Modified Starch
DEFINITION
Modified Starch is Starch modified by chemical means. Food Starch may be acid-modified, bleached, oxidized, esterified, etherified, or treated enzymatically to change its functional properties (21 CFR 172.892).
IDENTIFICATION
• A.
Corn starch:
Polygonal, rounded, or spheroidal granules up to 35 µm in diameter and usually having a circular or several-rayed central cleft
Tapioca starch:
Spherical granules with one truncated side, typically 5–35 µm in diameter and usually having a circular or several-rayed central cleft
Potato starch:
Irregularly shaped, ovoid, or pear-shaped granules, usually 30–100 µm in size but occasionally exceeding 100 µm; or rounded, 10–35 µm in size. There are occasional compound granules having two to four components. The ovoid and pear-shaped granules have an eccentric hilum, and the rounded granules have an accentric or slightly eccentric hilum. All granules show clearly visible concentric striations.
Wheat starch:
Large and small granules, usually 10–60 µm in diameter. The central hilum and striations are visible or barely visible.
• B.
Sodium hydroxide solution:
2% (w/w)
Sample:
0.6 g
Analysis:
Transfer the Sample to a 25-mL glass vial with a plastic cap. Add 9.4 g of water, cap, and shake vigorously to evenly disperse the starch. Add 10 g of the Sodium hydroxide solution, cap, and shake vigorously for 1 min to create a smooth mixture. Evaluate within 1 min.
Acceptance criteria:
The final solution is translucent to opaque with a fluid consistency. A yellow tint of the final solution is acceptable.
• C.
A water slurry of the Modified Starch is colored orange-red to deep blue by iodine TS.
IMPURITIES
• Residue on Ignition 
281
281
Sample:
2.0 ± 0.1 g
Analysis:
Proceed as directed in the chapter.
Acceptance criteria:
NMT 1.5%
• Iron 241
241
Test preparation:
Dissolve the residue obtained in the test for Residue on Ignition in 8 mL of hydrochloric acid with the aid of gentle heating. Dilute with water to 100 mL in a volumetric flask, and mix. Dilute 25 mL of this solution with water to 47 ± 1 mL.
Analysis:
Proceed as directed in the chapter.
Acceptance criteria:
NMT 20 ppm
• Limit of Sulfur Dioxide
Sample:
20.0 ± 0.1 g
Analysis:
Mix the Sample with 200 mL of 5% alcohol until a smooth suspension is obtained, and vacuum-filter through paper (Whatman No.1 or equivalent). To 100 mL of the filtrate add 3 mL of starch TS, and titrate with 0.01 N iodine VS to the first permanent blue color.
Acceptance criteria:
NMT 1.7 mL of 0.01 N iodine VS is consumed, which corresponds to NMT 50 ppm of sulfur dioxide being found
• Oxidizing Substances
Sample:
4.0 g
Titrimetric system
Mode:
Direct titration
Titrant:
0.002 N sodium thiosulfate VS
Blank:
30.0 mL of water, accurately measured
Endpoint detection:
Visual
Analysis:
Transfer the Sample to a glass-stoppered, 125-mL conical flask, and add 50.0 mL of water. Insert the stopper, and swirl for 5 min. Transfer to a glass-stoppered, 50-mL centrifuge tube, and centrifuge to clarify. Transfer 30.0 mL of the clear supernatant to a glass-stoppered, 125-mL conical flask. Add 1 mL of glacial acetic acid and 0.5–1.0 g of potassium iodide. Insert the stopper, swirl, and allow to stand for 25–30 min in the dark. Add 1 mL of starch TS, and titrate with Titrant to the disappearance of the starch–iodine color. Perform a blank determination, and make any necessary correction. Each mL of 0.002 N sodium thiosulfate is equivalent to 34 µg of oxidant, calculated as hydrogen peroxide.
Acceptance criteria:
NMT 12.6 mL of 0.002 N sodium thiosulfate is required (180 ppm, calculated as H2O2), which corresponds to NMT 0.018% of oxidizing substances
SPECIFIC TESTS
• Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62:
The total aerobic microbial count does not exceed 103 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g. It meets the requirements of the tests for absence of Salmonella species and Escherichia coli.
61 and Tests for Specified Microorganisms 62:
The total aerobic microbial count does not exceed 103 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g. It meets the requirements of the tests for absence of Salmonella species and Escherichia coli.
• pH 791
791
Sample:
20.0 ± 0.1 g
Analysis:
Transfer the Sample to a suitable nonmetallic container, and add 100 mL of water to obtain a slurry. Stir using a magnetic stirrer at a moderate rate for 5 min, and determine the pH to the nearest 0.1 unit.
Acceptance criteria:
3.0–9.0
• Loss on Drying 731
731
Analysis:
Dry a sample at 120
for 4 h.
for 4 h.
Acceptance criteria
Corn starch and Wheat starch:
NMT 15.0%
Tapioca starch:
NMT 18.0%
Potato starch:
NMT 21.0%
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers. No storage requirements specified.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
| 61 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| 62 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
USP35–NF30 Page 1971
Pharmacopeial Forum: Volume No. 30(4) Page 1334