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173.20 Ion-exchange membranes.

Home > Regulations > Secondary direct food additives permitted in food for human consumption > 173.20 Ion-exchange membranes.



[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR173.20]

[Page 121]
 
                        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 
CONSUMPTION--Table of Contents
 
  Subpart A_Polymer Substances and Polymer Adjuvants for Food Treatment
 
Sec.  173.20  Ion-exchange membranes.

    Ion-exchange membranes may be safely used in the processing of food 
under the following prescribed conditions:
    (a) The ion-exchange membrane is prepared by subjecting a 
polyethylene base conforming to Sec.  177.1520 of this chapter to 
polymerization with styrene until the polystyrene phase of the base is 
not less than 16 percent nor more than 30 percent by weight. The base is 
then modified by reaction with chloromethyl methyl ether, and by 
subsequent amination with tri methyl amine, di methyl amine, di ethyl 
ene triamine, or di methyl ethanol amine.
    (b) The ion-exchange membrane is manufactured so as to comply with 
the following extraction limitations when subjected to the described 
procedure: Separate square-foot samples of membrane weighing 
approximately 14 grams each are cut into small pieces and refluxed for 4 
hours in 150 cubic centimeters of the following solvents: Distilled 
water, 5 percent acetic acid, and 50 percent alcohol. Extraction from 
each sample will not exceed 0.4 percent by weight of sample.
    (c) The ion-exchange membrane will be used in the production of 
grapefruit juice to adjust the ratio of citric acid to total solids of 
the grapefruit juice produced.





Additives that reference this regulation:


Source: U.S. Code of Federal Regulations - CFR Title 21, Part 173, Section 20


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