Pretreatment method for measuring ecostoichiometric ratio of strawberry fruits

Abstract

The invention relates to the field of agricultural product analysis and detection, and discloses a pretreatment method for determining the ecostoichiometric ratio of strawberry fruits, which comprises the following steps: picking strawberry fruits as a sample, cleaning the sample, and freezing in a refrigerator; slicing the frozen sample; putting the cut sample into a freeze-drying machine for freeze-drying; crushing the cold-dried sample, and sieving to obtain sample powder; and loading the sample powder into a sample bag for subsequent detection. The problem of how to improve the pretreatment efficiency of the sample on the premise of not causing irreversible damage to the sample is solved. According to the method, the strawberry fruits are freeze-dried by using the freeze dryer, so that dehydration is thorough, the pretreatment efficiency of the strawberry fruits is improved, irreversible damage to samples is avoided, and the method has the advantages of being simple to operate, thorough in dehydration, capable of improving the accuracy of analysis and determination results and the like.

Description

Technical Field

[0001] The invention relates to the field of agricultural product analysis and detection, and in particular to a pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruits. Background Art

[0002] Ecological stoichiometry is the ratio between multiple chemical elements (mainly C, N, and P) in the process of ecological interaction between organisms, which can be used to express the balance relationship between multiple chemical elements. According to the ecological stoichiometric ratio of plant fruits, we can understand the utilization efficiency of nutrients and choose the appropriate fertilization method to improve the quality of plant fruits.

[0003] In the prior art, samples need to be pre-treated before testing. The samples are dried at high temperature and then crushed, sieved and naturally air-dried. The purpose is to ensure that the samples can be completely digested so that the test results can accurately display the C, N and P contents in the samples.

[0004] Drying is also called thermal drying. After the air is heated, the air heats the sample, and the evaporated water of the sample is carried away by the air and discharged. The speed of thermal drying cannot be too fast. If the drying speed is too fast, the sample surface will shrink, thereby reducing the drying speed. At the same time, the temperature of thermal drying cannot be too high, otherwise the sample will be irreversibly damaged. However, the low temperature and slow drying speed of thermal drying cause the problem of low efficiency. Moreover, the sample after drying is not completely dehydrated, so it is difficult to grind it and make it a uniform test sample.

[0005] The subsequent natural air drying process is not only time-consuming, but also fails to completely dehydrate the fruit, and also causes certain losses and unevenness in the crushing step. Therefore, the existing pre-treatment method for determining the C, N, and P contents in strawberry fruit needs to be improved. Summary of the invention

[0006] In view of the problem existing in the prior art: how to improve the efficiency of sample pretreatment without causing irreversible damage to the sample, the purpose of the present invention is to provide a pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit. By using a freeze dryer to cold-dry the strawberry fruit, not only is the dehydration thorough, but the pretreatment efficiency of the strawberry fruit is also improved, and irreversible damage to the sample will not be caused. The method has the advantages of simple operation, thorough dehydration, and improved accuracy of analysis and determination results.

[0007] To achieve the above object, the technical solution of the present invention is: A pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit comprises the following steps: S1: Pick strawberry fruits as samples, wash the samples and freeze them in a refrigerator; S2: Slice the frozen sample; S3: Place the cut samples into a freeze dryer for cold drying; S4: crushing the freeze-dried sample and sieving it to obtain sample powder; S5: Put the sample powder into a sample bag for subsequent testing.

[0008] The present invention is further configured as follows: in step S1, strawberry fruits with intact appearance and no damage are selected.

[0009] The present invention is further configured as follows: in step S1, a plurality of strawberry fruits with similar external dimensions are selected.

[0010] The present invention is further configured as follows: in step S1, the freezing temperature in the refrigerator is -25°C.

[0011] The present invention is further configured as follows: in step S1, the freezing time of the sample in the refrigerator is 30 minutes.

[0012] The present invention is further configured such that the thickness of the sample slice in step S2 does not exceed 2 mm.

[0013] The present invention is further configured as follows: in step S3, the temperature in the freeze dryer is set to -65°C.

[0014] The present invention is further configured as follows: in step S3, the sample is freeze-dried in a freeze dryer for 24 hours.

[0015] The present invention is further configured such that: the mesh diameter of the sieve in step S4 does not exceed 0.15 mm.

[0016] The present invention is further configured as follows: in step S4, the sample is crushed by pounding.

[0017] In summary, the beneficial effects achieved by the present invention are as follows: By using a freeze dryer to cold-dry the strawberry fruit samples, the sample dehydration time is shortened, the sample pretreatment efficiency is improved, and no irreversible damage is caused to the samples; on the other hand, the samples are thoroughly dehydrated by cold drying, and the final sample powder improves the accuracy of the analysis and measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0019] Figure 1The figure is a schematic flow chart of the pretreatment method for determining the eco-stoichiometric ratio in strawberry fruit in the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] It should be noted that the embodiments of the present invention and the features involved in the embodiments can be combined with each other without conflict. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] As attached Figure 1 As shown, a pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit comprises the following steps: S1: Pick strawberry fruits as samples, wash the samples and freeze them in a refrigerator.

[0023] Strawberry fruits can be obtained from greenhouses. In order to fully meet the number of samples required for the experiment, a sufficient amount of strawberry fruits must be picked at one time. When picking, a sufficient number of strawberry fruits with similar appearance and intact appearance must be selected as samples.

[0024] After picking, wash the same batch of samples with water, preferably purified water or distilled water. Drain the water quickly after washing, and freeze the samples in a laboratory refrigerator or other environment that can provide the required temperature of -25°C, and set the freezing time to 30 minutes.

[0025] S2: Slice the frozen sample.

[0026] After the sample is frozen, the sample is taken out and quickly cut into slices with a thickness of no more than 2 mm using a slicer or other equipment. The thickness of the slice should be as thin as possible under the conditions that the prior art can achieve. The thinner the slice, the more conducive it is for the moisture in the sample slice to separate from the sample in the subsequent steps, thereby achieving complete dehydration of the sample. Therefore, the thickness of the slice can also be set to, for example, 1.5 mm, 1 mm, 0.8 mm, 0.5 mm or even smaller according to the performance of the slicer.

[0027] S3: Place the cut samples into a freeze dryer for cold drying.

[0028] A freeze dryer is an existing device that can freeze a water-containing substance into a solid state first, and then sublimate the water in it from the solid state into a gaseous state to remove the water and preserve the substance. Freeze drying is a drying technology that uses the principle of sublimation. It is a process in which the substance to be dried is quickly frozen at a low temperature, and then the frozen water molecules are directly sublimated into water vapor and escape under a suitable vacuum environment. The product obtained by freeze drying is called a lyophilized product, and the process is called freeze drying. Lyophilized products are mostly porous and dry sponges, with a basically unchanged volume, and are very easy to dissolve in water and return to their original state.

[0029] Freeze drying not only shortens the dehydration time of the sample and improves the efficiency of pretreatment, but also prevents the cut sample from being denatured in physical, chemical and biological aspects to the greatest extent. In the present invention, the temperature in the freeze dryer is set to -65°C, and the sample needs to be frozen and dried in the freeze dryer for 24 hours.

[0030] S4: The freeze-dried sample is crushed and sieved to obtain sample powder.

[0031] After the sample is cooled and dried, it can be poured into a mortar and crushed by pounding, or other equipment such as a grinder can be used to crush the sample. The crushed sample powder is screened using a sieve with a mesh diameter not exceeding 0.15 mm to obtain a sample powder with a particle size of less than 0.15 mm.

[0032] S5: Put the sample powder into a sample bag for subsequent testing.

[0033] After the sample powder is put into the sample bag, the sample bag is sealed to avoid exposure to sunlight and moisture, and then it can be used to determine the C, N, and P content in strawberry fruit. Specifically, the potassium dichromate external heating method can be used to detect the organic carbon in the sample; the Kjeldahl nitrogen method can be used to determine the total nitrogen in the sample; and the molybdenum antimony colorimetric method can be used to detect the total phosphorus in the sample.

[0034] The implementation principle of the above embodiment is: The pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit adopts freeze-drying to cold-dry the strawberry fruit sample. Compared with thermal drying and natural air drying, the sample dehydration time is shortened under freeze-drying, which improves the pretreatment efficiency of the sample; at the same time, the sample is dehydrated thoroughly without causing irreversible damage to the sample. The final sample powder can improve the accuracy of the analysis and determination results of the C, N, and P contents in strawberry fruit.

[0035] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit, characterized in that: The following steps are involved: S1: Pick strawberry fruits as samples, wash the samples and freeze them in a refrigerator; S2: Slice the frozen sample; S3: Place the cut samples into a freeze dryer for cold drying; S4: crushing the freeze-dried sample and sieving it to obtain sample powder; S5: Put the sample powder into a sample bag for subsequent testing.

2. The pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: In step S1, strawberry fruits with intact appearance and no damage are selected.

3. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 2, characterized in that: In step S1, a plurality of strawberry fruits with similar appearance and size are selected.

4. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: In step S1, the freezing temperature in the refrigerator is -25°C.

5. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 4, characterized in that: In step S1, the sample is frozen in the refrigerator for 30 minutes.

6. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: The thickness of the sample slice in step S2 does not exceed 2 mm.

7. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: In step S3, the temperature in the freeze dryer is set to -65°C.

8. The pre-treatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 7, characterized in that: In step S3, the sample is freeze-dried in a freeze dryer for 24 hours.

9. The pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: The mesh diameter of the sieve in step S4 does not exceed 0.15 mm.

10. The pretreatment method for determining the ecological stoichiometric ratio in strawberry fruit according to claim 1, characterized in that: In step S4, the sample is crushed by pounding.

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