Food Preservation for Control of Food-Bone Disease

Question 1

What are the 5 goals to food preservation?

Answer 1

1. preserve surplus of agricultural produce until it gets to market for sale
2. transportation of food long distances
3. decreased production costs and reduce food waste (increases efficiency of food systems)
4. allow a wide variety of food to be sold in all seasons year-round (improves food security and nutrition)
5. prevent food spoilage until it can be consumed

Question 2

What factors promote enzyme and microbial activity in food?

Answer 2

Food
Acid (pH)
Temperature

Time
Oxygen
Moisture

Question 3

How can acidity, temperature, oxygen, and moisture be manipulated to avoid food spoilage?

Answer 3

ACID - move pH up by adding alkaline liquids or down by adding acidic solution

TEMP - move food temperature up or down from the TDZ

O2 - modified atmosphere packaging, reduce O2 and incease CO2, completely remove O2 by airtight canning

MOISTURE - remove liquids or ad more solutes

Question 4

What is the point of freezing/chilling food? Heat treating/cooking?

Answer 4

frozen microorganisms are unable to multiply and become dormant, but do not die

kills bacterial pathogens

Question 5

What are the 6 major ways of heat treating or cooking food?

Answer 5

1. boiling
2. canning - cook and airtight seal (pressure cooker)
3. confit - cook meat in fat or oil, then immerse in fat or oil for long-term storage
4. jellying - solidify food by cooking with gelatin (no available water)
5. jugging - stewing
6. smoke roasting (pit BBQ) - seals outer layer of food being cured, making it more difficult for bacteria to enter

Question 6

What is modified atmospheric packaging?

Answer 6

process using gases like nitrogen, oxygen, or carbon dioxide to preserve foods by extending shelf life and preventing molecular breakdown of food

Question 7

What effect does low oxygen and high carbon dioxide packaging have? What 6 pathogens can survive these conditions?

Answer 7

limits growth of Gram-negative bacteria, molds, and aerobic microbes (Pseudomonas)

1. Campylobacter jejuni
2. Clostridium botulinum
3. E. coli
4. Salmonella
5. Listeria
6. Aeromoas hydrophila

Question 8

What effect does high oxygen and high carbon dioxide packaging have?

Answer 8

bacteriostatic and bactericidal effects by suppressing aerobes by high CO2 and anaerobes by high O2

Question 9

What is the point of reducing moisture in food? What are the 4 methods of doing this?

Answer 9

increases solute concentration in food and decreases water potential

1. sugaring
2. salting (curing) - reduced water availability
3. freeze-drying (lyophilization/cryodesiccation) - removes water then freezes it to form ice and is placed in a vacuum to convert ice into a vapor
4. dehydration (sun/oven) - evaporates water with heat

Question 10

What curing salts are commonly used for curing meat? Why are they used carefully? How are they differentiated from table salt?

Answer 10

potassium nitrate, sodium nitrite, sodium chloride

nitrate and nitrite bond to myoglobin, acting as a substitute for oxygen —> red

“Prague powder” is combined with sodium chloride and sodium nitrite dyed pink

Question 11

What alkaline and acidic solutions can be used to alter the pH to preserve food?

Answer 11

ALKALINE: lye (sodium hydroxide)

ACIDIC: fermentation with organic acid or alcohol (wine, cheeses, beers), pickling with vinegar

Question 12

What is pickling? What are the 2 types?

Answer 12

method of preserving food in an edible, antimicrobial liquid

1. CHEMICAL: brine, vinegar, alcohol, and vegetable oil are used to inhibit or kill bacteria while also being heated/boiled for saturation (corned beef, eggs)
2. FERMENTATION: organic acids, like lactic acid produced by Lactobacillales

Question 13

What are the 3 major food additives used to inhibit microorganism growth?

Answer 13

1. antimicrobials - kill microbes directly by disrupting membranes —> acetic acid, benzoic acid, natamycin, nisin
2. salts - calcium propionate, sodium nitrate/nitrite, sulfites, EDTA
3. antioxidants - remove free radicals that would caus spoilage and fat rancidity —> ascorbic acid, butylated hydroxyanisole/toluene, citric acid, sulfites, tertiary butylhydroquinone, tocopherols

Question 14

What are the 2 major irradiation agents used to preserve food? Does this affect the food?

Answer 14

1. beta particles: high-energy electrons
2. gamma rays - cobalt-60 or cesium-137

irradiated food does not and cannot become radioactive

Question 15

What is electroporation? How is it used in the US and Europe?

Answer 15

food is placed between 2 electrodes and a brief electric pulse is applied to enlarge the pores of cell membranes, killing pathogens and releasing their contents

• US: potato preservation
• EUROPE: fruit juice preservation

Question 16

What is hurdle technology? What are 5 examples?

Answer 16

method of ensuring that pathogens in food products can be eliminated or controlled by combining more than one approach

1. high temperature during processing - heating
2. low temperature during storage - chilling, freezing
3. increasing acidity - acid addition or formation
4. lowering water activity or redox potential - remove oxygen or add ascorbate
5. preservatives and biopreservatives - sorbates, sulfites, nitrites, competitive flora