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FOOD TECHNOLOGY > FMB - Lecture 5 > Flashcards

FMB - Lecture 5 Flashcards

1
Q

Factors affecting the growth of bacteria:

A

Physical
- pH
- Temperature
- Oxygen concentration
- Moisture
- Hydrostatic pressure
- Osmotic pressure
- Radiation

Nutritional
- Carbon
- Nitrogen
- Sulfur
- Phosphorus
- Trace elements
- Vitamins

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1
Q

A measure of how acidic/basic water is.

A

pH

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2
Q

____ ranges from 0 to 14, with 7.0 being neutral.

A

pH

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3
Q

Acidity is inversely related to pH.

A
  • A system with high acidity has a low pH.
  • A system with low acidity has a high pH.
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4
Q

Most bacteria grow between pH _______.

A

pH 6.5 AND 7.5

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5
Q

Molds and yeast grow between pH _______.

A

pH 5 and 6

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6
Q

They grow in acidic enviroment.

A

Acidophiles

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7
Q

Examples of acidophiles.

A
  • Sulfolobus spp.
  • Lactobacillus spp.
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8
Q

Examples of neutrophiles.

A
  • Escherichia coli
  • Salmonella
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9
Q

They grow at a pH level of 7.0 - 11.5, 12.0

A

Alkaliphiles

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10
Q

Example of alkaliphiles.

A
  • Vibrio cholerae
  • Alcaligenes faecalis (9.0 - higher)
  • Agrobacterium (soil microorganisms, 12.0 pH)
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11
Q

Cause peptic ulcer.

A

Helicobacter pylori

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12
Q

_____ is neutrophile, however, its ability to survive low pH of the stomach would seem to suggest that it is an extreme acidophile.

A

H. pylori

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13
Q

The ammonium ion raises the pH of the immediate environment (NH4+ and CO2).

A

H. pylori

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14
Q

Effects of pH in growth of bacteria:

A
  1. Protection.
  2. Inhibits growth.
  3. Denaturation of enzymes and other proteins.
  4. Metabolic by-products.
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15
Q

It is a major environmental factor controlling microbial growth and is accomplished through enzymatic reactions.

A

Temperature

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16
Q

Because _____________ influences enzyme reactions, it has an important role in microbial growth in food.

A

Temperature

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17
Q

Must meet required environmental conditions.

A

Obligate

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18
Q

Adjust and tolerate / thrive in other environmental conditions, and can adapt.

A

Facultative

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19
Q

Cold loving microorganisms (cold temperature optima). Most extremes representative inhabit permanently in cold environments.

A

Psychrophiles

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20
Q

Growth temperature of 15 - 20 degree celsius and 0 - 20 degree celsius.

A

Psychrophiles

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21
Q

Example of obligate psychrophiles.

A

Bacillus globisporus - 20 degree celsius.

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22
Q

Example of facultative psychrophiles.

A

Xanthomonas pharmicola - below 20 degree celsius but can grow above 20 degree celsius.

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23
Q

Moderate loving microorganisms (midrange temperature optima). Found in warm-blooded animals and in terrestrial and aquatic environments in temperature and tropical latitudes.

A

Mesophiles

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24
Q

Growth temperature of 20 - 45 degree celsius / 25 - 40 degree celsius. Also considered as human pathogen because it grow best in human temperature (37 degree celsius).

A

Mesophiles

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25
Q

Growth temperature optima between 45 - 80 degree celsius / 50 - 60 degree celsius / 50 - 80 degree celsius.

A

Thermophiles

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26
Q

It can be seen in compost pits and hot springs. They are also called as heat loving microorganisms.

A

Thermophiles

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27
Q

Obligate thermophiles temperature:

A

Above 37 degree celsius

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28
Q

Facultative thermophiles temperature:

A

Both above and below 37 degree celsius.

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29
Q

Example of thermophiles.

A

Bacillus stearothermophilus

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30
Q

Optima greater than 80 degree celcius. These organisms inhabit hot environments including boiling hot springs, as well as undersea hydrothermal vents that can have temperature in excess of 100 degree celcius.

A

Hyperthermophiles

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31
Q

Example of hyperthermophiles:

A

Thermus aquaticus

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32
Q

Live as mesophiles but can live at a higher temperature for a short period of time.

A

Thermoduric

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33
Q

Growth temperature of 0 - 30 degree celcius. Cannot grow in 4. degree celcius. Low temperature food spoilage.

A

Psychrotrophs

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34
Q

Three cardinal temperature.

A
  1. Minimum Temperature
  2. Optimum Temperature
  3. Maximum Temperature
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35
Q

Temperature below which growth ceases, or lowest temperature at which microbes will grow.

A

Minimum Temperature

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36
Q

Temperature at which its growth rate is the fastest.

A

Optimum Temperature

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37
Q

Temperature above which growth ceases, or highest temperature at which microbes will grow.

A

Maximum Temperature

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38
Q

Effects of temperature in growth of bacteria:

A
  1. Enzyme activity.
  2. Preventing growth.
  3. Preservations
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39
Q

Microbes that use molecular oxygen produce more energy from nutrients

A

Aerobes (Oxygen)

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40
Q

Microbes that do not use oxygen.

A

Anaerobes (Oxygen)

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41
Q

Require an atmosphere oxygen in concentrations comparable to 20%–21%.

A

Obligate aerobes

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42
Q

Example of Obligate aerobes:

A

Pseudomonas

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43
Q

Not require oxygen for life and reproduction.

A

Obligate anaerobes

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44
Q

Example of Obligate anaerobes:

A

Clostridium botulinum

45
Q

They prefer an atmosphere containing about 5% oxygen.

A

Microaerophilic aerobes

46
Q

Examples of Microaerophilic aerobes:

A

Campylobacter

47
Q

They are capable of surviving in either the presence or absence of oxygen.

A

Facultative anaerobes

48
Q

Examples of Facultative anaerobes:

A

Staphylococcus, E. coli

49
Q

Does not require oxygen, grows better in the absence of oxygen, but can survive in O2 atmospheres.

A

Aerotolerant anaerobes

50
Q

Example of Aerotolerant anaerobes:

A

Lactobacillus

51
Q

They grow best in the presence of increased concentrations of CO2 (usually 5 to 10%)

A

Capnophilic organisms

52
Q

Microorganisms obtain almost all their nutrients in solution from the surrounding water.

53
Q

Require water for growth, and their composition is 80- 90% water.

54
Q

Most foods have a water activity above 0.95 and that will provide sufficient moisture to support the growth of bacteria, yeasts, and mold.

The amount of available moisture can be reduced to a point which will inhibit the growth of the organisms.

A

Water Activity

55
Q

Each microbial species (or group) has an optimum, maximum, and minimum AW level for growth.

A
  • most molds –0.8, with xerophilic molds as low as 0.6
  • most yeasts, 0.85, with osmophilic yeasts, 0.6–0.7
  • most Gram-positive bacteria, 0.90
  • Gram-negative bacteria, 0.93
56
Q

Organisms which thrive in high pressure

A

Barophiles (Hydrostatic pressure)

57
Q

Organisms which tolerate high pressure

A

Barotolerant (Hydrostatic pressure)

58
Q

Organisms which thrive in high solute

A

Osmophiles (Osmotic pressure)

59
Q

Organisms which tolerate high solute

A

Osmotolerant (Osmotic pressure)

60
Q

Organisms which thrive in high salt

A

Extreme halophiles (Osmotic pressure)

61
Q

(Osmotic pressure) At least 30% of salt concentration to live.

A

Obligate Halophiles

62
Q

(Osmotic pressure) From 2% and can tolerate up to 15% salt concentration.

A

Facultative Halophiles

63
Q

Organisms which tolerate high salt

A

Halotolerant

64
Q

Some microorganisms have pigments that screen ___________ and help to prevent DNA damage.

65
Q

Enzyme systems that can repair certain kinds of DNA damage.

66
Q

Nutritional Factors:

A
  • Carbon
  • Nitrogen
  • Sulfur
  • Phosphorus
  • Trace elements
  • Vitamins
67
Q

(Nutrient Content) Required by all organisms, necessary to support life.

A

carbohydrates
proteins
lipids
minerals
vitamins

68
Q

Elements required in fairly large amounts.

A

Macronutrients

69
Q

Macronutrients

A

Carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, sulfur, calcium, iron, sodium, chlorine, magnesium and a few other elements.

70
Q

Metals and organic compounds needed in very small amounts.

A

Micronutrients

71
Q

Micronutrients

A

Mn, Co, Zn, Cu, Ni and Mo.

72
Q

The structural backbone of living matter.

73
Q

It is needed for all the organic compounds that make up a living cell.

74
Q

Source of cellular energy (ATP or related compounds) to drive metabolic reactions.

75
Q

Half the dry weight of a typical bacterial
cell is ___________.

76
Q

All organisms, including microorganisms, need this to synthesize enzymes, other proteins, and nucleic acids.

77
Q
  • In amino acids, vitamins: thiamine, biotin
  • Most bacteria decompose proteins
  • Some bacteria use SO4 2- or H2S
78
Q
  • In DNA, RNA, ATP, and membranes
  • PO4 3- is a source of phosphorus
A

Phosphorus

79
Q

Very little amount is needed but critical to cell function. Often used as enzyme cofactors.

A

Micronutrients (Trace elements)

80
Q

It plays a major role in cellular respiration, being a key component of cytochromes and iron sulfur proteins involved in electron transport.

81
Q

Iron-binding agents that cells produce to obtain iron from various insoluble minerals.

A

Siderophores

82
Q

Organic compounds which are required in very small amount. Used as coenzyme.

83
Q

Some microorganisms tend to create their own ______.

Example: E. coli - is producing vitamin A in the body for blood clothing factor.

84
Q

Factors affecting the growth of fungi:

A
  1. Environmental Factors
  2. Chemical Factors
  3. Biological Factors
85
Q

Environmental Factors

A
  1. pH
  2. Temperature
  3. Atmospheric gases
  4. Photoperiod, light intensity
86
Q

Chemical Factors

A
  1. Type of substrate
  2. Antifungal agents
87
Q

Biological Factors

A
  1. Competing microflora
  2. Inoculum size
  3. Strain variability
88
Q

Temperature:

  • Psychrotolerant
  • Psychrophilic
  • Mesophilic
  • Thermotolerant
  • Thermophilic
A
  • Psychrotolerant – growth above 20 °C
  • Psychrophilic – maximum of 20 °C or below
  • Mesophilic - growth between 25 and 30.
  • Thermotolerant – growth at 30 to 45 °C
  • Thermophilic – growth above 45 °C
89
Q

Fungi have a wide range of acid/alkaline needs for growth, ranging from pH 3.0 to more than pH 8.0, with an ideal pH of approximately pH 5.0.

A

Hydrogen Ion concentration / pH

90
Q
  • Almost all molds. (Food spoilage molds)
  • Colonize the surface of the food (most oxygen demanding)
  • Inside the food (less demand for oxygen)
A

Obligate aerobes (Availability of oxygen)

91
Q

Most fungi are _________

A

obligate aerobes

92
Q

Most yeasts are __________

A

Facultative anaerobes

93
Q

MOISTURE LEVEL

A
  • If there are no cold-condensing surfaces and the relative humidity (RH) is maintained below 60 %indoors, there will not be enough water in those materials for mold to grow.
  • However, if the RH stays above 70% indoors for extended periods of time, mold will almost certainly grow.
  • Fungi need water for all stages of life or RH of >90%.
  • Normal yeasts require a minimum water activity of 0.85 or a RH of 88%.
94
Q

__________ are the most common osmophilic microorganisms.

A

Yeast

  • usually the cause of spoilage of high-sugar foods, including jams, molasses, corn syrup, flavored syrups and toppings, honey, concentrated fruit juices, chocolate candy with soft centers.
95
Q

__________ are more resistant to osmotic pressures.

A

Fungi

  • production of osmoprotectant compounds such as glycerol, reorganization of the cytoskeleton, and cell wall biogenesis.
  • NaCl
96
Q

__________ grow optimally in low light conditions.

A

Fungi

  • Many molds flourish in dark spaces but some prefer an alternate light pattern – some light, and some dark.
97
Q

___________ do not need sunlight to grow.

A

Yeast

  • Many molds flourish in dark spaces but some prefer an alternate light pattern – some light, and some dark.
98
Q

Types of Fungi:

A
  1. Field Fungi
  2. Storage Fungi
  3. Advanced Deterioration Fungi
99
Q

Invade crops while it’s still on the field (pre-harvest). High requirements of water.

A

Field Fungi

100
Q

Examples of field fungi:

A

Fusarium, some Aspergillus, Alternaria and Cladosporium

101
Q

Lower requirement of humidity. Presence before harvest but multiply during storage period.

A

Storage fungi

102
Q

Examples of storage fungi:

A

Aspergillus and Penicillium

103
Q

Easily attack damaged one and require high moisture content.

A

Advanced Deterioration Fungi

104
Q

Examples of advanced deterioration fungi:

A

A. clavatus, A. fumigatus, Rhizopus, and Mucor

105
Q

Presence of different microorganisms. Biological pest control agents.

A

Competing Microflora

106
Q

(Biological Factors) Trichoderma harzianum produces a lytic enzyme _______.

107
Q

Production of mycotoxins is influenced by both genotype (strain) and the environment.

A

Strain Variability

108
Q

Mostly found in soil. Spores, Sclerotia, or fragments of mycelium.

109
Q

NUTRITIONAL FACTORS

A
  • Use of Carbon source to fill their carbon needs for the synthesis of macromolecules.
  • Oxidation of sugars, alcohols, proteins, lipids, and polysaccharides for their source of energy.
  • Fungi requires source of nitrogen for synthesis of amino acids to proteins
  • Other MAJOR nutrients are sulfur, phosphorus, magnesium, and potassium which can be supplied to most fungi as salts.
  • TRACE elements like iron, copper, manganese, zinc, and molybdenum are required by nearly all fungi as cofactors for enzymes.
  • High amounts of trace elements can become toxic for some fungi.
110
Q

ADAPTATION TO LIMITED NUTRIENTS

A
  1. By increasing the quantities of enzymes that they produce.
  2. By making enzymes to metabolize another available nutrient.
  3. By adjusting their metabolic activities to grow at a rate
    consistent with availability of nutrients.

FOOD TECHNOLOGY (9 decks)

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