[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR173.25]
[Page 122.126]
TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN
SERVICES (CONTINUED)
PART 173 SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN
Subpart A Polymer Substances and Polymer Adjuvants for Food Treatment
Sec. 173.25 Ion-exchange resins.
Ion-exchange resins may be safely used in the treatment of food
under the following prescribed conditions:
[[Page 123]]
(a) The ion-exchange resins are prepared in appropriate physical
form, and consist of one or more of the following:
(1) Sulfonated copolymer of styrene and divinylbenzene.
(2) Sulfonated anthracite coal meeting the requirements of ASTM
method D388-38, Class I, Group 2, ``Standard Specifications for
Classification of Coal by Rank,'' which is incorporated by reference.
Copies are available from University Microfilms International, 300 N.
Zeeb Rd., Ann Arbor, MI 48106, or available for inspection at the
National Archives and Records Administration (NARA). For information on
the availability of this material at NARA, call 202-741-6030, or go to:
http://www.archives.gov/federal--register/code--of--federal--
regulations/ibr--locations.html.
(3) Sulfite-modified cross-linked phenol-formaldehyde, with
modification resulting in sulfonic acid groups on side chains.
(4) Methacrylic acid-divinylbenzene copolymer.
(5) Cross-linked polystyrene, first chloromethylated then aminated
with trimethylamine, dimethylamine, di-ethylenetriamine, or
dimethylethanol-amine.
(6) Diethylenetriamine, triethylene-tetramine, or
tetraethylenepentamine cross-linked with epichlorohydrin.
(7) Cross-linked phenol-formaldehyde activated with one or both of
the following: Triethylene tetramine and tetraethylenepentamine.
(8) Reaction resin of formaldehyde, acetone, and
tetraethylenepentamine.
(9) Completely hydrolyzed copolymers of methyl acrylate and
divinylbenzene.
(10) Completely hydrolyzed terpolymers of methyl acrylate,
divinylbenzene, and acrylonitrile.
(11) Sulfonated terpolymers of styrene, divinylbenzene, and
acrylonitrile or methyl acrylate.
(12) Methyl acrylate-divinylbenzene copolymer containing not less
than 2 percent by weight of divinylbenzene, aminolyzed with
dimethylaminopro-pylamine.
(13) Methyl acrylate-divinylbenzene copolymer containing not less
than 3.5 percent by weight of divinylbenzene, aminolyzed with
dimethylaminopro-pylamine.
(14) Epichlorohydrin cross-linked with ammonia.
(15) Sulfonated tetrapolymer of styrene, divinylbenzene,
acrylonitrile, and methyl acrylate derived from a mixture of monomers
containing not more than a total of 2 percent by weight of acrylonitrile
and methyl acrylate.
(16) Methyl acrylate-divinyl benzene di ethylene glycol divinyl
ether terpolymer containing not less than 3.5 percent by weight of di
vinyl benzene and not more than 0.6 percent by weight of di ethylene
glycol divinyl ether, aminolyzed with di methyl amino propyl amine.
(17) Styrene-divinylbenzene cross-linked copolymer, first
chloromethylated then aminated with dimethylamine and oxidized with
hydrogen peroxide whereby the resin contains not more than 15 percent by
weight of vinyl N,N-di methyl benzyl amine-N-oxide and not more than 6.5
percent by weight of nitrogen.
(18) Methyl acrylate-divinylbenzene-diethylene glycol divinyl ether
terpolymer containing not less than 7 percent by weight of
divinylbenzene and not more than 2.3 percent by weight of diethylene
glycol divinyl ether, aminolyzed with di methyl amino propyl amine and
quaternized with methyl chloride.
(19) Epichlorohydrin cross-linked with ammonia and then quaternized
with methyl chloride to contain not more than 18 percent strong base
capacity by weight of total exchange capacity [Chemical Abstracts
Service name: Oxirane (chloromethyl)-, polymer with ammonia, reaction
product with chloromethane; CAS Reg. No. 68036-99-7].
(20) Regenerated cellulose, cross-linked and alkylated with epi
chloro hydrin and propylene oxide, then sulfonated whereby the amount of
epi chloro hydrin plus propylene oxide employed does not exceed 250
percent by weight of the starting quantity of cellulose.
(b) Ion-exchange resins are used in the purification of foods,
including potable water, to remove undesirable ions or to replace less
desirable ions with
[[Page 124]]
one or more of the following: bicarbonate, calcium, carbonate, chloride,
hydrogen, hydroxyl, magnesium, potassium, sodium, and sulfate except
that: The ion-exchange resin identified in paragraph (a)(12) of this
section is used only in accordance with paragraph (b)(1) of this
section, the ion-exchange resin identified in paragraph (a)(13) of this
section is used only in accordance with paragraph (b)(2) of this
section, the resin identified in paragraph (a)(16) of this section is
used only in accordance with paragraph (b)(1) or (b)(2) of this section,
the ion-exchange resin identified in paragraph (a)(17) of this section
is used only in accordance with paragraph (b)(3) of this section, the
ion-exchange resin identified in paragraph (a)(18) of this section is
used only in accordance with paragraph (b)(4) of this section, and the
ion-exchange resin identified in paragraph (a)(20) of this section is
used only in accordance with paragraphs (b)(5) and (d) of this section.
(1) The ion-exchange resins identified in paragraphs (a) (12) and
(16) of this section are used to treat water for use in the manufacture
of distilled alcoholic beverages, subject to the following conditions:
(i) The water is subjected to treatment through a mixed bed
consisting of one of the resins identified in paragraph (a) (12) or (16)
of this section and one of the strongly acidic cation-exchange resins in
the hydrogen form identified in paragraphs (a) (1), (2), and (11) of
this section; or
(ii) The water is first subjected to one of the resins identified in
paragraph (a) (12) or (16) of this section and is subsequently subjected
to treatment through a bed of activated carbon or one of the strongly
acidic cation-exchange resins in the hydrogen form identified in
paragraphs (a) (1), (2), and (11) of this section.
(iii) The temperature of the water passing through the resin beds
identified in paragraphs (b)(1) (i) and (ii) of this section is
maintained at 30 [deg]C or less, and the flow rate of the water passing
through the beds is not less than 2 gallons per cubic foot per minute.
(iv) The ion-exchange resins identified in paragraph (a) (12) or
(16) of this section are exempted from the requirements of paragraph
(c)(4) of this section, but the strongly acidic cation-exchange resins
referred to in paragraphs (b)(1) (i) and (ii) of this section used in
the process meet the requirements of paragraph (c)(4) of this section,
except for the exemption described in paragraph (d) of this section.
(2) The ion-exchange resins identified in paragraphs (a) (13) and
(16) of this section are used to treat water and aqueous food only of
the types identified under Categories I, II, and VI-B in table 1 of
Sec. 176.170(c) of this chapter: Provided, That the temperature of the
water or food passing through the resin beds is maintained at 50 [deg]C
or less and the flow rate of the water or food passing through the beds
is not less than 0.5 gallon per cubic foot per minute.
(i) The ion-exchange resin identified in paragraph (a)(13) of this
section is used to treat water and aqueous food only of the types
identified under categories I, II, and VI-B in Table 1 of Sec.
176.170(c) of this chapter: Provided, That the temperature of the water
or food passing through the resin bed is maintained at 50 [deg]C or less
and the flow rate of the water or food passing through the bed is not
less than 0.5 gallon per cubic foot per minute.
(ii) The ion-exchange resin identified in paragraph (a)(16) of this
section is used to treat water and aqueous food only of the types
identified under categories I, II, and VI-B in Table 1 of Sec.
176.170(c) of this chapter, Provided, that either:
(A) The temperature of the water or food passing through the resin
bed is maintained at 50 [deg]C or less and the flow rate of the water or
food passing through the bed is not less than 0.5 gallon per cubic foot
per minute; or
(B) Extracts of the resin will be found to contain no more than 1
milligram/kilogram dimethylaminopropylamine in each of the food
simulants, distilled water and 10 percent ethanol, when, following
washing and pretreatment of the resin in accordance with Sec.
173.25(c)(1), the resin is subjected to the following test under
conditions simulating the actual temperature and flow rate of use: ``The
Determination of 3-Dimethylaminopropylamine in Food Simulating Extracts
of Ion Exchange
[[Page 125]]
Resins,'' February 4, 1998, which is incorporated by reference in
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available
from the Division of Petition Control (HFS-215), Center for Food Safety
and Applied Nutrition, Food and Drug Administration, 5100 Paint Branch
Pkwy., College Park, MD 20740, or may be examined at the Center for Food
Safety and Applied Nutrition's Library, 5100 Paint Branch Pkwy., College
Park, MD 20740, or at the National Archives and Records Administration
(NARA). For information on the availability of this material at NARA,
call 202-741-6030, or go to: http://www.archives.gov/federal--register/
code--of--federal--regulations/ibr--locations.html.
(3) The ion-exchange resin identified in paragraph (a)(17) of this
section is used only for industrial application to treat bulk quantities
of aqueous food, including potable water, or for treatment of municipal
water supplies, subject to the condition that the temperature of the
food or water passing through the resin bed is maintained at 25 [deg]C
or less and the flow rate of the food or water passing through the bed
is not less than 2 gallons per cubic foot per minute.
(4) The ion-exchange resin identified in paragraph (a)(18) of this
section is used to treat aqueous sugar solutions subject to the
condition that the temperature of the sugar solution passing through the
resin bed is maintained at 82 [deg]C (179.6 [deg]F) or less and the flow
rate of the sugar solution passing through the bed is not less than 46.8
liters per cubic meter (0.35 gallon per cubic foot) of resin bed volume
per minute.
(5) The ion-exchange resin identified in paragraph (a)(20) of this
section is limited to use in aqueous process streams for the isolation
and purification of protein concentrates and isolates under the
following conditions:
(i) For resins that comply with the requirements in paragraph
(d)(2)(i) of this section, the pH range for the resin shall be no less
than 3.5 and no more than 9, and the temperatures of water and food
passing through the resin bed shall not exceed 25 [deg]C.
(ii) For resins that comply with the requirements in paragraph
(d)(2)(ii) of this section, the pH range for the resin shall be no less
than 2 and no more than 10, and the temperatures of water and food
passing through the resin shall not exceed 50 [deg]C.
(c) To insure safe use of ion-exchange resins, each ion-exchange
resin will be:
(1) Subjected to pre-use treatment by the manufacturer and/or the
user in accordance with the manufacturer's directions prescribed on the
label or labeling accompanying the resins, to guarantee a food-grade
purity of ion-exchange resins, in accordance with good manufacturing
practice.
(2) Accompanied by label or labeling to include directions for use
consistent with the intended functional purpose of the resin.
(3) Used in compliance with the label or labeling required by
paragraph (c)(2) of this section.
(4) Found to result in no more than 1 part per million of organic
extractives obtained with each of the named solvents, distilled water,
15 percent alcohol, and 5 percent acetic acid when, having been washed
and otherwise treated in accordance with the manufacturer's directions
for preparing them for use with food, the ion-exchange resin is
subjected to the following test: Using a separate ion-exchange column
for each solvent, prepare columns using 50 milliliters of the ready to
use ion-exchange resin that is to be tested. While maintaining the
highest temperature that will be encountered in use pass through these
beds at the rate of 350-450 milliliters per hour the three test solvents
distilled water, 15 percent (by volume) ethyl alcohol, and 5 percent (by
weight) acetic acid. The first liter of effluent from each solvent is
discarded, then the next 2 liters are used to determine organic
extractives. The 2-liter sample is carefully evaporated to constant
weight at 105 [deg]C; this is total extractives. This residue is fired
in a muffle furnace at 850 [deg]C to constant weight; this is ash. Total
extractives, minus ash equals the organic extractives. If the organic
extractives are greater than 1 part per million of the solvent used, a
blank should be run on the solvent and a correction should be made by
subtracting the total extractives obtained with the blank from the total
extractives obtained in the resin test.
[[Page 126]]
The solvents used are to be made as follows:
Distilled water (de-ionized water is distilled).
15 percent ethyl alcohol made by mixing 15 volumes of absolute ethyl
alcohol A.C.S. reagent grade, with 85 volumes of distilled de-ionized
water.
5 percent acetic acid made by mixing 5 parts by weight of A.C.S. reagent
grade glacial acetic acid with 95 parts by weight of distilled de-
ionized water.
In addition to the organic extractives limitation prescribed in this
paragraph, the ion-exchange resin identified in paragraph (a)(17) of
this section, when extracted with each of the named solvents, distilled
water, 50 percent alcohol, and 5 percent acetic acid, will be found to
result in not more than 7 parts per million of nitrogen extractives
(calculated as nitrogen) when the resin in the free-base form is
subjected to the following test immediately before each use: Using a
separate 1-inch diameter glass ion-exchange column for each solvent,
prepare each column using 100 milliliters of ready to use ion-exchange
resin that is to be tested. With the bottom outlet closed, fill each
ion-exchange column with one of the three solvents at a temperature of
25 [deg]C until the solvent level is even with the top of the resin bed.
Seal each column at the top and bottom and store in a vertical position
at a temperature of 25 [deg]C. After 96 hours, open the top of each
column, drain the solvent into a collection vessel, and analyze each
drained solvent and a solvent blank for nitrogen by a standard micro-
Kjeldahl method.
(d)(1) The ion-exchange resins identified in paragraphs (a)(1),
(a)(2), (a)(11), and (a)(15) of this section are exempted from the
acetic acid extraction requirement of paragraph (c)(4) of this section.
(2) The ion-exchange resin identified in paragraph (a)(20) of this
section shall comply either with:
(i) The extraction requirement in paragraph (c)(4) of this section
by using dilute sulfuric acid, pH 3.5 as a substitute for acetic acid;
or
(ii) The extraction requirement in paragraph (c)(4) of this section
by using reagent grade hydrochloric acid, diluted to pH 2, as a
substitute for acetic acid. The resin shall be found to result in no
more than 25 parts per million of organic extractives obtained with each
of the following solvents: Distilled water; 15 percent alcohol; and
hydrochloric acid, pH 2. Blanks should be run for each of the solvents,
and corrections should be made by subtracting the total extractives
obtained with the blank from the total extractives obtained in the resin
test.
(e) Acrylonitrile copolymers identified in this section shall comply
with the provisions of Sec. 180.22 of this chapter.
[42 FR 14526, Mar. 15, 1977, as amended at 46 FR 40181, Aug. 7, 1981; 46
FR 57033, Nov. 20, 1981; 49 FR 28830, July 17, 1984; 56 FR 16268, Apr.
22, 1991; 62 FR 7679, Feb. 20, 1997; 64 FR 14609, Mar. 26, 1999; 64 FR
56173, Oct. 18, 1999]
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