STRUCTURE AND COMPOSITION
The freshly fruits of commerce comprise various combinations
of tissues that may include an expanded ovary, the seed, and other plant parts such as the receptacle (e.g. apple, strawberry, cashew apple), bract and peduncle (e.g. pineapple). This combination of tissues gives us an organ defined by the Shorter Oxford Dictionary as ‘the edible product of a plant or tree, consisting of the seed and its envelope, especially the latter when juicy and pulpy’. A consumer definition of fruit would be ‘plant products with aromatic flavours, which are either naturally sweet or normally sweetened before eating’; they are essentially dessert foods.
CELLULAR COMPONENT
The cells of
fruit and vegetables are typical plant cells. Plant cell are bounded by a more or less rigid cell wall composed of cellulose fibres, and other polymers such as pectic substances, hemicelluloses, lignin’s and proteins. A layer of pectic substances forms the middle lamella and acts to bind adjacent cells together. Adjacent cells often have small communication channels, called plasmadesmata, linking their cytoplasmic masses. The cell wall is permeable to water and solutes.
The main functions of the wall are to:
- Contain the cell content by supporting the outer cell membrane, the plasma lemma, against the hydrostatic pressures of the cell contents, which would otherwise burst the membrane; and
- Give structural support to the cell and the plant tissues
STRUCTURE AND COMPOSITION