The materiel administrator of the Department of Administrative Services shall purchase all necessary supplies for the institutions under the Department of Health and Human Services and the Department of Correctional Services, except, in its discretion, fresh fruit, vegetables, and emergency and minor purchases. The last-named supplies may be purchased by the chief executive officer or steward under the order of the department. An itemized statement of such purchases, duly verified, shall be filed with the department on the first day of each month. Estimates of needed supplies shall be furnished the department by each chief executive officer. Such estimates shall be examined by the department, and an itemized statement of such as are approved by the department, showing kind, quantity, and quality, shall be filed with the materiel administrator, and upon request shall be furnished to any applicant therefor.