CN115015497A - Method for measuring glycemic index in vivo and its application in screening low-glycemic potato varieties - Google Patents

Abstract

The invention relates to the technical field of potato cultivation, in particular to a method for determining in-vivo glycemic index and application of screening low-glycemic potato varieties, wherein the method comprises the following steps: (1) making a blood glucose response curve according to food; (2) making a blood sugar reaction curve of the potato; (3) determination of the glycemic index of potatoes: the glycemic index of potatoes was calculated according to the following formula: GIt ═ At × 100/Aref where At is the area under the glycemic response curve of the test food; aref is the area under the glycemic response curve for the reference food; calculating the average value of each tested individual GIt, wherein the average value is represented as the standard deviation of the average value, namely the glycemic index GI; the method has the advantages of simple determination process, quick analysis process and high accuracy; the glycemic indexes of the potato varieties are analyzed by combining an in-vitro measuring mode, so that accurate glycemic index values of different varieties of potatoes are obtained, and low-glycemic type potato varieties are screened.

Description

Method for measuring glycemic index in vivo and its application in screening low-glycemic potato varieties

technical field

The invention relates to the technical field of potato cultivation, in particular to a method for measuring the glycemic index in vivo and the application of screening low-glycemic potato varieties.

Background technique

Potato (Solanum tuberosum L.) is the most important food and vegetable crops in the world, and its photosynthetic products are mainly stored in tubers. As the main edible part, tubers are rich in nutrients such as carbohydrates, proteins, vitamins and minerals. The composition and content of nutrients in tubers are affected by factors such as variety, cultivation and storage, while the bioavailability of nutrients is affected by the composition and content of nutrients, individual absorption capacity and processing methods. With the substantial increase in the output of major food crops including potatoes, the food consumption demand of Chinese residents has shifted from satiety to nutrition and health. The breeding goal of potato and other food crops should also be changed from yield-oriented to quality-oriented, to upgrade nutritional quality, and to alleviate "invisible hunger" and nutrition-related diseases from the source.

There are two ways to measure the glycemic index: in vivo and in vitro. The in vivo measurement results can more realistically reflect the glycemic index of potatoes, but the testing process is cumbersome, labor-intensive and material-intensive, and the measurement results are affected by the participants' own physique and testing procedures. The estimated value of the glycemic index of potato is obtained by setting a digestion procedure close to the in vivo measurement, which is not affected by the physical fitness of the participants, and can measure a large number of samples, which is less time-consuming. The measurement of glycemic index is currently commonly used in staple crops such as rice and wheat and their products. The measurement of the glycemic index of potato tubers itself is rarely carried out in China.

The potato glycemic index is an index that comprehensively evaluates the degree of absorption and utilization of carbohydrates in potato tubers by the human body, and is also an important index to evaluate the nutritional quality of potatoes. The invention provides a method for measuring the glycemic index in potato. The method has simple measuring process, rapid analysis process and high accuracy, and can be used for screening low-glycemic potato varieties.

Related literature:

Trends in Food Science&Technology, 2014, 35(1):32-41.

Critical Reviews in Food Science and Nutrition, 2016, 56(2): 215-236.

Clinical Nutrition, 2020, 40(4): 2200-2209

SUMMARY OF THE INVENTION

In view of the above-mentioned technical problems, the present invention provides a method for measuring the glycemic index in potato, and the method for measuring comprises the following steps:

(1) Making with reference to the blood sugar response curve of food: measure the fasting blood sugar content, measure the fasting blood sugar for the second time after 10 minutes, eat 25 grams of glucose, record the time of eating the first mouth of glucose as 0min, supplemented with water, respectively, after eating Fingertip blood glucose levels were measured at 15, 30, 45, 60, 90 and 120 minutes after completion;

(2) Preparation of the blood sugar response curve of potato: the tubers of the tested potato varieties were cleaned and peeled, sliced, steamed, and placed at room temperature for 10 minutes, and the eating weight was a cooked potato containing 25 g of available carbohydrates;

(3) Determination of glycemic index of potato: Calculate the glycemic index of potato according to the following formula:

GIt=At×100/Aref

Among them, At is the area under the blood glucose response curve of the test food; Aref is the area under the blood glucose response curve of the reference food;

Calculate the average value of the GIt of each individual tested, expressed as the mean ± standard deviation, that is, the glycemic index GI of potato.

Preferably, each test subject described in step (1) has completed at least three repeated standard food reference experiments in the entire test cycle.

The second object of the present invention is to provide the application of the method for measuring the glycemic index of potato in screening low-glycemic potato varieties.

The beneficial effects of the present invention are as follows: the present invention provides a method for measuring the glycemic index in potato, the method has simple measurement process, rapid analysis process and high accuracy; the method for measuring the glycemic index in vivo according to the present invention , the measurement results are consistent with the results obtained by the existing in vitro measurement methods, indicating that the method for the in vivo glycemic index of the present invention has reference and can obtain accurate glycemic index values. At the same time, the blood glucose meter used in the present invention is a household blood glucose measuring instrument, which is simple and easy to operate; the medicines used are commonly used analytical medicines in laboratories, which are easy to purchase and low in cost, and can be used for batch analysis of a large number of samples.

Description of drawings

Figure 1 Flow chart of screening method for potato varieties

Detailed ways

The protection scope of the present invention will be described in detail below with reference to specific embodiments, but it should be understood that the protection scope of the present invention is not limited by the following embodiments.

Glycemic Index (GI), also known as food glycemic index, refers to the percentage of the area under the blood glucose response curve in a certain period of time after eating food containing 50g/25g of available carbohydrates and eating the same amount of glucose. Characteristic reflection of different responses to blood glucose caused by human digestion and absorption.

In the following examples, V7 is a variety of potato, with a growth period of about 95 days, belonging to a medium-ripening variety, the plant is erect and lush, with many branches, the plant height is about 60-80 cm, and the growth stage is relatively weak; Broken, the color is light green, the stalk is thin and green, the corolla is white, the flowering period is short; each plant has 4-6 tubers, the tuber expands faster, the tuber is oval, the appearance is smooth, the bud eye is sparse, large The potato rate is high and the commodity is good.

In the following examples, Burbank is an American variety, which was introduced into my country by the Seed Bureau of the Ministry of Agriculture, and is a new variety for processing frozen French fries.

In the following examples, Atlantic (potato) has good edible quality and is suitable for fried potato chips. It was introduced into China by the Ministry of Agriculture and the Chinese Academy of Agricultural Sciences in 1978, and introduced into Shanxi Province in 2000. It takes 90 days from emergence to maturity. Tubers have a medium dormancy period and are storable.

In the following examples, the nutrient components of tubers were measured: the total starch of tubers was measured with reference to the enzymatic hydrolysis method in GB 5009.9-2016; the content of total soluble sugars was measured with reference to the anthrone-ethyl acetate method; the fast-digesting starch, slow-digesting starch and resistance of tubers were The starch determination procedure is the same as the in vitro glycemic index determination, wherein the sampling time points are the 0, 20, and 120 min of hydrolysis, fast digested starch = total starch - 0 min starch content, slow digested starch = total starch - 0 min starch content - fast digested starch, Resistant starch = total starch - fast-digesting starch - slow-digesting starch; for the determination of dietary fiber, refer to the enzymatic hydrolysis method in GB 5009.88-2014.

1. In vivo determination of potato glycemic index

1. Materials and sources

Materials: Different varieties of potatoes: V7, Burbank, Atlantic, Gannong No. 7, Jizhang No. 12, Longshu No. 7, Gannong Milk Sweet Potato, Xisen No. 6;

Blood glucose meters and blood glucose test strips were purchased from the reagent company.

Drugs: sodium acetate buffer, pancreatin, glucoamylase, glucose, potassium sodium tartrate, 3,5-dinitrosalicylic acid, sodium hydroxide, phenol, anhydrous ethanol, all purchased from the reagent company and available from the market can be purchased from the reagent company.

2. Method

(1) Standard food reference experiment

The participants finished eating before 10 o'clock the night before the experiment, and then fasted (a small amount of water can be added). On the day of the experiment, the blood glucose meter measured the fasting blood glucose level by taking the blood from the capillary tube of the fingertip. After 10 minutes, the second fasting blood glucose was measured, and then 25 grams of glucose (medical grade, anhydrous glucose) was quickly eaten, and the time for the first bite of food was recorded as 0min, supplemented with 200ml of water. Fingertip blood glucose levels were measured at 15, 30, 45, 60, 90 and 120 min after eating, respectively. Each test subject completed at least three replicates of the standard food reference experiment throughout the test cycle.

(2) Determination of glycemic index of potato

The tubers of the tested potato varieties were cleaned and peeled, cut into slices with a thickness of 1 cm vertically, and steamed in a steamer at 110 °C for 30 minutes. After they were cooked, the tubers were taken out and placed at room temperature for 10 minutes. All participants were fed uniformly. The blood sugar determination process is the same as the standard food reference test. The meal weight is cooked potatoes with 25 g of usable carbohydrates.

(3) Calculation of glycemic index

GIt=At×100/Aref

At the area under the blood glucose response curve of the test food

Aref area under the blood glucose response curve of the reference food

The final GI is the mean value of the GIt of each individual tested, expressed as mean ± standard deviation.

2. In vitro determination of potato glycemic index

1. Materials and sources

In vitro simulated digestion system; constant temperature shaker, vortex mixer, 50ml centrifuge tube, glass beads, sodium acetate buffer, trypsin, glucoamylase.

2. Method

(1) Sample preparation: Wash and peel the tubers of the tested potato varieties, cut them into slices with a thickness of 1 cm vertically, steam them in a steamer at 110°C for 30 minutes, take out the tubers after they are cooked, and place them at room temperature for 10 minutes. Freeze-dried under 0.12mBar vacuum at -50°C, grind the freeze-dried samples and pass through an 80-mesh sieve, and store the obtained freeze-dried powder in an ultra-low temperature refrigerator at -80°C.

(2) Determination of glycemic index in vitro: the reference food is glucose. Weigh 100 mg of anhydrous glucose and potato freeze-dried powder in 50 ml centrifuge tubes, add 4 ml of sodium acetate buffer (pH 5.2) and 1 ml of freshly prepared enzyme solution ( The volume ratio of 3260U/ml saccharification enzyme to 290U/ml pancreatin is 1:5), hydrolyzed at 37°C in a 200r/min constant temperature shaker, and the hydrolysis will start at the 0th, 15th, 30th, 45th, 60th, 90th and 120th minutes of hydrolysis on time. 100 μL of the mixture was taken from the system, and an equal volume of anhydrous ethanol was used to inactivate the enzyme, and the glucose content at each time point was determined by DNS method. The hydrolysis curve of the sample was drawn with the time as the abscissa and the glucose content as the ordinate, and the area under the curve (Incremental area under the curve, IAUC) was calculated.

Starch hydrolysis index (SHI) = sample IAUC×100/reference food IAUC

In vitro glycemic index (estimated glycemic index, eGI)=39.71+(0.549×SHI)

3. Analysis of results

In 2021, the in vivo glycemic index and in vitro glycemic index of 8 main potato varieties at home and abroad were analyzed in the Key Laboratory of Genetic Improvement and Germplasm Innovation of Gansu Province. The specific measurement process is as shown above. The screening process of sugar-type potato varieties is shown in Figure 1. Eight main varieties were analyzed in the Key Laboratory of Genetic Improvement and Germplasm Innovation of Gansu Province. The in vivo and in vitro measurement data are shown in Table 1. On the basis of the statistical analysis of the repeated values of the tested potato varieties, the in vivo glycemic index and the in vitro glycemic index of the tested materials were compared, and the low glycemic potato varieties with lower glycemic index were screened out with the double low as the standard. . After comprehensive analysis, it was screened that V7 was a potato variety with low glycemic index. The glycemic index in vivo was only 58.08, the glycemic index in vitro was 57.8, and the GI/eGI reached 1.005.

Table 1 Comparison of in vivo and in vitro assay results of 8 main cultivars

Note: The closer the GI/eGI value is to 1, the more reasonable the in vitro digestion program setting is, and the closer to the true value measured in vivo

To sum up, the present invention provides a method for measuring the glycemic index in potato, which has a simple measurement process, a rapid analysis process and high accuracy; the method for measuring the glycemic index in the The results are consistent with the results obtained by the existing in vitro measurement methods, indicating that the method for the in vivo glycemic index of the present invention has reference and can obtain accurate glycemic index values. At the same time, the blood glucose meter used in the present invention is a household blood glucose measuring instrument, which is simple and easy to operate; the medicines used are commonly used analytical medicines in laboratories, which are easy to purchase and low in cost, and can be used for batch analysis of a large number of samples.

Claims (3)

1. A method for determining the glycemic index of potatoes in vivo, comprising the steps of:

(1) and (3) making a blood glucose response curve of reference food: measuring the fasting blood glucose content, measuring the fasting blood glucose for the second time after 10 minutes, eating 25g of glucose, recording the time for eating the first mouth of glucose as 0min, and adding clear water to measure the fingertip blood glucose content at the 15 th, 30 th, 45 th, 60 th, 90 th and 120 th min after the food intake is finished;

(2) preparing a blood sugar response curve of the potato: washing and peeling tubers of the tested potato variety, slicing, steaming, standing at room temperature for 10min, and eating cooked potato containing 25g of available carbohydrate;

(3) determination of the glycemic index of potatoes: the glycemic index of potatoes was calculated according to the following formula:

GIt＝At×100/Aref

wherein At is the area under the blood glucose response curve of the test food; aref is the area under the glycemic response curve for the reference food;

the mean value of each of the tested individuals GIt was calculated and expressed as the mean value ± standard deviation, i.e., the glycemic index GI.

2. The method of claim 1, wherein each of the test subjects of step (1) performs at least three repetitions of a standard food reference test throughout the test period.

3. Use of the method of determining the in vivo glycemic index of potatoes of claim 1 to screen low glycemic potato varieties.

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