Exhibit 32.1
CERTIFICATION OF
CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER
PURSUANT TO 18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
In connection with the Quarterly Report on Form 10-Q of Alto Ingredients, Inc. (the “Company”) for the period ended June 30, 2026 (the “Report”), the undersigned hereby certify in their capacities as Chief Executive Officer and Chief Financial Officer of the Company, respectively, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:
| 1. | the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and |
| 2. | the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. |
| Dated: August 7, 2026 | By: | /s/ BRYON T. MCGREGOR |
| Bryon T. McGregor | ||
| President and Chief Executive Officer | ||
| (Principal Executive Officer) | ||
| Dated: August 7, 2026 | By: | /s/ ROBERT R. OLANDER |
| Robert R. Olander | ||
| Chief Financial Officer | ||
| (Principal Financial and Accounting Officer) | ||
A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signatures that appear in typed form within the electronic version of this written statement required by Section 906, has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.
This certification is being furnished and not filed with the Securities and Exchange Commission pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section. This certification shall not be deemed to be incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, except to the extent that the registrant specifically incorporates it by reference.