Food and Drug Administration, HHS § 173.25 under the following prescribed condi- adjuvant substances required in the tions: production of such basic polymer. (a) The ion-exchange membrane is These optional adjuvant substances prepared by subjecting a polyethylene may include substances used in accord- base conforming to § 177.1520 of this ance with § 174.5 of this chapter. chapter to polymerization with styrene (c) Conditions of use. (1) until the polystyrene phase of the base Perfluorinated ion exchange mem- is not less than 16 percent nor more branes described in paragraph (a) of than 30 percent by weight. The base is this section may be used in contact then modified by reaction with with all types of liquid foods at tem- chloromethyl methyl ether, and by peratures not exceeding 70° (158 °F). subsequent amination with trimethyl- (2) Maximum thickness of the copoly- amine, dimethylamine, diethylene- mer membrane is 0.007 inch (0.017 centi- triamine, or dimethylethanolamine. meter). (b) The ion-exchange membrane is (3) Perfluorinated ion exchange mem- manufactured so as to comply with the branes shall be maintained in a sani- following extraction limitations when tary manner in accordance with cur- subjected to the described procedure: rent good manufacturing practice so as Separate square-foot samples of mem- to prevent microbial adulteration of brane weighing approximately 14 grams food. each are cut into small pieces and (4) To assure their safe use, refluxed for 4 hours in 150 cubic centi- perfluorinated ionomer membranes meters of the following solvents: Dis- shall be thoroughly cleaned prior to tilled water, 5 percent acetic acid, and their first use in accordance with cur- 50 percent alcohol. Extraction from rent good manufacturing practice. each sample will not exceed 0.4 percent by weight of sample. [59 FR 15623, Apr. 4, 1994] (c) The ion-exchange membrane will § 173.25 Ion-exchange resins. be used in the production of grapefruit juice to adjust the ratio of citric acid Ion-exchange resins may be safely to total solids of the grapefruit juice used in the treatment of food under the produced. following prescribed conditions: (a) The ion-exchange resins are pre- § 173.21 Perfluorinated ion exchange pared in appropriate physical form, and membranes. consist of one or more of the following: Substances identified in paragraph (1) Sulfonated copolymer of styrene (a) of this section may be safely used as and divinylbenzene. ion exchange membranes intended for (2) Sulfonated anthracite coal meet- use in the treatment of bulk quantities ing the requirements of ASTM method of liquid food under the following pre- D388–38, Class I, Group 2, ‘‘Standard scribed conditions: Specifications for Classification of Coal (a) Identity. The membrane is a co- by Rank,’’ which is incorporated by polymer of ethanesulfonyl fluoride, 2- reference. Copies are available from [1-[difluoro-[(trifluoro- University Microfilms International, ethenyl)oxy]methyl]-1,2,2,2-tetrafluoro- 300 N. Zeeb Rd., Ann Arbor, MI 48106, or ethoxy]-1,1,2,2,-tetrafluoro-, with tetra- available for inspection at the National fluoroethylene that has been subse- Archives and Records Administration quently treated to hydrolyze the (NARA). For information on the avail- sulfonyl fluoride group to the sulfonic ability of this material at NARA, call acid. The Chemical Abstracts Service 202–741–6030, or go to: http:// name of this polymer is ethanesulfonic www.archives.gov/federallregister/ acid, 2-[1-[difluoro-[(trifluoro- codeloflfederallregulations/ ethenyl)oxy]methyl]-1,2,2,2-tetrafluoro- ibrllocations.html. ethoxy]-1,1,2,2,-tetrafluoro-, polymer (3) Sulfite-modified cross-linked phe- with tetrafluoroethane (CAS Reg. No. nol-formaldehyde, with modification 31175–20–9). resulting in sulfonic acid groups on (b) Optional adjuvant substances. The side chains. basic polymer identified in paragraph (4) Methacrylic acid-divinylbenzene (a) of this section may contain optional copolymer. 125 VerDate Mar<15>2010 13:59 Jul 24, 2014 Jkt 232072 PO 00000 Frm 00135 Fmt 8010 Sfmt 8010 Y:\SGML\232072.XXX 232072 pmangrum on DSK3VPTVN1PROD with CFR § 173.25 21 CFR Ch. I (4–1–14 Edition) (5) Cross-linked polystyrene, first (18) Methyl acrylate-divinylbenzene- chloromethylated then aminated with diethylene glycol divinyl ether trimethylamine, dimethylamine, di- terpolymer containing not less than 7 ethylenetriamine, or dimethylethanol- percent by weight of divinylbenzene amine. and not more than 2.3 percent by (6) Diethylenetriamine, triethylene- weight of diethylene glycol divinyl tetramine, or tetraethylenepentamine ether, aminolyzed with dimethyl- cross-linked with epichlorohydrin. aminopropylamine and quaternized (7) Cross-linked phenol-formaldehyde with methyl chloride. activated with one or both of the fol- (19) Epichlorohydrin cross-linked lowing: Triethylene tetramine and with ammonia and then quaternized tetraethylenepentamine. with methyl chloride to contain not (8) Reaction resin of formaldehyde, more than 18 percent strong base ca- acetone, and tetraethylenepentamine. pacity by weight of total exchange ca- (9) Completely hydrolyzed copoly- pacity [Chemical Abstracts Service mers of methyl acrylate and name: Oxirane (chloromethyl)-, poly- divinylbenzene. mer with ammonia, reaction product with chloromethane; CAS Reg. No. (10) Completely hydrolyzed 68036–99–7]. terpolymers of methyl acrylate, (20) Regenerated cellulose, cross- divinylbenzene, and acrylonitrile. linked and alkylated with epichloro- (11) Sulfonated terpolymers of sty- hydrin and propylene oxide, then sulfo- rene, divinylbenzene, and acrylonitrile nated whereby the amount of epi- or methyl acrylate. chlorohydrin plus propylene oxide em- (12) Methyl acrylate-divinylbenzene ployed does not exceed 250 percent by copolymer containing not less than 2 weight of the starting quantity of cel- percent by weight of divinylbenzene, lulose. aminolyzed with dimethylaminopro- (b) Ion-exchange resins are used in pylamine. the purification of foods, including po- (13) Methyl acrylate-divinylbenzene table water, to remove undesirable ions copolymer containing not less than 3.5 or to replace less desirable ions with percent by weight of divinylbenzene, one or more of the following: bicarbon- aminolyzed with dimethylaminopro- ate, calcium, carbonate, chloride, hy- pylamine. drogen, hydroxyl, magnesium, potas- (14) Epichlorohydrin cross-linked sium, sodium, and sulfate except that: with ammonia. The ion-exchange resin identified in (15) Sulfonated tetrapolymer of sty- paragraph (a)(12) of this section is used rene, divinylbenzene, acrylonitrile, and only in accordance with paragraph methyl acrylate derived from a mix- (b)(1) of this section, the ion-exchange ture of monomers containing not more resin identified in paragraph (a)(13) of than a total of 2 percent by weight of this section is used only in accordance acrylonitrile and methyl acrylate. with paragraph (b)(2) of this section, (16) Methyl acrylate-divinylbenzene- the resin identified in paragraph (a)(16) diethylene glycol divinyl ether of this section is used only in accord- terpolymer containing not less than 3.5 ance with paragraph (b)(1) or (b)(2) of percent by weight of divinylbenzene this section, the ion-exchange resin and not more than 0.6 percent by identified in paragraph (a)(17) of this weight of diethylene glycol divinyl section is used only in accordance with ether, aminolyzed with dimethyl- paragraph (b)(3) of this section, the aminopropylamine. ion-exchange resin identified in para- (17) Styrene-divinylbenzene cross- graph (a)(18) of this section is used only linked copolymer, first in accordance with paragraph (b)(4) of chloromethylated then aminated with this section, and the ion-exchange dimethylamine and oxidized with hy- resin identified in paragraph (a)(20) of drogen peroxide whereby the resin con- this section is used only in accordance tains not more than 15 percent by with paragraphs (b)(5) and (d) of this weight of vinyl N,N-dimethylbenzyl- section. amine-N-oxide and not more than 6.5 (1) The ion-exchange resins identified percent by weight of nitrogen. in paragraphs (a) (12) and (16) of this 126 VerDate Mar<15>2010 13:59 Jul 24, 2014 Jkt 232072 PO 00000 Frm 00136 Fmt 8010 Sfmt 8010 Y:\SGML\232072.XXX 232072 pmangrum on DSK3VPTVN1PROD with CFR Food and Drug Administration, HHS § 173.25 section are used to treat water for use food passing through the resin bed is in the manufacture of distilled alco- maintained at 50 °C or less and the flow holic beverages, subject to the fol- rate of the water or food passing lowing conditions: through the bed is not less than 0.5 gal- (i) The water is subjected to treat- lon per cubic foot per minute. ment through a mixed bed consisting of (ii) The ion-exchange resin identified one of the resins identified in para- in paragraph (a)(16) of this section is graph (a) (12) or (16) of this section and used to treat water and aqueous food one of the strongly acidic cation-ex- only of the types identified under cat- change resins in the hydrogen form egories I, II, and VI-B in Table 1 of identified in paragraphs (a) (1), (2), and § 176.170(c) of this chapter, Provided, (11) of this section; or that either: (ii) The water is first subjected to (A) The temperature of the water or one of the resins identified in para- food passing through the resin bed is graph (a) (12) or (16) of this section and maintained at 50 °C or less and the flow is subsequently subjected to treatment rate of the water or food passing through a bed of activated