The commissioner is authorized to receive complaints against any persons dealing in, shipping, transporting, storing, or selling produce, and shall have authority to make any and all necessary investigations relative to the handling of, or storing, shipping, or dealing in produce at wholesale and shall, at all times, have access to all buildings, yards, warehouses, storage and transportation facilities in which any produce is kept, stored, handled or transacted. For the purpose of enforcing the provisions of sections 27.01 to 27.14 and 27.19, the commissioner shall have the authority, upon complaint being filed for any alleged violation of the provisions thereof, or the rules issued thereunder, or upon information furnished by an inspector of the Department of Agriculture, to suspend while violation continues or revoke any license issued by the commissioner upon ten days notice to the licensee and an opportunity to be heard. Where the public interest requires it the commissioner may suspend a license after such notice pending hearing and decision. The commissioner shall have, and is hereby granted, full authority to issue subpoenas requiring the attendance of witnesses before the commissioner, with books, papers, and other documents, articles, or instruments, and to compel the disclosure by such witnesses of all facts known to them relative to the matter under investigation, and shall have full authority to administer oaths and to take testimony; and the commissioner shall thereafter give the complainant a written report of the investigation. Such report shall be prima facie evidence of the matters therein contained. All parties disobeying the orders or subpoenas of the commissioner shall be guilty of contempt as in proceedings in district courts of the state and may be punished in like manner.