All revenues in excess of all obligations of the authority, of every nature, which are not otherwise pledged or restricted as to disposition and use by the terms of any trust indenture entered into by the authority for the security of bonds issued under this article, together with all receipts and gifts of every kind and nature whatsoever, shall constitute the authority fund. The authority, in its discretion, shall pledge or utilize the authority fund for any one or more of the following purposes:

(1) Pledges to the payment of any bond issue requirements or sinking or reserve funds, as may be provided for under this article;

(2) Payment of any outstanding unpaid bond obligations or administrative expenses;

(3) Construction of any project requested by the Commissioner of Agriculture, the cost of which amounts to a sum less than the accumulated balance of such fund;

(4) The most advantageous obtainable purchase, redemption, and retirement of the authority's bonds, pursuant to privileges accorded to the authority in the various issues of bonds outstanding; or

(5) Investment in obligations of the United States or obligations the payment of which is guaranteed by the United States, of guaranteed convertibility or maturity not in excess of five years, provided that funds so invested and income from such investments shall always be available to and ultimately expended for other purposes set forth in this Code section.