Soluble sugar content determination in plant tissue (phenol method)

The carbon nutrient status of plants and the quality characteristics of agricultural products are often taken as important indicators, and plants in order to adapt to adversity conditions, such as drought, low temperature, will also actively accumulate some soluble sugars, reduce penetration and freezing point, in order to adapt to changes in external environmental conditions.
, principle
phenol method to determine the principle of soluble sugar:
plant soluble sugar mainly refers to the soluble sugar and oligosaccharides soluble in water and ethanol. The principle of phenol method to determine soluble sugar is: sugar under the action of strong sulfuric acid, dehydrated acetaldehyde or hydroxymethyl acetaldehyde (molecularly available ketone method) can be synthesized with phenol to synthesize an orange-red
compound
, in the range of 10 to 100 mg its color depth is positively compared with the content of sugar, and at 485nm wavelength there is the maximum absorption peak, so the available color is measured at this long wave. Phenol method can be used for methylated sugar, sugar and polysaccharide determination, the method is simple,
reagents
cheap, high sensitivity, the experiment is basically not affected by the presence of
protein
, and the resulting color can be stable more than 160min.
, materials,
equipment
and reagents(i) materials: fresh plant leaves.
(ii) Instruments and equipment: 1. Hydrometer; 2. Water bath pot; 3. Scale
tubub tube
; 4. scale
straw
.
(iii) reagents: 1. 90% phenol solution called 90 g phenol (AR), 10 ml dissolved with distilled water, can be stored at room temperature for several months; 9% phenol solution take 3 ml 90% phenol solution, add distilled water to 30 ml, is now desirable; 3. strong sulfuric acid (specific gravity 1.84); 4. 1% sucrose standard solution will analyze the pure sucrose baked at 80 degrees C to constant weight, accurately weighing 1.000 grams. Dissolve with a small amount of water, transfer to 100 ml
capacity bottle
, add 0.5 ml of thick sulphuric acid, with distilled water to the scale;
, the experimental steps1. Standard curve system: to the test tube to add 1 ml of 9% phenol solution, shake well, and then from the front of the tube to 5 to 20S to add 5 ml of thick sulfuric acid, shake well. The total volume of color fluid is 8 ml, at room temperature to place 30min, color. Then, with blankness as the reference, the color is compared at 485nm wavelength, the sugar content is the horizontal coordinates, the absorbance is the ordinate, the standard curve is drawn, and the standard linear equation is found.
2. Extraction of soluble sugars: take fresh plant leaves, wipe the surface dirt, cut and mix well, weigh 0.10 to 0.30g, a total of 3 servings (or dry material), respectively, into 3 scale test tubes, Add 5 to 10 ml distilled water, plastic film seal, extract 30min (extract 2 times) in boiling water, extract
filtration
into a 25 ml capacity bottle, repeatedly rinse test tubes and residues, fixed to scale.
3. Measure the absorption of 0.5 ml of sample fluid in the test tube (repeat 2 times), add 1.5 ml of distilled water, with the steps of making a standard curve, in order to add phenol, thick sulfuric acid solution, color and determine absorbance. The amount of sugar is found by the standard curve.
, the result calculationThe sugar content of the test sample is calculated by pressing:
soluble sugar content (%) - the amount of sugar found from the standard curve (g) × extracts the liquid product (ml) × dilution multiplied × (ml) × sample weight (g) ×106) ×100