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MICROBIOLOGY > EXERCISE 8 > Flashcards

EXERCISE 8 Flashcards

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Biology 101 flashcards
1
Q

Are milk immediately gained from healthy animals nutritious?

A

Yes

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2
Q

5 nutrients found in milk

A
  1. casein (protein)
  2. fat
  3. lactose
  4. glucose
  5. B vitamins
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3
Q

What is the ideal growth medium for microorganisms?

A

Milk

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4
Q

Milk directly secreted from udder of healthy cow

VS

freshly drawn milk

A

yung una should be free from microorganisms

yung pangalawa merong microbes na dahil pwede nanggaling sa bucket kung san linagay yung milk, or sa kamay nung kumuha /// or sa mismong udders and skin ng cow

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5
Q

3 importance of microorganisms in milk

A
  1. Pathogens may constitute health hazards
  2. Presence of spoilage microorganisms
  3. LAB may contribute to preservation of milk
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6
Q

2 TYPES of microorganisms present in milk

A
  1. Spoilage microorganisms
  2. Pathogenic microorganisms
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7
Q

What type of microorganisms are responsible for the “souring” of milk?

A

Spoilage Microorganisms

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8
Q

TYPES OF SPOILAGE MICROORGANISMS

A
  1. Lactobacillus species (& coliforms)
  2. Psychrotrophic microbes (Pseudomonas sp.)
  3. Achromobacter
  4. Alcaligenes
  5. Flavobacterium spp
  6. Streptococcus lactis
  7. Klebsiella aerogenes
  8. Enterobacter liquefasciens
  9. coliform bacilli
  10. Geotrichum candidum
  11. Yeasts
  12. Serratia marcescens
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9
Q

What specific microbe contributes to milk spoilage through production of ______ and _________ enzymes

A

LIPOLYTIC & PROTEOLYTIC

Pseudomonas spp.

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10
Q

What is a pneumonia-like infection from urine, feces, milk, and body fluids of domestic animals

and what specific pathogenic microorganism causes this?

A

Q-Fever

Coxiella burnetti

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11
Q

What pathogenic microorganisms do not multiply in milk but survive in unpasteurized milk and milk products?

A

Mycobacterium tuberculosis

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12
Q

M. tuberculosis

  • spore-forming or not?
  • heat-resistant or not?
  • how to kill?
  • what enzyme to inactivate to ensure death of microbe?
A
  • non-spore-forming
  • very heat resistant
  • low pasteurization
  • alkaline phosphatase
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13
Q

Disease-causing microorganisms that may be found in milk: (5)

A

1) Staphylococcus (from mastitic cow)
2) Listeria monocytogenes (causes spontaneous abortion)
3) Mycobacterium tuberculosis
4) Coxiella burnetti – causes Q fever
5) Brucella- causes brucellosis/undulant fever

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14
Q

What 3 pathogenic microbes are used to standardize pasteurization process?

A
  1. Mycobacterium tuberculosis
  2. Coxiella burnetti
  3. Brucella
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15
Q

What is the maximum temp and time that the ff can survive:

  1. Coxiella burnetti
  2. Mycobacterium tuberculosis
A
  1. 62.8 C (20 mins)
  2. 55 C (30 seconds)
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16
Q

3 types of milk according to processing:

A
  1. Raw Milk
  2. Sterilized Milk
  3. Pasteurized Milk
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17
Q

TYPES OF MILK ACCORDING TO PROCESSING

not processed

A

raw milk

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18
Q

TYPES OF MILK ACCORDING TO PROCESSING

contains microorganisms from animal and handlers and utensils

A

raw milk

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19
Q

TYPES OF MILK ACCORDING TO PROCESSING

very short shelf-life

A

raw milk

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20
Q

5 major parameters used to regulate quality of RAW MILK production

A
  1. Mastitis diagnosis (through somatic cell counts and microbiological analysis)
  2. Determination of microbial counts in bulk tank milk
  3. Testing for veterinary drugs and aflatoxins
  4. Spoilage/Determination of total viable counts
  5. Determination of psychrotrophic or thermoduric microorganisms
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21
Q

Is pasteurization absolute?

A

No, some microbes will still remain

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22
Q

TYPES OF MILK ACCORDING TO PROCESSING

treated with heat to kill all microorganisms

A

sterilized milk

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23
Q

TYPES OF MILK ACCORDING TO PROCESSING

undergoes a series of filtration, homogenization, clarification, and sterilization

A

sterilized milk

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24
Q

TYPES OF MILK ACCORDING TO PROCESSING

milk stays fresh for a very long period

A

sterilized milk

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25
Q

Is sterilized milk free from microorganisms?

A

Yes

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26
Q

4 processes that sterilized milk

A
  1. filtration
  2. clarification
  3. homogenization
  4. sterilization
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27
Q

Temp and Time for sterilized milk

A

150 C ( 9 Seconds)

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28
Q

Shelf-life of sterilized milk

A

1 year at room temp

29
Q

TYPES OF MILK ACCORDING TO PROCESSING

the # of microorganisms is reduced

A

pasteurized milk

30
Q

TYPES OF MILK ACCORDING TO PROCESSING

pathogens are killed

A

pasteurized milk

31
Q

TYPES OF MILK ACCORDING TO PROCESSING

have a shelf-life of a week or longer when kept refrigerated

A

pasteurized milk

32
Q

Who defined pasteurization as a process of heating liquid?

A

Redmond

33
Q

What temperature are milk pasteurized?

A

55 C to 70 C

34
Q

Significance of Pasteurization

A

Destroys harmful bacteria without changing the:
- composition
- flavor
- nutritive value

35
Q

What was introduced as a public health measure to destroy human pathogens

A

Milk pasteurization

36
Q

3 types of pasteurization methods

  • meaning
  • temperature
  • shelf life
A

LTH (Low temperature hold)
- 63-66 C
- 30 minutes
- short life products

HTST (High temperature short time)
- 72 C
- 15 seconds
- refrigerate

  • both are cooled to not more than 10 C

UHT (Ultra high temperature)
- 133 C
- 1 second
- stored at room temp (longest shelf life as long as w seal)

37
Q

Also known as Flash point method

A

HTST

38
Q

2 quantitative methods for assessing milk quality

A
  1. Plate count / Viable cell count
  2. Breed count
39
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

Counts the number of cell/units that are capable of forming a colony

A

Plate count

40
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

reported as CFU/mL

A

Plate count

41
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

Counts only VIABLE CELLS

A

Plate count

42
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

Underestimation

A

Plate count

43
Q

4 ASSUMPTIONS for Plate count

A
  1. Each bacterium grows to produce a single colony
  2. Original inocolum is homogenous
  3. No aggregate of cells
  4. Plate count = level of thermoduric bacteria
44
Q

What are thermoduric bacteria?

A

Able to survive heat treatment during pasteurization

45
Q

4 advantages of plate count

A
  1. Simple
  2. Counting of viable organisms only
  3. Accurate for milk w low bacterial content
  4. Adaptability to counting specific types of bacteria
46
Q

Does the SPC only provide an ESTIMATE of the total population?

A

Yes

47
Q

4 limitations of SPC

A
  1. NOT all viable bacteria are presented (only those that can grow in particular physical environments)
  2. 1 Cell is not equal to 1 colony
  3. Erroneous measurements (due to crowded colonies fusing)
  4. Depends on inoculum and culture media conditions + colony size (what the eye can see)
48
Q

In SPC, what does short incubation time signify?

A

Fewer than maximum number of colonies can form

49
Q

Is SPC diluted before plated?

A

Yes

50
Q

Plated Dilution Formula

A

Plated Dilution = Dilutions Made x Amount Inoculated

51
Q

CFU / mL Formula

  • if from one dilution
  • if from 2 dilutions
A
  • one dilution

cfu/ml = (average # of cfu x df) / volume plated

  • 2 dilutions: check messenger
52
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

microscopic method

A

breed count

53
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

counts both living and dead

A

breed count

54
Q

TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK

overestimation

A

breed count

55
Q

4 advantages of breed count

A
  • results after 10-15 minutes
  • minimum amount of equipment
  • morphological types of bacteria can be identified
  • slides can be kept as permanent record of sample
56
Q

4 disadvantages of breed count

A

counts cannot be made accurately on low count milk
- dead cells and debris are counted
- tiring to the technician
- organisms may not stand out clearly in microscopes

57
Q

Acts to dissolve fat globules in milk

A

Xylol

58
Q

In breadcount, what is the area of the sq where u put the milk sample?

A

1 cm 3

59
Q

How many FOVs are used in breed count

A

10 FOVs

60
Q

Qualitative method used to assess milk quality

A

Resazurin reduction Test

61
Q

What method is the fastest and easiest way of assessing quality of milk

A

Resazurin Reduction Test

62
Q

On what process is Resazurin reduction Test based on?

A

occurrence of dye reduciton

63
Q

How much sample does breed count use?

A

Loopful of wire

0.01 mL

64
Q

Relationship between

TIME FOR DYE REDUCTION and NUMBER OF ORGANISMS IN SAMPLE

A

inversely

65
Q

3 Advantages of Resuzurin Reduction Test

A
  1. big bulk mof milk can be used to determine quality
  2. simple, rapid, and inexpensive
  3. only viable cells actively reduce the dyes
66
Q

3 disadvantages of Resuzurin Reduction Test

A
  1. rate of decolorization/reduction of the indicator
    dye is influenced by the kind of microorganisms
    present
  2. existence of inherent reductive substances in
    some food
  3. test conditions favor the growth of mesophiles
67
Q

How many times do you invert the tubes in resazurin

A

2 times

68
Q

How long is incubation + temp in Resazurin Reduction Test

A

37 C for 1 hr

69
Q

statutory limits for coliforms

A

not exceed 100 coliforms

MICROBIOLOGY (30 decks)

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