i. The food value of carbohydrates in the diet are:
a. Provide heat and energy
b. Necessary in the diet to burn fat
c. The roughage provides assistance to keep the digestive tract healthy.
ii. Cooking effects on carbohydrate:
a. Starch: moist heat on starch causes the starch grains to soften and swell. Near boiling point the cellulose framework bursts, releasing the starch, which thickens the liquid. Dry heat causes the starch to change colour from creamy white to brown and after prolonged heat will carbonized and burn. Water is given off during heating and the starch on the surface is changed to dextrin, a form of sugar, as in toast.
b. Sugar: moist heat causes sugar to dissolve in water more rapidly in hot water than in cold. On heating it becomes syrup; on further heating it colours then caramelizes and will eventually turn to carbon and ash.
c. Cellulose: cellulose is not water-soluble and is not affected much by cooking. Pectins which holds the cell walls can be particularly dissolved by hot water. This is exactly what happens when vegetables are cooked and responsible for the softer texture of cooked vegetables and fruit
