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HDSO Food Science > Lecture 1 > Flashcards

Lecture 1 Flashcards

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1
Q

What are the 3 main microorganisms in food?

A

Mould
Bacteria
Yeast

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2
Q

What is yeast?

A 
One cell microorganisms
Reproduced by budding
Grow best in the presence of:
-moisture
-O2
-Sugar
-Acidic pH

Ferments sugar into alcohol and CO2

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3
Q

What food is yeas important in?

A

Bread
Wine
Beer

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4
Q

What is a mould?

A

Multicellular and filamentous
Reproduce by spores
Grow on dry food, cereals, grains (unique to them)
Can grow at room temp or cold temps

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5
Q

What food is mould important in?

A

Cheese and soy sauce

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6
Q

What are the different bacterial morphologies?

A 
Cocci
diplococci
Sarcina
Staphylcocci
Streptococci
Rods
Vibrio
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7
Q

What are 2 important factors that are important to microbial growth?

A

Extrinsic Factors

Intrinsic factors

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8
Q

What are extrinsic factors?

A

Depends ono the storage environment such as:

  • Temp
  • HUmidity
  • Envrionmental Gases(O2, CO2)
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9
Q

What are intrinsic factors?

A

Properties inherent to food to help protect them such as:

  • biological structure (skin, shell)
  • pH, water activity, anti-microbial compounds, nutrients
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10
Q

What are the 2 kinds of water activity?

A

Higher the free water the higher the water activity

○ Free water available for physical and chemical reactions
○ Bound water bound to sugars and not able to participate in andy chemical reactions

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11
Q

How can low water activity be brought about?

A

Dehydration

Addition of Salt or sugar (binds water to make in unavailable)

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12
Q

What water activity do most fresh foods have?

A

0.96-0.99

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13
Q

Bacteria that causes food-born illness will grow on foods that have a water activity of what?

A

0.85 and above

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14
Q

What are the 3 temp categories that bacteria like to grow at?

A

Psychrophilic Cold
Thermophilic >40C
Mesophilic ~30C

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15
Q

How do we classify bacteria based on their need for O2?

A

Aerobic or Microaerophile (likes small % of O2)
Anaerobic
Facultative (can grow in presence or absence of O2)

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16
Q

What are spore formers?

A

Bacteria form spores around themselves to protect against harsh environment

Can have dorment spores, activated in better conditions

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17
Q

In general what do molds require for growth?

A

O2

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18
Q

What conditions does yeast grow best in?

A

Aerobic

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19
Q

What is food spoilage?

A

Indicative of deterioration in taste, smell, sight and texture
-deterioration of sensory products

20
Q

How can spoilage occur?

A

Chemical reaction: oxidation of fats causes rancidity

Physical change: bruising/dehydration

Microbial growth

21
Q

What are the typical indications of food spoilage?

A 
Mold growth
Gas
Slime 
Off odour
Off Flavour
22
Q

What is the most common off odour ?

A

Smell of ammonia, sulphides and hydrogen sulphide

-typical smell of eggs

23
Q

What is the most common off flavour?

A

Acidic
Bitter
Not fresh

24
Q

What is the most common off texture?

A

Slimy

Mushy

25
Q

What are the heat propterties of E coli?

A

can grow/live in cold but is heat sensitive

26
Q

What is a toxin producing mold?

A

Aspergillus produces aflatoxin which can causes liver cancer

-common in peanut production

27
Q

Where do we mostly see viruses?

A

Cheese

Raw shellfish

28
Q

What is the most common parasite?

A

trichinella round worms

-typically found in pork

29
Q

What are the 5 main practices in food handling?

A
  1. People will communicable diseases and skin lesions should never handle foods
  2. When handling food, person must wear clean (white) clothing and head cover
  3. When handling foods, hands should not touch mouth, nose or any other part of the body
  4. When handling foods, person should not eat, drink smoke sneeze or cough
  5. Pets and other animals should be kept away from food processing area
30
Q

What is the danger zone?

A

4-60C

31
Q

What is bacterial growth rate?

A

Change in the #/time

32
Q

What is bacterial generation time?

A

Doubling time of the population size

33
Q

What is binary fission?

A

One cell divides into 2 cells

34
Q

What is the logistic growth rate of bacteria?

A

Lag phase
Log phase
Stationary phase
Death Phase

In reality how bacteria grow

35
Q

How does fermentation preserve food?

A

pH reduction
Alcohol production
O2 reduction
Microbial inhibitors

36
Q

Fermentation produces desirable changes in which characteristics of food?

A

Flavour
Texture
Nutritional Value

37
Q

What is the definition of fermentation?

A

Breakdown of Carbs to yield:

  • lactic acid
  • Alcohol
  • Acetic acid
  • CO2
38
Q

What is the difference between control fermentation and wild fermentation?

A

Control: We know the type of bacteria added and know what will happen.

Wild: you don’t know anything

39
Q

What is lactic acid fermentation?

A

Simple sugars to lactic acid

40
Q

What re the bacteria genera involved in fermentation?

A 
Lactococcus
Lactobacillus
Leuconooostoc (butter flavour)
Pediococcus
Streptococcus
41
Q

What food items are able to ferment?

A

Dairy: yogurt
Meat: cured sausage (salami)
Veg: pickles, sauerkraut, olives

42
Q

What its Koji fermentation?

A

For soy sauce

Aspergillus oryzae mold is added to beans to break down protein and carbs

Then lactobacillus is added to break down into simple sugars

Yeast is added to reduce the sugar to alcohol

43
Q

What is alcoholic fermentation?

A

Sugar is converted to CO2 and alcohol with saccharoomyces species
-anaerobic process

44
Q

Whiskey, brandies and gins are produced by distilling off what?

A

The alcohol from materials that have been fermented by yeast

45
Q

What is acetic acid fermentation?

A

Alcohol + OO2 gives water and acetic acid (vinegar)

46
Q

What is Coo2 fermentation?

A

Sucrose broken down into glucose and fructose which is further broken down into CO2 and alcohol with the use or Saccharomyces cereviisiiae

HDSO Food Science (17 decks)

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