Food Chemistry

18.1 Fruits 843

(18.41)

18.1.2.8 Minerals

Table 18.34 gives the composition of the ash
of orange juice and apples. The most important

cation is potassium and the most important
inorganic anion is phosphate.

18.1.3 Chemical Changes During Ripening
of Fruit

Ripening of fruit involves highly complex
changes in physical and chemical properties.

Table 18.34.Minerals in fruit

Element Orange juice Apple

(% in ash) (mg/100g dry matter)

Potassium 40 840

Sodium 0. 37. 9

Calcium 2. 838

Magnesium 3.0 40

Iron 0. 06 1. 6

Aluminium 0. 12 0. 43

Phosphorus 3.8 73

Sulfur 0. 8

Chlorine 1. 0

Zinc, titanium, barium, Zinc 0. 65

copper, manganese, tin ≤ 0 .03 Manganese 0. 3

Boron ≤ 0 .01 Copper 0. 35

Softening, increasing sweetness, aroma and

color changes are among the most striking

phenomena related to ripening. Some changes

will be outlined below in more detail.

18.1.3.1 Changes in Respiration Rate

The respiration rate is affected by the develop-

ment stage of the fruit. A rise in respiration rate

occurs with growth. This is followed by a slow

decrease in respiration rate until the fruit is fully

ripe. In a number of fruits ripening is associated

with a renewed rise in respiration rate, which is

often denoted as a climacteric rise. Maximal CO 2

production occurs in the climacteric stage. De-

Fig. 18.8.Respiration rise in apples, Bramsley’s

seedlings (according toHulme, 1963.) A, apple picked

→, B, left on tree to ripen