[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2006]
From the U.S. Government Printing Office via GPO Access
TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN
PART 173_SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN
CONSUMPTION--Table of Contents
Subpart D_Specific Usage Additives
Sec. 173.350 Combustion product gas.
The food additive combustion product gas may be safely used in the
processing and packaging of the foods designated in paragraph (c) of
this section for the purpose of removing and displacing oxygen in
accordance with the following prescribed conditions:
(a) The food additive is manufactured by the controlled combustion
in air of butane, propane, or natural gas. The combustion equipment
shall be provided with an absorption-type filter capable of removing
possible toxic impurities, through which all gas used in the treatment
of food shall pass; and with suitable controls to insure that any
combustion products failing to meet the specifications provided in this
section will be prevented from reaching the food being treated.
(b) The food additive meets the following specifications:
(1) Carbon monoxide content not to exceed 4.5 percent by volume.
(2) The ultraviolet absorbance in isooctane solution in the range
255 millimicrons to 310 millimicrons not to exceed one-third of the
standard reference absorbance when tested as described in paragraph (e)
of this section.
(c) It is used or intended for use to displace or remove oxygen in
the processing, storage, or packaging of beverage products and other
food, except fresh meats.
(d) To assure safe use of the additive in addition to the other
information required by the act, the label or labeling of the combustion
device shall bear adequate directions for use to provide a combustion
product gas that complies
with the limitations prescribed in paragraph (b) of this section,
including instructions to assure proper filtration.
(e) The food additive is tested for compliance with paragraph (b)(2)
by the following empirical method:
Spectrophotometric measurements. All measurements are made in an
ultraviolet spectrophotometer in optical cells of 5 centimeters in
length, and in the range of 255 millimicrons to 310 millimicrons, under
the same instrumental conditions. The standard reference absorbance is
the absorbance at 275 millimicrons of a standard reference solution of
naphthalene (National Bureau of Standards Material No. 577 or equivalent
in purity) containing a concentration of 1.4 milligrams per liter in
purified isooctane, measured against isooctane of the same spectral
purity in 5-centimeter cells. (This absorbance will be approximately
Solvent. The solvent used is pure grade isooctane having an
ultraviolet absorbance not to exceed 0.05 measured against distilled
water as a reference. Upon passage of purified inert gas through some
isooctane under the identical conditions of the test, a lowering of the
absorbance value has been observed. The absorbance of isooctane to be
used in this procedure shall not be more than 0.02 lower in the range
255 millimicrons to 310 millimicrons, inclusive, than that of the
untreated solvent as measured in a 5-centimeter cell. If necessary to
obtain the prescribed purities, the isooctane may be passed through
activated silica gel.
Apparatus. To assure reproducible results, the additive is passed
into the isooctane solution through a gas-absorption train consisting of
the following components and necessary connections:
1. A gas flow meter with a range up to 30 liters per hour provided
with a constant differential relay or other device to maintain a
constant flow rate independent of the input pressure.
2. An absorption apparatus consisting of an inlet gas dispersion
tube inserted to the bottom of a covered cylindrical vessel with a
suitable outlet on the vessel for effluent gas. The dimensions and
arrangement of tube and vessel are such that the inlet tube introduces
the gas at a point not above 5\1/4\ inches below the surface of the
solvent through a sintered glass outlet. The dimensions of the vessel
are such, and both inlet and vessel are so designed, that the gas can be
bubbled through 60 milliliters of isooctane solvent at a rate up to 30
liters per hour without mechanical loss of solvent. The level
corresponding to 60 milliliters should be marked on the vessel.
3. A cooling bath containing crushed ice and water to permit
immersion of the absorption vessel at least to the solvent level mark.
Caution. The various parts of the absorption train must be connected
by gas-tight tubing and joints composed of materials which will neither
remove components from nor add components to the gas stream. The gas
source is connected in series to the flow-rate device, the flow meter,
and the absorption apparatus in that order. Ventilation should be
provided for the effluent gases which may contain carbon monoxide.
Sampling procedure. Immerse the gas-absorption apparatus containing
60 milliliters of isooctane in the coolant bath so that the solvent is
completely immersed. Cool for at least 15 minutes and then pass 120
liters of the test gas through the absorption train at a rate of 30
liters per hour or less. Maintain the coolant bath at 0 [deg]C
throughout. Remove the absorption vessel from the bath, disconnect, and
warm to room temperature. Add isooctane to bring the contents of the
absorption vessel to 60 milliliters, and mix. Determine the absorbance
of the solution in the 5-centimeter cell in the range 255 millimicrons
to 310 millimicrons, inclusive, compared to isooctane. The absorbance of
the solution of combustion product gas shall not exceed that of the
isooctane solvent at any wavelength in the specified range by more than
one-third of the standard reference absorbance.
Additives that reference this regulation: