Dextrin is starch, or partially hydrolyzed starch, modified by heating in a dry state, with or without acids, alkalies, or pH control agents. During heating, moisture may be added.
Sample: 1 g
Analysis:Suspend the Sample in 20 mL of water, and add a few drops of iodine TS.
Acceptance criteria: A blue to reddish-brown color results.
• B. Dextrin is very soluble in boiling water, forming a mucilaginous solution (difference from starch).
• Reducing Sugars (Dextrose Equivalent)
Sample: A quantity of Dextrin equivalent to 2.0 g on the dried basis
Analysis: To the Sample add 100 mL of water, shake for 30 min, dilute with water to 200 mL, accurately measured, and filter. To 10.0 mL of alkaline cupric tartrate TS add 20.0 mL of the filtrate, mix, and heat on a hot plate adjusted to bring the solution to a boil in 3 min. Boil for 2 min, and cool quickly. Add 5 mL of potassium iodide solution (3 in 10) and 10 mL of 2 N sulfuric acid, mix, and titrate immediately with 0.1 N sodium thiosulfate VS, using starch TS, added toward the end of the titration, as an indicator.
Repeat the procedure beginning with To 10.0 mL of alkaline cupric tartrate TS using, in place of the filtrate, 20.0 mL of a solution (1 in 1000) of anhydrous dextrose, accurately prepared. Perform a blank titration.
Compare (VB VU) and (VB VS).
Result 1 = (VB VU)
Result 2 = (VB VS)
Acceptance criteria: (VB VU) is NMT (VB VS), corresponding to NMT 10%, calculated as dextrose (C6H12O6).
• Residue on Ignition 281: NMT 0.5%
• Chloride and Sulfate, Chloride 221
Sample: 3.0 g
Control: 2.8 mL of 0.020 N hydrochloric acid in 75 mL of water
Analysis: Dissolve the Sample in 75 mL of boiling water. Cool, dilute with water to 75 mL, and filter if necessary. To 25 mL of this solution and the Control, add 2 mL of nitric acid and 1 mL of silver nitrate TS.
Acceptance criteria: Any turbidity produced is NMT that of the Control, corresponding to NMT 0.2% of chloride.
• Heavy Metals, Method II 231: NMT 20 ppm
• Limit of Protein
Sample: 10 g
Analysis: Proceed as directed in Nitrogen Determination 461, using the Sample instead of 1 g, 60 mL of sulfuric acid instead of 20 mL, and multiplying the percentage of nitrogen found by 6.25.
Acceptance criteria: NMT 1.0%
Sample: 10.0 g
Analysis: Add the Sample to 100 mL of 70% alcohol, previously neutralized to phenolphthalein. Shake for 1 h, filter, and titrate 50 mL of the filtrate with 0.10 N sodium hydroxide.
Acceptance criteria: NMT 3.0 mL
• Botanic Characteristics
Microscopic: Granules are similar in appearance to the starch from which the Dextrin has been prepared, except that when prepared from corn starch, many of the granules show concentric striations, and when prepared from potato starch, concentric striations are not clearly visible; the hilum is frequently bicleft; and a small proportion of the granules are distorted.
• Loss on Drying 731: Dry a sample at a pressure not exceeding 100 mm of mercury at 120 for 4 h: it loses NMT 13.0% of its weight.
• Packaging and Storage: Preserve in well-closed containers.