MICROBIOLOGY > EXERCISE 8 > Flashcards

EXERCISE 8 Flashcards

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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
Is sterilized milk free from microorganisms?
Yes
26
4 processes that sterilized milk
1. filtration 2. clarification 3. homogenization 4. sterilization
27
Temp and Time for sterilized milk
150 C ( 9 Seconds)
28
Shelf-life of sterilized milk
1 year at room temp
29
TYPES OF MILK ACCORDING TO PROCESSING the # of microorganisms is reduced
pasteurized milk
30
TYPES OF MILK ACCORDING TO PROCESSING pathogens are killed
pasteurized milk
31
TYPES OF MILK ACCORDING TO PROCESSING have a shelf-life of a week or longer when kept refrigerated
pasteurized milk
32
Who defined pasteurization as a process of heating liquid?
Redmond
33
What temperature are milk pasteurized?
55 C to 70 C
34
Significance of Pasteurization
Destroys harmful bacteria without changing the: - composition - flavor - nutritive value
35
What was introduced as a public health measure to destroy human pathogens
Milk pasteurization
36
3 types of pasteurization methods - meaning - temperature - shelf life
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
Also known as Flash point method
HTST
38
2 quantitative methods for assessing milk quality
1. Plate count / Viable cell count 2. Breed count
39
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK Counts the number of cell/units that are capable of forming a colony
Plate count
40
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK reported as CFU/mL
Plate count
41
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK Counts only VIABLE CELLS
Plate count
42
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK Underestimation
Plate count
43
4 ASSUMPTIONS for Plate count
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
What are thermoduric bacteria?
Able to survive heat treatment during pasteurization
45
4 advantages of plate count
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
Does the SPC only provide an ESTIMATE of the total population?
Yes
47
4 limitations of SPC
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
In SPC, what does short incubation time signify?
Fewer than maximum number of colonies can form
49
Is SPC diluted before plated?
Yes
50
Plated Dilution Formula
Plated Dilution = Dilutions Made x Amount Inoculated
51
CFU / mL Formula - if from one dilution - if from 2 dilutions
- one dilution cfu/ml = (average # of cfu x df) / volume plated - 2 dilutions: check messenger
52
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK microscopic method
breed count
53
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK counts both living and dead
breed count
54
TYPES OF QUANTITATIVE MICROBIAL ASSESSMENT OF MILK overestimation
breed count
55
4 advantages of breed count
- 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
4 disadvantages of breed count
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
Acts to dissolve fat globules in milk
Xylol
58
In breadcount, what is the area of the sq where u put the milk sample?
1 cm 3
59
How many FOVs are used in breed count
10 FOVs
60
Qualitative method used to assess milk quality
Resazurin reduction Test
61
What method is the fastest and easiest way of assessing quality of milk
Resazurin Reduction Test
62
On what process is Resazurin reduction Test based on?
occurrence of dye reduciton
63
How much sample does breed count use?
Loopful of wire 0.01 mL
64
Relationship between TIME FOR DYE REDUCTION and NUMBER OF ORGANISMS IN SAMPLE
inversely
65
3 Advantages of Resuzurin Reduction Test
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
3 disadvantages of Resuzurin Reduction Test
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
How many times do you invert the tubes in resazurin
2 times
68
How long is incubation + temp in Resazurin Reduction Test
37 C for 1 hr
69
statutory limits for coliforms
not exceed 100 coliforms
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