Week 4 : Alchemy in the kitchen Flashcards

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1
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

What are the 3 types of heat transfer in cooking and explain.

A
  1. Conduction : heat passing by direct contact between 2 materials
  2. Convection : Heat passes via movement of a heated material (water/air) against a colder material (e.g. when boiling, heat is transferred from hot water to food

3, Radiation : Heat transferred by electromagnetic radiation

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2
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

What are the 2 main importance of having heat transfer in food?

A
  1. Denaturation of proteins to affect texture (softer texture, more tender)
  2. Malillard reaction – impacts flavour, aroma, odour
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3
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

Changes in shapes of proteins can affect their taste and texture. True or False?

A

True

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4
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

define the Maillard reaction (4 key points)

A

A form of non-enzymatic browning that is initiated by a chemical reaction between a reducing sugar and an amino acid, upon the addition of heat.

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5
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

Maillard reaction involves a series of simultaneous and consecutive chemical reactions with intermediate products. True or False?

A

True

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6
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

Further flavour compounds arise from further interactions between the Maillard reaction and ___ (process)?

A

Thermal degradation of lipids

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7
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

How does Maillard reaction contribute to the browning on food?

A

Compounds, melanoidins are generated to contribute to brown colouration

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8
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

The Maillard reaction is always desirable in all food products. True or False?

A

False.

Flavours generated from Maillard reaction in products like fruit juice / milk are perceived as off-flavours.

Furthermore, the browning decreases product quality. Browning colour is undesirable in the products mentioned above too, and consumers may deem it to be unsafe for consumption.

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9
Q

[P1 : PHYSICS AND CHEMISTRY IN COOKING]

What are the 2 drawbacks of Maillard reaction in foods?

A
  1. Loss of nutrients –HEAT
    - amino acids are destroyed and protein quality decreases.
    - decreased bioavailability of amino acids and minerals (since AA bind w reducing sugars)
  2. Potentially harmful substances generated
    - e.g. Acrylamide in starch rich foods –> associated with cancer
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10
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

All microorganisms in food are harmful. True or False?

A

False, microbes in food (esp in fermented foods) are beneficial –> probiotics

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11
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are the 4 types of microbes that may be present in foods?

A
  1. Fermentation microbes – bacteria, yeasts, moulds
  2. Probiotics - mostly bacteria, promote health benefits
  3. Spoilage microbes – bacteria/moulds/yeasts that cause spilage
  4. Pathogens – mostly pathogenic bacteria and viruses causing food-borne illness/disease (food-poisoning)
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12
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

In food fermentation, beneficial microorganisms are intentionally introduced to influence which aspects of food?

A

Taste, aroma or nutritional quality

(technically shelf life too bc fermentation is a kind of preservation method)

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13
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are probiotics?

A

They are live microorganisms (mostly bacteria) when when administered in adequate amounts confer a health benefit on the host (human/animal) in terms of gut health or immunity

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14
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

Fermented foods are a well-known source of probiotics (e.g. yogurt). Are all MOs used in fermentation considered probiotics?

A

No, not all probiotics impact human health equally.

No, not all microbes used in fermentation are intended to be probiotics and might just be present to affect sensory qualities etc

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15
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

List a possible reason as to why not all fermented food contain probiotics ( when they are fermented by live bacteria)

A

These products go through additional processing which kill these live microbes

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16
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are prebiotics?

Most prebiotics are what kind of macronutrient?

A

Non digestible substances that provide a beneficial effect on host by selectively stimulating growth of probiotic bacteria.

Most prebiotics are carbohydrates (bacteria <3 glucose as carbon source)

17
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are synbiotics?

Note : NOT SYMBIOTIC!!

A

They are preparations of probiotics + prebiotics to deliver the potentially best health effect

synergy

18
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What is the difference between the growth of microbes in rotten vs fermented foods?

A

In food rot, the microbes grow uncontrollably

In fermentation, the choice of MO and fermentation conditions are carefully designed and controlled.

19
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What is the difference between food spoilage and food rot?

A

Food spoilage may occur due to non-microbial means (doesn’t mean it is unsafe to eat but high chance that it is unsafe), while food rot is spoilage due to microbes (definitely unsafe to eat)

20
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are the 4 types of food spoilage and is there a safety issue posed for each type of spoilage?

A
  1. Microbial spoilage – potential safety risk
  2. Chemical spoilage – no safety risk (e.g. oxidation/off-odour)
  3. Biochemical spoilage – no safety issues (enzymatic reactions, discolouration etc)
  4. Physical spoilage – no safety issue (e.g. Whey separation in yogurt)
21
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

Spoiled food is definitely unsafe for consumption. True or False?

A

False.
– if its not microbial spoilage then its still safe for consumption

22
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

Unsafe spoiled food will look, smell and taste spoiled. True or False.

A

False, unsafe spoilt food may not show any signs of physical/chemical spoilage (e.g. off odours/discolouration)

The food could look perfectly normal

23
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What is food infection and how can it be prevented?

A

The ingestion of foods containing pathogens.

Prevented by proper cooking as most microbes are destroyed by heat.

24
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What is food intoxication and how can it be prevented?

A

It is the ingestion of foods containing microbial toxins (the pathogens may be dead alr)

May not be preventable as some toxins are heat-resistant

25
Q

[PT 2 : MICROBIAL SYSTEMS IN FOOD]

What are some general prevention strategies for food poisoning?

A

Have good personal hygiene, food handling practices and cook food sufficiently

i.e. ensure no contamination by ensuring hygeine + cook food @ high enough temp for sufficient amount of time