Section 184.1240 - Carbon dioxide(a) Carbon dioxide (empirical formula CO2, CAS Reg. No. 124-38-9) occurs as a colorless, odorless, noncombustible gas at normal temperatures and pressures. The solid form, dry ice, sublimes under atmospheric pressure at a temperature of -78.5 °C. Carbon dioxide is prepared as a byproduct of the manufacture of lime during the "burning" of limestone, from the combustion of carbonaceous material, from fermentation processes, and from gases found in certain natural springs and wells.(b) The ingredient must be of a purity suitable for its intended use.(c) In accordance with § 184.1(b)(1) , the ingredient is used in food with no limitations other than current good manufacturing practice. The affirmation of this ingredient as generally recognized as safe (GRAS) as a direct human food ingredient is based upon the following current good manufacturing practice conditions of use: (1) The ingredient is used as a leavening agent as defined in § 170.3(o)(17) of this chapter; a processing aid as defined in § 170.3(o)(24) of this chapter; and a propellant, aerating agent, and gas as defined in § 170.3(o)(25) of this chapter.(2) The ingredient is used in food at levels not to exceed current good manufacturing practice.(d) Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.48 FR 57270, Dec. 29, 1983, as amended at 73 FR 8607 , Feb. 14, 2008