Fruits and Vegetables

Question 1

What is the general composition of most fruits and vegetables?

Answer 1

High in water and carbohydrates and low in proteins and fats.

Question 2

What digestible carbohydrates are found fruits and vegetables?

Answer 2

sugars and starches

Question 3

What indigestible carbohydrates are found fruits and vegetables?

Answer 3

cellulose, hemicellulose, lignin, and pectic materials

Question 4

How do cell walls change during the aging process?

Answer 4

Cell walls are relatively thin at first composed of cellulose and held together by pectin. As cells age, the wall thickens and there is a higher amount of tough fibrous hemicellulose and lignins are formed.

Question 5

What are fruits and vegetables a good source of?

Answer 5

vitamins, minerals, natural sugars, organic acids, flavour compounds, and bioactive phytochemicals

Question 6

How do fruits and vegetable gain their colour?

Answer 6

From pigments such as anthocyanins (purple), carotenoids (orange), and chlorophylls (green)

Question 7

What does the correct time to harvest fruits and vegetables depend on?

Answer 7

The particular species and their use.

Question 8

What is the time lag between harvest and consumption for non-climacteric fruits such as grapes and strawberries?

Answer 8

They are harvested at a fully ripened state and consumed quickly.

Question 9

What is the time lag between harvest and consumption for climacteric fruit such as apples and bananas?

Answer 9

They are harvested when they are immature so they may ripen over time and be consumed later on.

Question 10

Describe the postharvest changes in fruits and vegetables and when they are edible.

Answer 10

Fruits and vegetables are not edible when they are immature and growing, when they are mature and ripe they are edible, and once they have reached senescence they are not edible.

Question 11

What does the growth phase of fruits and vegetables encompass?

Answer 11

Cell division and enlargement causing an increase in size.

Question 12

How can you tell when fruits and vegetables have reached maturation?

Answer 12

When they reach the end of their growth phase. It is exhibited through sweetness, softness, colour, and flavour development.

Question 13

What is the process of ripening?

Answer 13

What happens due to natural physiological processes under enzymatic and hormonal control (both physical and chemical changes).

Question 14

What is senescence?

Answer 14

The phase associated with the deteriorative process, caused by aging, tissue death, and associated with loss of quality.

Question 15

What is, and what major role does, ethylene play in ripening?

Answer 15

It is a plant hormone that plays a role in ripening and senescence. Its synthesis is stimulated by stressors. it breaks down chlorophyll, acids, amylase to starch and sugars, pectin (softening), and large organic molecules functioning in the aroma and tastes associated with ripe fruit.

Question 16

What is the effect of ethylene on climacteric fruits?

Answer 16

Large amounts are produced during ripening. External exposure speed up the ripening process

Question 17

What is the effect of ethylene on non-climacteric fruits?

Answer 17

Not ethylene is produced during the ripening process but when it is exposed to ethylene externally it can be a de-greening agent as it breaks down chlorophyll and expresses the carotenoid pigments. Fruits exposed to this will soften and increase their respiration rate.

Question 18

What is respiration in relation to fruit and vegetable?

Answer 18

A metabolic process by which cells convert energy from one type of chemical structure into another form.

Question 19

Describe the process of aerobic respiration.

Answer 19

Oxygen and glucose are consumed while carbon dioxide, water and heat are produced.

Question 20

Describe metabolic collapse in leafy crops.

Answer 20

Cell membranes break down allowing contents to leak out. Bacteria gives off-odour and there are visual symptoms of tissue collapse such as yellowing.

Question 21

How does temperature control effect ripening and respiration?

Answer 21

Increased warmth and moisture levels develop bacterial and fungal infections. Fruits may over-ripen a a faster rate if temperature is too high.

Question 22

How do water levels in produce effect the deterioration process?

Answer 22

If there is too much water loss from tissue wilting and shrivelling will occur.

Question 23

What does the speed of post-harvest water loss depend on?

Answer 23

external vapour pressure, products with a large surface to volume ratio, thickness of the fruit peel

Question 24

What are the most important microorganisms causing post-harvest wastage? Is this particularly true for fruits or vegetables and how do acidity levels affect loss?

Answer 24

Fungi, in particular fruits because the relatively acidic conditions suppress bacterial growth. Vegetables with a higher pH can suffer high losses from bacterial infections.

Question 25

What are adverse quality changes in fresh produce caused by?

Answer 25

metabolic disturbances, mineral imbalance, and non-optimal environmental factors.

Question 26

What is the most important cause of fresh produce?

Answer 26

Physical injury as a site for post-harvest pathogens, stimulating ethylene production in plant tissues and leading to premature ripening and yellowing.

Question 27

What are 4 factors contributing to produce deterioration?

Answer 27

1. Water loss
2. Fungal and bacteria growth
3. Physiological disorders
4. Physical Inury

Question 28

What are 5 ways that fresh produce can maintain its quality?

Answer 28

1. Precooling
2. Pre-storage treatments (surface coating and wraps as well as irradiation)
3. Controlled Atmosphere storage
4. Packaging
5. Modified atm packaging by polymeric films

Question 29

What is precooling used for in terms of produce?

Answer 29

Is used to remove field heat quickly after harvest and slow down deterioration of highly perishable products. This can be done through icing or hydrocooling.

Question 30

What is hydrocooling?

Answer 30

Many produce types can be cooled by bringing them into contact with flowing cold water.

Question 31

What is icing?

Answer 31

Use of the application of crushed ice to temporarily cool crops during transport (leafy green vegetables).

Question 32

What are 2 pre-storage treatments used to maintain quality of fresh produce?

Answer 32

1. Surface coatings and wraps

2. Irradiation

Question 33

What are surface coatings and wraps used for in terms of maintaining produce quality?

Answer 33

Slow down loss of water and remove O2 and CO2.

Question 34

What are many sruface coatings and wraps made from?

Answer 34

Carnuba or sugar cane waxes, polymers of sugar esters, petroleum based products

Question 35

What is irradiation and how is it used to maintain the quality of fresh produce?

Answer 35

The application of x-rays, y-rays, or high energy electrons to fresh produce to control fungal disease and increase storage potential. Not used often because of consumer concerns and legislation.

Question 36

What is controlled atmospheric storage?

Answer 36

Levels of O2 are reduced and levels of CO2 are raised to control respiration rates.

Question 37

How can packaging maintain produce freshness?

Answer 37

Conventional packaging may reduce physical damage to the produce.

Question 38

How do modified atmospheric packages by polymeric film maintain produce freshness?

Answer 38

Provide a barrier which protects and affects the movement of respiratory gases depending on it permeability. This can lower O2 and raise CO2 reducing the respiration and extending the shelf-life. They also maintain temperature.

Question 39

What types of modified atmospherica packaging are there?

Answer 39

Active and passive packaging.

Question 40

What is active modified packaging?

Answer 40

Involves a slight vacuum which replaces the atmosphere with the desired gas mixture.

Question 41

What is passive modified packaging?

Answer 41

The atmosphere is maintained through the respiration of the produce within the package.