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Micro > Introduction Lecture > Flashcards

Introduction Lecture Flashcards

1
Q

The good microorganisms

A

Add them to foods to they are there naturally

Used for food fermentation ?

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2
Q

Examples of good microorganism

A 
Cheese
Yogurt 
Sour cream 
Bread
Salami
Pickles
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3
Q

What is the goal of food fermentation ?

A

Preservation and/or creating unique flavors and textures

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4
Q

The bad microorganisms

A

Change foods and cause them to do bad or spoil

Affect aroma, texture and appearance of food

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5
Q

Examples of bad microorganism

A

Discolored,mushy or fuzzy vegetables
Sour milk
Slimy, putrid meat

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6
Q

The ugly microorganism

A

Pathogenic, cause illness ranging from mild to life threatening

May NOT affect sensory characteristics of the food

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7
Q

Examples of microorganism

A

Salmonella

E coli 0157: H7

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8
Q

Common side effects of ugly microorganism

A

GI symptoms
Diarrhea
Nausea
Vomiting

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9
Q

What is incubation period

A

From the time you are infected to the time that you show symptoms

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10
Q

Challenges with pathogens that have longer incubation period

A

You dont remember where and how you got it from

Collecting samples

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11
Q

Factors affecting microbial growth in foods

A

Intrinsic factors ( food environment

Extrinsic factors

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12
Q

What are intrinsic factors

A

Inherent parameter of foods that affect their microbiology

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13
Q

What are extrinsic factors

A

Properties of the storage environment that affect their microbiology

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14
Q

Examples of intrinsic factors

A 
General nutrient 
Water activity 
PH
Oxidation reduction potential 
Growth inhibitors in foods
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15
Q

What are general nutrient in intrinsic factor ?

A 
Water
Nitrogen 
Carbon for growth 
Carbon for energy
Oxygen 
Phosphorous , potassium, sulfur 
Cofactors, vitamins , trace minerals , micronutrient
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16
Q

Water activity

A

Ratio of vapor pressure of water in sample to vapor pressure of pure water at the same temperature

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17
Q

Formula for water activity

A

Aw=Ps/Pw

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18
Q

Water activity is always

A

Less than 1

19
Q

Water activity measure free water or bound water

A

Free water

20
Q

What is formula for relative humidity

A

RH=aw X 100

21
Q

Water activity for many bacteria

A

0.91

22
Q

Processing to reduce water activity

A

Drying-less than 10-15% moisture means no growth
Additives- solutes
Salt, sugar, alcohol ( glycerol)
Compound blending- both in food manufacturing and recipe development

23
Q

How does adding solutes is related to water activity

A

When you add solutes they bind to free water and will be unavailable so it lowers the water activity

24
Q

Classification of foods by acidity

A

Acid foods 4.5 or less

Low acid : above 4.5

25
Q

What are foodborne microorganisms?

A

Molds
Bacteria
Parasites
Viruses

26
Q

Molds

A

Multicellular organisms

27
Q

Bacteria

A

Single celled organisms that live independently

28
Q

Parasites

A

Intestinal worms or microscopic Protozoa that live in a host animal or human

29
Q

Viruses

A

Small particles that live and can only replicate in a host

30
Q

Where do foodborne pathogens live

A

Most are residents of intestinal tracts of human and animals

Some common in soils

31
Q

Pathogens that live in intestinal tract of humans and animals

A 
Salmonella 
Ecoli O157:H7
Shigella 
Campylobacter 
Viruses and parasites
32
Q

Foodborne pathogens that live in soils

A

Listeria monocytogenes
Bacillus cereus
Clostridium botulinum

33
Q

What are Extrinsic Factors?

A 
Temperature 
Relative humidity
Atmosphere of storage 
Physical state 
Additives
34
Q

Most important Extrinsic factor?

A

Temperature

35
Q

Low temperature

A

Prolong generation time and extend shelf life

36
Q

Hot temperature

A

Prevent microbial growth

37
Q

High temperature

A

Kill microorganisms and spores

38
Q

Goal of MAP

A

Slow respiration rates
Reduce microbiological growth
retard enzymatic spoilage

39
Q

How to achieve MAP

A

Reduce oxygen content
Increase carbon dioxide
Increase Nitrogen

40
Q

2 methods of MAP

A

Vaccum packaging

Gas packaging

41
Q

What does vacuum packaging do?

A

Result in headspace O2 of less than 1% and CO2 levels of 10-20% depending on tissue or microbial respiration

42
Q

What does Gas packaging do?

A

Extension of vacuum packaging

Replace the removal of air with another gases-usually N2 and Co2 or O

43
Q

Name some Edible Antimicrobial films

A

Zein
Bacteriocins
Nisin

44
Q

Nisin is particularly good for inhibition of

A

Listeria

Micro (9 decks)

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