Starch content detection

There are many methods for detecting starch content. Here are some common methods:

1. Chemical method
Sulfuric acid heating method
Principle: Mix the sample with dilute sulfuric acid. Under heating conditions, the starch will be hydrolyzed into sugar by acid. The sugar content in the sample is determined by subsequent titration or reaction, and then the starch content is calculated.
Scope of application: Applicable to all kinds of starch-containing samples.
Hydrolytic enzyme method
Principle: After removing fat and soluble sugars from the sample, the starch is hydrolyzed into disaccharides by amylase, and then the disaccharides are hydrolyzed into monosaccharides by hydrochloric acid and then converted into starch according to the reducing sugar determination.
Scope of application: Applicable to all foods containing starch.
Required instruments: reflux condenser, water bath, etc.
Required reagents: ether, 0.5% amylase solution, iodine solution, 85% ethanol, etc.
Operation steps: including sample treatment, amylase hydrolysis, acid hydrolysis, reducing sugar determination, etc.
2. Physical method
Agarose infiltration method
Principle: Mix the sample to be tested with agarose solution, form a gel after heating and cooling, and judge the amount of starch in the sample by observing the transparency of the gel.
Scope of application: Applicable to occasions where the starch content needs to be judged intuitively.
Weight determination method
Principle: After the sample is dried under certain conditions, the dry weight of the sample is measured, and then the starch content in the sample is calculated through a series of calculations.
Scope of application: Applicable to occasions where the starch content needs to be accurately determined.
3. Rapid detection method
Iodine solution detection method
Principle: Iodine reacts with starch to form a blue complex. The presence and content of starch can be determined by observing the color change.
Operation steps: Add iodine solution to a small amount of the test solution. If it is lavender or blue, it means that starch is present.
Note: The iodine solution detection method is suitable for quickly and easily detecting the presence of starch, but it cannot accurately determine the starch content.
Tyndall phenomenon method
Principle: Starch dissolved in water will form a colloid. When light passes through the colloid, the Tyndall phenomenon will occur (that is, light is scattered in the colloid).
Operation steps: Put the liquid to be tested into a transparent glass cup, place it in a darker place, and use a flashlight to illuminate the liquid in the cup from the side. If you see small particles in the light column, it means that starch exists.
Scope of application: This method is suitable for occasions where it is necessary to quickly detect whether starch exists.
4. Other methods
Monosaccharide, disaccharide, starch system determination method
Principle: Simultaneously determine the content of monosaccharides, disaccharides, and starch in the sample, and the starch content can be obtained by calculation.
Scope of application: Applicable to occasions where the content of multiple carbohydrates needs to be determined simultaneously.
Enzyme-direct method
Principle: Use specific enzymes to directly hydrolyze starch and determine the hydrolysis product to infer the starch content.
Scope of application: Applicable to occasions where the starch content needs to be determined quickly and accurately.
In summary, there are many methods for detecting starch content, and the choice of which method depends on factors such as the specific application scenario, sample type, and required accuracy. In actual operation, it is necessary to select a suitable method according to the experimental conditions and requirements, and strictly follow the operating procedures to ensure the accuracy of the measurement results.