Method for analyzing and detecting fatty acid in litchi pulp

Abstract

The invention discloses a method for analyzing and detecting fatty acid in litchi pulp, and belongs to the technical field of component detection.The method comprises the following steps that S1, a fresh litchi sample is taken and peeled, and the taken pulp is ground through liquid nitrogen for standby application; s2, taking the litchi pulp sample obtained in the step S1, and adding petroleum ether; and S3, adding a potassium hydroxide and methanol mixed solution, performing methyl esterification for 1 hour, adding ultrapure water, centrifuging by a centrifugal machine, taking supernate, filtering, and detecting by using a gas chromatograph-mass spectrometer. According to the method for analyzing and detecting the fatty acid in the litchi pulp, the litchi pulp can be used as a raw material, and different types of fatty acid in the litchi pulp can be measured.

Description

Technical Field

[0001] The invention relates to the technical field of component detection, and in particular to a method for analyzing and detecting fatty acids in litchi pulp. Background Art

[0002] Lychee is colorful and delicious and has always been loved by people. In recent years, modern medicine, nutrition, phytochemistry and pharmacology have provided solid evidence for the medical and health functions of lychee, and its functional active ingredients are constantly being revealed. The study of the nutritional composition and function of the pulp shows that the pulp of lychee contains a large number of nutritional and functional components. According to the analysis data, every 100g of fresh lychee pulp contains 16.53g of sugar, 276kJ of energy, 0.83g of protein, 0.44g of fat, 0.44g of ash, 1.3g of dietary fiber, 5mg of calcium, 0.31mg of iron, 10mg of magnesium, 31mg of phosphorus, 171mg of potassium, 1mg of sodium, 0.07mg of zinc, 71.5mg of vitamin C, 0.011mg of thiamine, 0.065mg of riboflavin, 0.603mg of niacin, 0.1mg of vitamin B6, 14mg of total folic acid, 0.07mg of vitamin E, 0.007mg of tryptophan, 0.041mg of lysine, and 0.009mg of methionine. Eating 100g of lychee pulp a day can meet 2% to 4% of the daily needs of P, K, Fe, Zn and other elements. In addition to meeting people's needs for nutrients, lychee pulp has certain antioxidant activity. In addition to vitamin C and vitamin E, its antioxidant components also include polysaccharides and flavonoids such as proanthocyanidin A2 and colorless cyanidin. The extraction rate of antioxidant active polysaccharides in lychee pulp can reach 3.3%.

[0003] Fatty acids are an important component of dietary fat. The current determination methods are relatively complex, and there are many types and dosages of extracts, the steps are relatively cumbersome, and it is only a qualitative analysis stage. It is unable to give the definite components and specific contents, and it is impossible to obtain accurate data information. Absolute quantitative analysis and internal standard positioning of multiple standards are not performed during the detection process. It is limited to qualitative analysis of the types of fatty acid methyl esters that may exist, which makes the generated data inaccurate.

[0004] In order to fully develop and utilize the application value of litchi pulp, Hainan litchi pulp was used as the research object in this study, and the fatty acids in its fruit pulp were studied by gas chromatography-mass spectrometry, the characteristics of fatty acid accumulation in the pulp of mature litchi fruits were analyzed, and the fatty acid components and contents were compared and analyzed, aiming to fully explore the fatty acid resource information of litchi, which is of great significance to the breeding and processing of litchi varieties, and provide a basis for further development and utilization of litchi. 36 kinds of mixed fatty acids were used as internal standard positioning and quantitative control to obtain the contents of various fatty acid methyl esters. When analyzing the results, this technical invention used retention index normal alkane standards as references, and introduced retention index verification in the detection method on the basis of library retrieval to confirm the results and increase the reliability of the data. Summary of the invention

[0005] In order to solve the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for analyzing and detecting fatty acids in litchi pulp, which can use Hainan litchi pulp as raw material to measure different types of fatty acids in litchi pulp.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] A method for analyzing and detecting fatty acids in litchi pulp is provided, comprising the following steps:

[0008] S1: Take fresh litchi samples, peel them, grind the pulp with liquid nitrogen and set aside;

[0009] S2: taking the litchi pulp sample obtained in step S1, adding petroleum ether for extraction;

[0010] S3: Add potassium hydroxide and methanol mixture for methyl esterification, add ultrapure water, centrifuge, take the supernatant and filter it, and then use gas chromatography-mass spectrometry to detect it.

[0011] Furthermore, the ratio of the added amount of the litchi pulp sample and the potassium hydroxide methanol mixture is: 1 ml, 1.15 ml or 1.2 ml of the potassium hydroxide methanol mixture is added to each gram of the litchi pulp sample.

[0012] Furthermore, the volume ratio of the petroleum ether to the potassium hydroxide methanol mixture is 2:1, 1.5:1 or 1:1.

[0013] Furthermore, the potassium hydroxide-methanol mixed solution is prepared by adding 2% by mass of potassium hydroxide into a methanol solution.

[0014] Furthermore, the methyl esterification time is 1 h.

[0015] Furthermore, the volume ratio of ultrapure water to petroleum ether is 1:1.

[0016] Furthermore, the centrifugation condition is 10000 r / min for 5 min, and 0.22 μm micromembrane filtration is used.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The fatty acid analysis and detection method in litchi pulp exemplified in the present invention adds petroleum ether for extraction, uses a potassium hydroxide methanol mixture to methylate the litchi pulp, and uses a gas chromatography-mass spectrometer to detect, and finally analyzes to obtain a high-efficiency fatty acid analysis and detection technology method in litchi pulp, which provides basic technical support for the effective development and utilization of litchi. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0020] Figure 1 This is the chromatogram of the methyl esterified sample of litchi pulp;

[0021] Figure 2 This is the chromatogram of 36 fatty acid methyl ester standards;

[0022] Figure 3 This is a comparison chart of the spiked positioning of litchi pulp sample and 36 fatty acid mixtures;

[0023] Figure 4 This is the standard curve (fatty acid methyl esters detected in litchi pulp). DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] This embodiment provides a method for analyzing and detecting fatty acids in litchi pulp.

[0027] The samples were collected from Dafeng Farm in Chengmai, Hainan Province. The varieties collected were Feizishao, mature fresh fruits. After the collected fresh fruits were peeled, the pulp was taken out, added with liquid nitrogen and ground for later use.

[0028] Take 0.5g of litchi pulp sample, add 1ml petroleum ether (boiling range 60-90°C), add 0.5ml 2% potassium hydroxide methanol mixed solution, methylate for 1h, add 1ml ultrapure water, centrifuge at 10000r / min for 5min; take the upper layer, filter with 0.22μm micro-membrane, use gas chromatography-mass spectrometry to detect the fatty acid methyl ester content, use standard products for positioning comparison and then convert the actual fatty acid content.

[0029] As shown in Table 1, it is a comparison table of 36 fatty acid methyl esters.

[0030] Table 1 Comparison table of 36 fatty acid methyl esters

[0031]

[0032]

[0033] The results showed that in the comparative test of litchi pulp samples and 36 fatty acid standards, 1.89 mg / kg of myristic acid, 93.53 mg / kg of palmitic acid, 3.7 mg / kg of palmitoleic acid, 15.69 mg / kg of stearic acid, 31.75 mg / kg of oleic acid, 10.41 mg / kg of elaidic acid, 57.38 mg / kg of linoleic acid, 3.03 mg / kg of trans-linoleic acid, 56.19 mg / kg of linolenic acid, 4.2 mg / kg of γ-linolenic acid, 1.48 mg / kg of eicosenoic acid and 1.24 mg / kg of behenic acid were detected in litchi pulp.

[0034] It can be seen from the examples that the fatty acid content in litchi pulp is relatively high. In the litchi pulp detected by the technology of the present invention, the palmitic acid content is relatively high, followed by linoleic acid, linolenic acid, stearic acid, etc. This detection method provides basic theoretical support for the screening, application and development of litchi varieties.

[0035] Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for analyzing and detecting fatty acids in litchi pulp, characterized in that: The following steps are involved: S1: Take fresh litchi samples, peel them, grind the pulp with liquid nitrogen and set aside; S2: taking the litchi pulp sample obtained in step S1, adding petroleum ether for extraction; S3: Add potassium hydroxide and methanol mixture for methyl esterification, add ultrapure water, centrifuge, take the supernatant and filter it, and then use gas chromatography-mass spectrometry to detect it.

2. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The ratio of the added amount of litchi pulp sample and potassium hydroxide methanol mixture is: 1 ml, 1.15 ml or 1.2 ml of potassium hydroxide methanol mixture is added to each gram of litchi pulp sample.

3. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The volume ratio of the petroleum ether and potassium hydroxide methanol mixture is 2:1, 1.5:1 or 1:

1.

4. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The potassium hydroxide-methanol mixed solution is prepared by adding 2% by mass of potassium hydroxide into a methanol solution.

5. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The methyl esterification time is 1 h.

6. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The volume ratio of ultrapure water to petroleum ether is 1:

1.

7. The method for analyzing and detecting fatty acids in litchi pulp according to claim 1, characterized in that: The centrifugation condition was 10000 r / min for 5 min and 0.22 μm micromembrane filtration was used.

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