Inter-Relations of Hesperidin,Some other Natural Components and Certain Enzyme Systems in Developing Shamouti Orange Fruits

The relationships of a large number of components and enzyme systems of the Shamouti orange fruit have been studied during the growth period extending from April to December. Data have been evaluated with the help of an electronic computer.

Early in July, towards the end of the first period of growth, peel thickness attains its maximum, cell divisions almost cease, growth of internal fruit parts (endocarp) begins and many fruit components (as ascorbic and dehydroascorbic acids and the bioflavanoid hesperidin) and many enzymic systems (as peroxidase, catalase, indole acetic acid oxidase and ascorbic acid oxidase) attain their maximum values and activities when expressed on a total nitrogen basis. This points to higher metabolic activity of tissues during the first period of growth.

During the second period (July to December) concentrations and activities of components decrease, relative to fresh and dry weight and to total nitrogen, partly because of dilution by inert cellular components and partly through decreasing metabolic activity. Only by expressing results on a per fruit basis (because of the large increase in volume of individual fruits) do the values of some components, especially reducing sugars and catalase activity, continue to increase.

The ascorbic acid system, hesperidin, and enzymes effective in oxidation of ascorbic acid, in degradation of the growth hormone indole-3-acetic acid and otherwise active in oxido-reduction reactions are interrelated' both when the curves are compared and after the time effect has been removed. This suggests that these systems are interrelated irrespective of the age of the fruit.