Food Spoilage - Enzyme Action Flashcards

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1
Q

What are enzymes?

A

Protein catalysts that speed up chemical reactions without being destroyed or changed

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2
Q

Name one place where enzymes are naturally present?

A

Food

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3
Q

What do enzymes in food bring about?

A

Ripening of food
Browning of food/enzymic browning
Enzymic deterioration

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4
Q

What is spoilage caused by enzymes called?

A

Enzymic spoilage

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5
Q

What happens to the taste of fruit or veg as enzymes bring about their ripening?

A

Sweetness improves as the high starch content converts into sugars such as fructose

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6
Q

What happens to the colour of fruit or veg as enzymes bring about their ripening?

A

A colour change takes place such as tomatoes changing from green to red

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7
Q

What happens to the texture of fruit or veg as enzymes bring about their ripening?

A

A texture change takes place such as bananas changing from hard to soft and easily digestible

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8
Q

When do enzymes stop ripening fruit and veg?

A

Enzymes will continue to work even after the food has ripened

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9
Q

What happens when enzymes continue to work after a fruit or veg has ripened?

A

The enzymes will bring about the overripening of the food and will bring about the decay and decomposition of food

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10
Q

What happens to some fruit and vegetables when they are cut?

A

They will turn brown

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11
Q

Why do fruits such as apples turn brown when cut?

A

An enzyme called oxidase is released from their cell walls which oxidises

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12
Q

What happens to fruits and veg when their enzyme oxidase has oxidised?

A

They will turn brown and will eventually spoil

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13
Q

The oxidisation of oxidase does what to the quantity of Vitamin C in fruits and veg?

A

Reduces the amount of Vitamin C available

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14
Q

The oxidisation of oxidase reduces the quantity of what vitamin in fruit and veg?

A

Vitamin C

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15
Q

What do fish naturally contain which speeds up the spoilage and deterioration of their flesh even at low temperatures?

A

Enzymes

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16
Q

What do the enzymes naturally present in fish do even at low temperatures

A

They bring about the spoilage and deterioration of the fish’s flesh

17
Q

What is released when a fish’s flesh deteriorates by enzymes?

A

A putrid odour

18
Q

What five factors can control enzymic spoilage?

A
Acids
Heat
Additives (Preservatives) 
Cold Temperatures 
Blanching
19
Q

How do acids control enzymic spoilage?

A

Acids lower pH levels which inactivates enzymes which work best at neutral pHs

20
Q

How does heat control enzymic spoilage?

A

Enzymes are sensitive to high temperatures and are inactivated by cooking

21
Q

How do additives/preservatives control enzymic spoilage?

A

Sulfur dioxide is a preservative which inactivates enzymes and is used commercially to prevent enzymic spoilage

22
Q

How do cold temperatures control enzymic spoilage?

A

Low temperatures slow down enzyme activity in food, reducing the rate of spoilage and lengthening shelf life

23
Q

How does blanching control enzymic spoilage?

A

Blanching involves immersing vegetables in boiling water for five minutes and to destroy enzymes and then plunging them in ice cold water before freezing to prevent cooking