural pH. This uses up ATP needed for growth.
Give characteristics of Benzoic Acid, its effect on cells and uses in foods.
First anti-microbial

naturally present in plants

effective at pH<4.5

inhibits yeasts and molds

Dissapates the Proton Motive Force
Disrupts Transport

Cereals, Jams, Cheeses, Snacks, Candy
Give characteristics of Propionic Acid, its effect on cells and uses in foods.
Naturally produced in cranberries

Effective at pH<4.5

Most effective versus fungi & molds

Dissapates PMF
Disrupts transport

Breads, bakery products, cheeses