Add 2.0ml of DNS reagent to the above test tubes, heat in a boiling water bath for 2 minutes for color development, remove and rapidly cool with running water. Add 9.0ml of distilled water to each tube, shake the hook, and measure the light absorption value at a wavelength of 540mm. Replace the glucose standard solution with 1.0ml of distilled water and adjust the blank to zero using the same color development procedure. Draw a standard curve with glucose content (mg) as the horizontal axis and light absorption value as the vertical axis.

Extraction of reducing sugars from samples

Accurately weigh 0.5g of Qifen and place it in a 100ml beaker. First, mix it into a paste with a small amount of distilled water (about 2m), then add 40ml of distilled water, mix well, and keep it in a 50C constant temperature water bath for 20 minutes. Stir occasionally to allow the reducing sugar to leach out and mix. Filter and collect all the filtrate in a 50ml volumetric flask, then dilute to full volume with distilled water to obtain the reducing sugar extract.

1. Hydrolysis and extraction of total sugar in the sample

Accurately weigh 0.5g of corn starch and place it in a conical flask. Add 10ml of 6mol/L HCl and 15ml of distilled water, and heat it in boiling water for 0.5h. Take out 1-2 drops and place them on a white porcelain plate. Add 1 drop of 1-KI solution to check if the hydrolysis is sufficient. If ❽ has already been hydrolyzed, blue will not appear earlier. After hydrolysis is complete, cool to room temperature and add 1 drop of phthalein indicator. Neutralize the bath with 6N NaOH solution to a slight red color and dilute to 100ml. Filter 10ml of the filtrate and transfer to a 100ml volumetric flask. Fill the flask to the full mark and mix to obtain a total sugar hydrolysate diluted 1000 times for total sugar determination.

4、 Determination of Analysis Content in Samples

Take 7 15mm x 180mm test tubes and add reagents according to the length: