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Method for rapidly and nondestructively detecting moisture content and drying degree of green tea in drying process based on low-field nuclear magnetic resonance technology

A low-field nuclear magnetic resonance, drying process technology, used in the field of chemical analysis

Pending Publication Date: 2021-03-19
TEA RES INST CHINESE ACAD OF AGRI SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there are few studies on the application of low-field NMR technology in the field of tea, and there is no report on the application of transverse relaxation spectroscopy to the detection of moisture content in green tea during the drying process.

Method used

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  • Method for rapidly and nondestructively detecting moisture content and drying degree of green tea in drying process based on low-field nuclear magnetic resonance technology
  • Method for rapidly and nondestructively detecting moisture content and drying degree of green tea in drying process based on low-field nuclear magnetic resonance technology

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Effect test

Embodiment 1

[0024] 1 Experimental part

[0025] 1.1 Instruments and devices

[0026] ME103E electronic balance, Mettler-Toledo (Shanghai) Instrument Co., Ltd.; MesoMR23-060H-I low-field nuclear magnetic resonance analyzer, Suzhou Numei Analytical Instrument Co., Ltd.; 80 type electromagnetic cleaning machine, Yuyao City Yaojiangyuan Tea Tea Machine Co., Ltd.; 6CR-55 tea rolling machine, Zhejiang Shangyang Machinery Co., Ltd.; CS-90XZ baking machine, Quanzhou Changsheng Tea Machinery Co., Ltd.

[0027] 1.2 Materials and reagents

[0028] The fresh tea leaves were collected in Shengzhou City, Zhejiang Province in April 2020. The variety is Zhongcha 108, and the tenderness ranges from one bud and one leaf to one bud and two leaves. The specific processing technology is as follows: Spreading (indoor temperature 25°C-28°C, humidity 70%-80%, moisture content down to about 70%) → drum type finishing (leaf throwing amount 150 kg / h, 260°C, 75 s, the moisture content is about 47%) → kneading (30...

Embodiment 2

[0037] Embodiment 2: detect the sample to be tested

[0038] Weigh about 1g of the tea sample to be tested (dried for 35 min at the same drying temperature of 85°C above) and put it into the magnet coil, and optimize the low-field NMR detection conditions. The specific parameters for CPMG sequence analysis are: NMR type It is a permanent magnet, the frequency of the nuclear magnetic generator is 23 MHz, 90° pulse width P1: 10μs; 180° pulse width P2: 19.52μs; receiver bandwidth SW: 333.333 KHz; time delay DL1: 0.06524ms; analog gain RG1: 20 ;Digital gain DRG1: 3, preamplifier gain PRG: 3; control parameter RFD of start sampling time: 0.08ms, delay DL1: 0.06524ms; NECH: 2000, so that the sample signal is completely relaxed; Repeated sampling waiting time TW: 1000ms; set the number of repeated sampling NS: 64, carry out NMR signal acquisition, and obtain the CPMG attenuation spectrum of the sample, and invert the measured transverse relaxation time T2 frequency image through soft...

Embodiment 3

[0041] Embodiment 3: detect the sample to be tested

[0042] Weigh about 1g of the tea sample to be tested and put it into the magnet coil, and optimize the low-field NMR detection conditions. The specific parameters for CPMG sequence analysis are: the NMR magnetic type is a permanent magnet, and the NMR generator frequency is 23 MHz, 90° Pulse width P1: 10μs; 180° pulse width P2: 19.52 μs; receiver bandwidth SW: 333.333 KHz; delay DL1: 0.06524 ms; analog gain RG1: 20; digital gain DRG1: 3, preamp gain PRG: 3; The control parameters of the start sampling time RFD: 0.08ms, delay DL1: 0.06524 ms; NECH: 2000, so that the sample signal is completely relaxed; repeated sampling waiting time TW: 1000 ms; set the number of repeated sampling NS: 64, for nuclear magnetic resonance The signal is collected to obtain the CPMG attenuation spectrum of the sample, and the measured transverse relaxation time T2 frequency image is inverted by software to obtain the inversion spectrum, and the t...

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Abstract

The invention discloses a method for rapidly and nondestructively detecting the moisture content and the drying degree of green tea in the drying process based on a low-field nuclear magnetic resonance technology, and belongs to the technical field of chemical analysis. The method comprises the following steps: establishing a model equation of a low-field nuclear magnetic T2 relaxation spectrum total signal amplitude and tea sample moisture content: y = 8E-05x-0.0143 and a fitting degree R2 = 0.967, when detecting the moisture content of a tea sample to be detected in the drying process, firstly performing low-field nuclear magnetic resonance analysis on the tea sample to be detected and performing normalization processing to obtain the low-field nuclear magnetic T2 relaxation spectrum total signal amplitude, and substituting the low-field nuclear magnetic T2 relaxation spectrum total signal amplitude into the model equation, so that the moisture content of the tea sample to be detected is obtained. According to the method, the low-field nuclear magnetic resonance analysis technology is applied to the green tea drying process, non-destructiveness and non-invasiveness are achieved,physical damage and chemical pollution cannot be caused to a sample, and important technical support is provided for online detection and quality control of the moisture state of the tea in-process products.

Description

technical field [0001] The invention belongs to the technical field of chemical analysis, and in particular relates to a method for rapidly and nondestructively detecting the moisture content and drying degree of green tea in a drying process based on low-field nuclear magnetic resonance technology. Background technique [0002] Green tea is one of the six major tea categories in my country. It is also the tea category with the largest production and sales volume and the most advanced processing technology in China. According to different production techniques, it can be divided into fried green tea, baked green tea, steamed green tea and sun-dried green tea. According to the differences in the external characteristics of green tea aroma in type and smell, green tea is subdivided into different aroma types such as floral aroma, light fragrance, and chestnut aroma. The so-called tea fragrance is actually the unique fragrance type of tea formed by the combination of different ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N24/08
CPCG01N24/08
Inventor 杨艳芹袁海波江用文邓余良董春旺李佳滑金杰王近近
Owner TEA RES INST CHINESE ACAD OF AGRI SCI
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