Application case of DSC in starch gelatinization

　　Differential scanning calorimeterWidely used in the study of food properties, by measuring parameters such as peak position, peak value, peak area, etc., the phase transition temperature, enthalpy, crystallization temperature, melting point, etc. of food components can be analyzed. The test case shared this time is to use a differential scanning calorimeter to test starch. The temperature and amount of heat absorbed by starch during gelatinization can be studied using a DSC differential scanning calorimeter to observe this endothermic phenomenon and understand the impact of gelatinization temperature on food quality and processing characteristics.

　　1. The meaning of starch gelatinization

The gelatinization of starch refers to the process where granular starch is added to a certain proportion of water and heated, causing the starch particles to absorb water and expand. Starch molecules begin to vibrate violently, breaking the hydrogen bonds between crystalline and amorphous starch molecules. At this point, a large amount of water is sucked into the original hydrogen bond positions, causing the crystalline region of starch to gradually disappear. When the crystalline region completely disappears, it is called gelatinization, and the temperature at this point is called the gelatinization temperature.

　　2. Application principle of DSC in starch gelatinization

DSC is used to detect the endothermic or exothermic reactions of the sample being tested as the temperature increases, and to collect real-time data when the sample is heated; When starch is mixed with water, the water will form a chain water crystal structure with the starch molecular chains. As the temperature increases, this structure will show a clear endothermic melting peak, and the melting temperature and heat absorption of different concentrations will vary. DSC can calculate the area of the formed peak to determine the heat absorption and thus understand the degree of gelatinization.

　　3. Operation method for measuring starch gelatinization by DSC

(1) Experimental equipment: DZ-DSC300 differential scanning calorimeter

(2) Sample preparation: Take 3mg of wheat starch and place it in an aluminum crucible, then drip 5ul of water and mix it, and seal it with a tablet press.

(3) Instrument usage: Use standard indium metal to calibrate the melting point and enthalpy value for testing. Place the crucible with the sample on the right side of the tray and a blank control aluminum crucible with a lid on the left side; Set the temperature to 200 ℃, with a heating rate of 10 ℃/min, and introduce 50ml/min of nitrogen gas for the experiment.

(4) Experimental diagram:

(5) Result analysis: When starch and water are just mixed, there is no exothermic reaction between them. When the temperature reaches 88.0 ℃, the reaction begins and there is an endothermic phenomenon. The peak temperature is 103.0 ℃, and the endothermic effect of the sample ends at 107.1 ℃. The area of the entire endothermic peak is the energy absorbed by starch gelatinization.

　　4. Experimental conclusion

DSC determines the starch gelatinization temperature through sample and left blank control experiments, and its peak area is the degree of starch gelatinization. After gelatinization tests on wheat starch, corn starch, and potato starch, it was found that corn starch has the highest gelatinization temperature and requires the most energy.

In addition to its application in the food industry, differential scanning calorimetry is also used in industries such as plastics, rubber, coatings, pharmaceuticals, metal materials, and composite materials. For different materials and testing needs, Nanjing Dazhan Instrument can match corresponding instruments to provide customers with suitable products and professional after-sales service.