• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

CFR - Code of Federal Regulations Title 21

  • Print
  • Share
  • E-mail
-

The information on this page is current as of April 1 2019.

For the most up-to-date version of CFR Title 21, go to the Electronic Code of Federal Regulations (eCFR).

New Search
Help | More About 21CFR
[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2019]
[CITE: 21CFR173.21]



TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION
DEPARTMENT OF HEALTH AND HUMAN SERVICES
SUBCHAPTER B--FOOD FOR HUMAN CONSUMPTION (CONTINUED)

PART 173 -- SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION

Subpart A--Polymer Substances and Polymer Adjuvants for Food Treatment

Sec. 173.21 Perfluorinated ion exchange membranes.

Substances identified in paragraph (a) of this section may be safely used as ion exchange membranes intended for use in the treatment of bulk quantities of liquid food under the following prescribed conditions:

(a) Identity. The membrane is a copolymer of ethanesulfonyl fluoride, 2-[1-[difluoro-[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2,-tetrafluoro-, with tetrafluoroethylene that has been subsequently treated to hydrolyze the sulfonyl fluoride group to the sulfonic acid. The Chemical Abstracts Service name of this polymer is ethanesulfonic acid, 2-[1-[difluoro-[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2,-tetrafluoro-, polymer with tetrafluoroethane (CAS Reg. No. 31175-20-9).

(b) Optional adjuvant substances. The basic polymer identified in paragraph (a) of this section may contain optional adjuvant substances required in the production of such basic polymer. These optional adjuvant substances may include substances used in accordance with 174.5 of this chapter.

(c) Conditions of use. (1) Perfluorinated ion exchange membranes described in paragraph (a) of this section may be used in contact with all types of liquid foods at temperatures not exceeding 70deg. (158 deg. F).

(2) Maximum thickness of the copolymer membrane is 0.007 inch (0.017 centimeter).

(3) Perfluorinated ion exchange membranes shall be maintained in a sanitary manner in accordance with current good manufacturing practice so as to prevent microbial adulteration of food.

(4) To assure their safe use, perfluorinated ionomer membranes shall be thoroughly cleaned prior to their first use in accordance with current good manufacturing practice.

[59 FR 15623, Apr. 4, 1994]

-
-