ISI 11-1e Determination of pH and Acid Factor of Starch

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1. Scope	The method is applicable to commercial native starch	LT 02. Dec. 1964 Rev. LT 16. Dec. 1997
2. Principle	Titration of 40 g starch in slurry with acid to pH 3.0.
3. Apparatus	3.1 Analytical balance weighing to the nearest 0.1 mg.
	3.2 pH meter
4. Reagents	4.1 Hydrochloric acid 0.1 N
5. Procedure	Weigh 40.0 g sample to the nearest 100 mg in a 250 ml beaker
	Add 100 ml distilled water and stir.
pH	Note pH of slurry
Titration	Titrate with burette and (4.1) to pH = 3.0 V = ml (4.2). N = normality of (4.2)
6. Calculation	Calculate acid factor of sample by averaging results of two samples with one decimal. Acid factor = 10 N V Report pH of starch slurry as pH of starch with one decimal.
	Eventually correct to value on sample dry matter.