Food Preservation and Storage

Question 1

microbial growth and food spoilage results from…..

Answer 1

Growth of Microbes in Food

• alters food visibly and in other ways, rendering it unsuitable for consumption
• Different foods undergo different types of spoilage processes
• Toxins are sometimes produced

Question 2

microbial growth is controlled by 2 factors: what are they?

Answer 2

1. ) intrinsic factors
   - factors related to the food itself
2. ) extrinsic factors
   - environment where food stored

Question 3

describe intrinsic factors concerning carbohydrates

Answer 3

Mold predominates

• degrades food by hydrolysis
• little odor
• ergotism (hallucination or may even cause death)

Question 4

describe intrinsic factors concerning proteins or fats (4)

Answer 4

• Bacterial growth predominates
• Putrefaction: proteolysis and anaerobic breakdown of proteins; foul smelling amine compounds
• Unpasteurized milk spoilage: acid production followed by putrefaction
• Butter: short-chained fatty acid production; rancid butter

Question 5

describe intrinsic factors concerning pH

Answer 5

impacts make up of microbial community and therefore types of chemical reactions that occur when microbes grow in food
e.g., low pH favors yeast and mold

Question 6

describe intrinsic factors concerning presence and availability of water

Answer 6

in general, lower water activity inhibits microbial growth

Question 7

describe physical structure concerning intrinsic factors (4)

Answer 7

• grinding and mixing distribute microbes; promotes microbial growth
• outer skin of vegetables and fruits slows microbial growth

Question 8

some foods contain natural antimicrobial substances. Name some (5)

Answer 8

Coumarins – fruits and vegetables
Lysozyme – cow’s milk and eggs
Aldehydic and phenolic compounds – herbs and spices
Allicin – garlic
Polyphenols – green and black teas

Question 9

Name 3 extrinsic factors and describe them

Answer 9

1. ) Temperature
   - lower temperatures retard microbial growth
2. ) Relative humidity
   - higher levels promote microbial growth
3. ) Atmosphere
   - oxygen promotes growth
   - modified atmosphere packaging (MAP)
   - use of shrink wrap and vacuum technologies to package food in controlled atmospheres

Question 10

what is filtration

Answer 10

• Method of preservation

- Water, wine, beer, juices, soft drinks, and other liquids usually by filtration

Question 11

describe low temperature in relation to preservation (2)

Answer 11

• Refrigeration at 5°C retards but does not stop microbial growth: microorganisms can still cause spoilage with extended storage
• Freezing – at - 20°C for longer storage

Question 12

describe pasteurization in relation to preservation (3)

Answer 12

• Kills most human pathogens and substantially reduces number of spoilage organisms
• Different pasteurization procedures heat for different lengths of time
• shorter heating times result in improved flavor

Question 13

describe water availability in relation to preservation

Answer 13

Dehydration

e. g., lyophilization to produce freeze-dried foods is commonly used to eliminate bacterial growth
e. g., salting - food preservation occurs as a result of free-water loss and an increase in solute concentration

Question 14

describe chemical based preservation

Answer 14

1. ) GRAS
   - chemical agents “generally recognized as safe”
   - agents include organic acids, sulfite, ethylene oxide gas, ethyl formate
   - sodium nitrite – inhibits spore formation in meats, forms nitrosamines
2. ) pH of food impacts effectiveness of chemical preservative

Question 15

describe radiation as a preservation method

Answer 15

Radappertization

• use of ionizing radiation (gamma radiation) to extend shelf life or sterilize meat, seafoods, fruits, and vegetables
• excellent penetrating power – food not rendered radioactive

Question 16

slide 19

Answer 16

look at :)

Question 17

what are the 2 types of food-borne disease?

Answer 17

1. ) food-borne infection

2. ) food intoxications

Question 18

what are 3 ways food-borne diseases are transmitted?

Answer 18

1. ) breakdown in hygiene
2. ) fecal-oral route key
3. ) fomites also important

Question 19

describe food-borne infection (2)

Answer 19

-Ingestion of pathogen, followed by growth, tissue invasion, and/or release of toxins
-Raw foods (e.g., sprouts, raspberries, and seafood) are important sources
(slide 22)

Question 20

describe food-borne intoxications (3)

Answer 20

• Ingestion of toxins in foods in which microbes have grown
• Produce symptoms shortly after the food is consumed because growth of the disease-causing microorganism is not required
• Include staphylococcal food poisoning, botulism, Clostridium perfringens food poisoning, and Bacillus cereus food poisoning

Question 21

slides 24 and 25

Answer 21

thats all!