2009_Book_FoodChemistry

18.1 Fruits 843
Table 18.34. Minerals in fruit
Element Orange juice Apple
(% in ash) (mg/100g dry matter)
Potassium 40 840
Sodium 0.3 7.9
Calcium 2.8 38
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
(18.41)
The respiration rate is affected by the development
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-
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.
Fig. 18.8. Respiration rise in apples, Bramsley’s
seedlings (according to Hulme, 1963.) A, apple picked
→, B, left on tree to ripen