---
kind: "section"
citation: "21 C.F.R. § 173.357"
title: "21"
number: "173.357"
heading: "Materials used as fixing agents in the immobilization of enzyme preparations."
url: "https://uscodex.org/cfr/21/173.357"
---

# §173.357. Materials used as fixing agents in the immobilization of enzyme preparations.


Fixing agents may be safely used in the immobilization of enzyme preparations in accordance with the following conditions:

- (a) **The materials consist of one or more of the following—**
  - (1) **Substances generally recognized as safe in food.**
  - (2) **Substances identified in this subparagraph and subject to such limitations as are provided—**
- (b) **The fixed enzyme preparation is washed to remove residues of the fixing materials.**

## Notes

### Amendments

[48 FR 5716, Feb. 8, 1983, as amended at 52 FR 39512, Oct. 22, 1987; 55 FR 12172, Apr. 2, 1990; 59 FR 36937, July 20, 1994; 61 FR 4873, Feb. 9, 1996; 61 FR 14245, Apr. 1, 1996; 67 FR 42716, June 25, 2002; 81 FR 5592, Feb. 3, 2016; 88 FR 17723, Mar. 24, 2023]

### Authority

Authority: 21 U.S.C. 321, 342, 348.

### Source

Source: 42 FR 14526, Mar. 15, 1977, unless otherwise noted.

### Amendments

[48 FR 5716, Feb. 8, 1983, as amended at 52 FR 39512, Oct. 22, 1987; 55 FR 12172, Apr. 2, 1990; 59 FR 36937, July 20, 1994; 61 FR 4873, Feb. 9, 1996; 61 FR 14245, Apr. 1, 1996; 67 FR 42716, June 25, 2002; 81 FR 5592, Feb. 3, 2016; 88 FR 17723, Mar. 24, 2023]