Transport and Storage

Fruits and vegetables are live after they have been harvested. They continue to respire giving off carbon dioxide, moisture and heat. This influences how they are transported and stored, as well as packaging and refrigeration requirements. Internal activities of fruits and vegetables after harvest include changes in carbohydrates, pectins, organic acids, and the effects these have on various quality attributes of the produce.

Changes in carbohydrates are variable. In some plant products sugars quickly decrease and starch increases in amount soon after harvest (eg ripe sweet corn can suffer flavour and texture quality losses in a very few hours after harvest). In contrast, unripe fruit is frequently high in starch and low in sugars. Temperature affects the changes in carbohydrates.

Fruit and vegetable nutrients have varying sensitivity and stability during the phases of food acquisition, processing, storage, and preparation. The table below taken from Harris and Karmas, 1975 provides an example.

TABLE Specific sensitivity and stability of nutrients*

Nutrient

Neutral pH 7

Acid < pH 7

Alkaline > pH 7

Air or Oxygen

Light

Heat

Cooking Losses, Range

Vitamins

Vitamin A

S

U

S

U

U

U

0-40

Ascorbic

U

S

U

U

U

U

0-100

acid(C)

 

Biotin

S

S

S

S

S

U

0-60

Carotenes

S

U

S

U

U

U

0-30

(pro A)

 

 

 

 

 

 

0-5

Choline

S

S

S

U

S

S

0-10

Cobalamin

S

S

S

U

U

S

 

(B12)

 

 

 

 

 

 

0-40

Vitamin D

S

 

U

U

U

U

0-10

Essential

S

S

U

U

U

S

 

fatty acids

 

Folic acid

U

U

S

U

U

U

0-100

Inositol

S

S

S

S

S

U

0-95

Vitamin K

S

U

U

S

U

S

0-5

Niacin (PP)

S

S

S

S

S

S

0-75

Pantbothenic

S

U

U

S

S

U

0-50

acid

 

p-Amino

S

S

S

U

S

S

0-5

Benzoic acid

 

 

 

 

 

 

 

Vitamin B6

S

S

S

S

U

U

0-40

Riboflavin

S

S

U

S

U

U

0-75

(B2)

 

Tbiamin (B1)

U

S

U

U

S

U

0-80

Tocopherols

S

S

S

U

U

U

0-55

(U = Unstable; S = Stable)

This table illustrates the sensitivity and stability of vitamins, essential amino acids, and minerals to acid, air, light, and heat. These are factors that cannot be fully controlled during transport and storage. This information also provides an indication of what happens during cooking.

The ultimate nutritive value of a food results from the sum total of losses incurred throughout its history - from germination to consumer.