To understand the principles and methods of determining sucrose content in plant tissues.

Operation method

Experiments for the determination of sucrose content in plants

Principle

Soluble sugars in plants include reducing sugars and non-reducing sugars (mainly sucrose). Therefore, when determining sucrose, hydrochloric acid must first be used to hydrolyze it to reducing sugar, and then determine the total reducing sugar content after hydrolysis, and then subtract the reducing sugar content before hydrolysis from the total reducing sugar content, that is, the sucrose content.

Materials and Instruments

Potato Fruit
Hydrochloric acid solution Sodium hydroxide solution Phenolphthalein indicator
Spectrophotometer Electronic analytical balance Constant temperature water bath 25 ml graduated test tubes 50 ml volumetric flasks 100 ml triangular flasks Test tube racks Pipettes Pipette racks Earwash balls Glass rods

Move

1. The standard curve of glucose is the same as the above determination of reducing sugar content.

2. Hydrolysis of sucrose in the sample

Accurately absorb 10 ml of sugar extract for the above determination of reducing sugar content in a 100 ml triangular flask, add 6 mol-L-1 hydrochloric acid 10 ml, shake well, heating in a boiling water bath for 10min, after cooling, add phenolphthalein indicator a drop, neutralize with 10% sodium hydroxide until the solution is slightly red, then transfer the extract into a 50 ml volumetric flask with distilled water and dilute to the scale. Then the extract was transferred into a 50 ml volumetric flask with distilled water and diluted to scale, to be measured.

3. Determination of total reducing sugars in the sample

Take four 25 ml graduated test tubes, numbered, three of them (three replicates) were added with 2 ml of the solution to be measured, one blank tube was added with 2 ml of the solution to be measured, one blank tube was added with 2 ml of the solution to be measured.

2 ml of distilled water, and then each tube and then add DNS reagent 1.5 ml, shake well, the mixture was heated in a boiling water bath for 5 min, and then cooled with tap water, each add 21.5 ml of distilled water so that the total volume of 25 ml, shake well, and determine the absorbance (A) value at 520 nm.

Common Problems

According to the absorbance value of the liquid to be measured, the corresponding reducing sugar content was found from the above standard curve, and then the percentage of total soluble sugar and total sucrose in the sample was calculated according to the following formula.

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