CN114034758A

CN114034758A - Method for identifying drying mode of dried vegetable product

Info

Publication number: CN114034758A
Application number: CN202111197482.0A
Authority: CN
Inventors: 宋娟; 康三江; 展宗冰; 张海燕; 袁晶
Original assignee: Agricultural Products Storage & Processing Institute Gansu Academy Of Agricultural Sciences
Current assignee: Agricultural Products Storage & Processing Institute Gansu Academy Of Agricultural Sciences
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2022-02-11

Abstract

The invention provides an identification method of a drying mode of a dried vegetable product, and relates to the field of food identification. The method comprises the steps of constructing a standard characteristic spectrum, constructing a characteristic spectrum of the dried vegetable product to be identified and identifying the drying mode of the dried vegetable product to be identified. The invention provides a novel identification technology, which aims to identify the drying mode of a dried vegetable product, presents a standard product of the dried vegetable product and volatile flavor substances in the dried vegetable product to be detected in a common drying mode based on the visualization of a gas-phase ion mobility spectrum, and is favorable for accurately confirming the drying mode of the dried vegetable product to be detected by comparing the gas-phase ion mobility spectrums of the product to be detected and the standard product. The identification method provided by the invention is simple and convenient to operate, high in detection efficiency and sensitivity, does not need pretreatment, is suitable for implementation and popularization, and has wide application prospects in the fields of food safety, food quality control and the like.

Description

Method for identifying drying mode of dried vegetable product

Technical Field

The invention relates to the field of food identification, in particular to an identification method of a drying mode of a dried vegetable product.

Background

The vegetable not only contains rich dietary fiber, multiple vitamins, calcium, iron, zinc and other mineral elements, but also has various phytochemicals capable of promoting human health, such as thioglucoside, flavone, ACSOs, flavanol, anthocyanin and other active substances, and has a series of health-care effects of being beneficial to human health, such as anti-cancer property, anti-platelet activity, anti-thrombosis activity, anti-asthma, anti-oxidation and the like. Because of the high moisture content in fresh vegetables, they are susceptible to spoilage during transportation and storage. With the rapid rise of the vegetable drying technology, the dried vegetable product inhibits the growth of microorganisms because most of moisture in materials is removed, is convenient to store and prolongs the shelf life, is a healthy and delicious convenience food and is deeply loved by consumers. In addition, due to the increasing health care awareness of consumers, food processing enterprises are receiving a high attention to the quality of dried vegetable products prepared by different drying methods.

The method for identifying the drying mode of the dried vegetable products has the advantages that the volatile flavor substances of the dried vegetable products in different drying modes are obviously different, the drying mode is not identified quickly, the traditional method for identifying the drying mode of the dried vegetable products mainly depends on human senses, the comprehensive evaluation accuracy is high, the method is easily influenced by subjectivity, the standard definition is fuzzy, the quantitative basis is lacked, in addition, the period of identifying personnel who cultivate specialties is long, and the large-batch identification work cannot be carried out, so that the method for identifying the drying mode of the dried vegetable products quickly and accurately without complex pretreatment is especially important to explore.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects that the identification method of the dried vegetable product drying mode in the prior art is strong in subjectivity, lack of quantitative basis and incapable of realizing large-scale identification work, thereby providing the identification method of the dried vegetable product drying mode based on the gas phase ion mobility spectrometry (GC-IMS) technology.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides an identification method of a drying mode of a dried vegetable product, which comprises the following steps:

(1) constructing a standard characteristic map: selecting dried vegetable product standard products prepared by different drying modes, and detecting volatile organic compounds in each standard product by adopting a gas phase ion mobility spectrometry combined instrument to obtain a gas phase ion mobility spectrometry of the standard product as a standard characteristic spectrum of the dried vegetable product standard product;

(2) constructing a characteristic spectrum of the dried vegetable product to be identified: detecting volatile organic compounds in the dried vegetable products to be identified by adopting a gas-phase ion mobility spectrometry instrument to obtain a gas-phase ion mobility spectrometry of the dried vegetable products to be identified, wherein the gas-phase ion mobility spectrometry is used as a characteristic chromatogram of the dried vegetable products to be identified;

(3) and (3) identifying the drying mode of the dried vegetable product to be identified: comparing the characteristic spectrum of the dried vegetable product to be identified obtained in the step (2) with the standard characteristic spectrum obtained in the step (1), and judging that the dried vegetable product to be identified and the standard product of the type have the same drying mode if the matching degree of the characteristic spectrum of the dried vegetable product to be identified and the spectrum of the standard product of the type in the standard characteristic spectrum in an analysis area is more than 80%.

Further, the dried vegetable product standard comprises: hot air drying standard, solar drying standard and vacuum freeze drying standard.

Further, in the step of drying the standard product by hot air, the temperature of a drying oven for hot air drying is 40-50 ℃, and the air speed is 1-1.5 m/s;

in the drying step of the solar drying standard product, day and night continuous drying is carried out in a solar drying workshop, the temperature is 20-50 ℃, and the wind speed is 1-2 m/s;

in the drying step of the vacuum freeze-drying standard product, a vacuum freeze-dryer is used for drying, the temperature of a cold trap is-59.3 to-62.7 ℃, and the vacuum degree is not more than 1.0 Pa.

Further, in the drying steps of the hot air drying standard product, the solar drying standard product and the vacuum freeze drying standard product, the vegetables are dried until the moisture content of the vegetables is lower than 6-8%, or the mass change of the vegetables is not more than 1g every half hour.

Further, the detection conditions of the gas phase ion mobility spectrometry instrument are as follows:

the headspace sample injection volume is 450-650 mu L, the incubation time is 15-20 min, the incubation temperature is 40-60 ℃, the sample injection needle temperature is 65-85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 15-30 min, and the column temperature is 55-65 ℃; the carrier gas/drift gas is high-purity nitrogen, the temperature of an IMS detector is 40-50 ℃, the drift gas flow rate is 150mL/min, and the gas phase carrier gas flow rate is as follows: keeping the temperature at 2mL/min for 2min, increasing the temperature to 10mL/min within 8min, and increasing the temperature to 100-150 mL/min within 10 min.

the headspace sample injection volume is 450-550 mu L, the incubation time is 15-20 min, the incubation temperature is 40-45 ℃, the sample injection needle temperature is 80-85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 25-30 min, and the column temperature is 55-60 ℃; the carrier gas/drift gas is high-purity nitrogen, the temperature of an IMS detector is 40-45 ℃, the drift gas flow rate is 150mL/min, and the gas phase carrier gas flow rate is as follows: keeping the temperature at 2mL/min for 2min, increasing the temperature to 10mL/min within 8min, and increasing the temperature to 100-150 mL/min within 10 min.

Further, in the step (1), the preparation method of the various dried vegetable product standard products comprises the following steps: the vegetable is sequentially washed and cut, color-protected hot-ironed, cooled and drained and dried.

Further, the color protection blanching is to immerse the cleaned and cut vegetables into sodium bicarbonate color protection liquid for blanching with boiling water, wherein the concentration of the sodium bicarbonate color protection liquid is 1-5 per mill, the pH value is 5-9, and the blanching time with boiling water is 30-60 s.

Furthermore, the concentration of the sodium bicarbonate color protection solution is 2-4 per mill, the pH value is 6-8, and the time of blanching in boiling water is 30-45 s.

Further, the dried vegetable product is a dried product of spinach, cabbage, onion, cherry tomato or pleurotus eryngii.

The technical scheme of the invention has the following advantages:

the invention provides a novel identification technology, aims to identify the drying mode of a dried vegetable product, visually presents a standard product of the dried vegetable product and volatile flavor substances in the dried vegetable product to be detected in a common drying mode based on gas chromatography-ion mobility spectrometry (GC-IMS), and is favorable for accurately confirming the drying mode of the dried vegetable product to be detected by comparing the gas phase ion mobility spectrometry of the dried vegetable product to be detected and the standard product. The identification method provided by the invention is simple and convenient to operate, high in detection efficiency and sensitivity, does not need pretreatment, is suitable for implementation and popularization, and has wide application prospects in the fields of food safety, food quality control and the like. In addition, the identification method can ensure the standardization and the standardization of the preparation method of the dried vegetable products, and has important theoretical and practical significance for modifying and perfecting the industrial standard of the dried vegetable products, supervising the production behavior of production enterprises, ensuring the authenticity of product drying mode labels, protecting enterprise brands, ensuring the rights and interests of consumers, standardizing the healthy development of the market of the dried vegetable products and the like.

The reliability of the identification method is checked by combining a Principal Component Analysis (PCA) technology, and researches show that the dried vegetable products with different drying modes can be clustered by adopting a gas-phase ion mobility spectrometry, wherein fresh vegetables, the dried vegetable products prepared by adopting a vacuum freeze drying mode and the dried vegetable products prepared by adopting a hot air drying/solar drying mode can be obviously distinguished, while the similarity of volatile components in the dried vegetable products prepared by adopting the hot air drying and solar drying modes is very high and cannot be obviously distinguished, but the similarity of volatile flavor substances based on the two volatile flavor substances is just proved, and the distinguishing significance of the two drying modes is not great. According to the method, related experiments are carried out by taking spinach, cabbage, onion, cherry tomato and pleurotus eryngii as research objects, similar laws are found, repeated experiments prove that the method is suitable for identifying most dried vegetable products in a common drying mode and has universality.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a gas phase ion mobility spectrum of a fresh spinach sample and various dried product standards according to example 1 of the present invention;

FIG. 2 is a diagram showing the analysis of main components of a fresh spinach sample and various dried spinach standards according to example 1 of the present invention;

FIG. 3 is the gas phase ion mobility spectrum of the fresh cabbage sample and various dried product standards in example 2 of the present invention;

FIG. 4 is a diagram showing the analysis of main components of fresh cabbage and various dried product standards in example 2 of the present invention;

FIG. 5 is a gas phase ion mobility spectrum of fresh onion and various dried product standards according to example 3 of the present invention;

FIG. 6 is a diagram showing the analysis of main components of fresh onion specimens and various dried product standards in example 3 of the present invention;

FIG. 7 is a gas phase ion mobility spectrum of fresh cherry tomato samples and various dried product standards according to example 4 of the present invention;

FIG. 8 is a graph showing the analysis of the main components of the fresh cherry tomato sample and various dried product standards according to example 4 of the present invention;

FIG. 9 is a gas phase ion mobility spectrum of fresh Pleurotus eryngii sample and various dried product standards in example 5 of the present invention;

FIG. 10 is a diagram showing the analysis of the main components of fresh Pleurotus eryngii samples and various dried product standards in example 5 of the present invention.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

Spinach, cabbage, onion, cherry tomato and pleurotus eryngii adopted in the embodiments of the invention are fresh vegetable samples purchased from the city of the Lanzhou city of Gansu province; sodium bicarbonate (food grade) was purchased from chemical products limited, huayue, hannan; dried spinach products, dried onion products and dried pleurotus eryngii products to be identified are all purchased from Gansu Jinsha food Co., Ltd, and the samples are obtained by adopting a hot air drying mode; dried cabbage products and dried cherry tomato products to be identified are purchased from Tianzhu vegetable vacuum freeze-dried food Co., Ltd, and the samples are obtained by adopting a vacuum freeze-drying mode.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The raw materials or equipment used are all conventional products which can be obtained commercially, including but not limited to the raw materials or equipment used in the examples of the present application.

Example 1

The embodiment provides an identification method of a drying mode of a dried spinach product, which comprises the following steps:

1. constructing a standard characteristic map:

(1) preparation of dried spinach product standard product

a. Cleaning and cutting: the roots and pedicles of fresh spinach were removed, washed and cut into 20mm pieces.

b. Color protection and hot ironing: and soaking the cut spinach into sodium bicarbonate color protection solution with the concentration of 4 per mill and the pH value of 7 to be blanched in boiling water for 30 s.

c. Cooling and draining: the blanched spinach was quickly cooled and the surface water was drained.

d. And (3) drying: uniformly spreading the drained spinach into a single layer, respectively carrying out hot air drying, solar energy drying and vacuum freeze drying to obtain a hot air drying standard product, a solar energy drying standard product and a vacuum freeze drying standard product, wherein,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 40 ℃, and the air speed is 1 m/s;

in the drying step of the solar drying standard product, continuous day and night drying is carried out in a solar drying workshop, the temperature is 20-50 ℃, and the wind speed is 1 m/s;

in the drying step of vacuum freeze drying of the standard product, a vacuum freeze dryer is used for drying, the temperature of a cold trap is-60.7 to-61.3 ℃, and the vacuum degree is 1.0 Pa;

during the drying process of hot air drying standard, solar drying standard and vacuum freeze drying standard, the moisture content is measured every half hour, and the spinach is dried until the moisture content is lower than 8% (the mass change is not more than 1g every half hour).

e. And (3) sterilizing and packaging: and sterilizing and packaging the dried spinach product to obtain a hot air drying standard product, a solar drying standard product and a vacuum freeze drying standard product respectively.

(2) Gas phase ion mobility spectrometry detection

By using Flavour

The method comprises the steps of detecting volatile organic compounds in each standard by a gas phase ion mobility spectrometry instrument, taking fresh spinach samples as a reference, and making 3 samples in parallel to obtain gas phase ion mobility spectrometry of the standard, wherein the fresh spinach samples are respectively marked as B1-1, B1-2 and B1-3, the hot air drying standard is respectively marked as B2-1, B2-2 and B2-3, the solar drying standard is respectively marked as B3-1, B3-2 and B3-3, and the vacuum freeze drying standard is respectively marked as B4-1, B4-2 and B4-3, and are used as a standard characteristic spectrum of a dried spinach product standard as shown in figure 1.

The detection conditions of the gas phase ion mobility spectrometry instrument are as follows:

the headspace sample injection volume is 500 mu L, the incubation time is 15min, the incubation temperature is 40 ℃, the sample injection needle temperature is 85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 30min, and the column temperature is 60 ℃; the carrier gas/drift gas is high-purity nitrogen (purity is more than or equal to 99.999%), the IMS detector temperature is 45 ℃, the drift gas flow rate (E1) is 150mL/min, and the gas phase carrier gas flow rate (E2) is as follows: 2mL/min is maintained for 2min, and is increased to 10mL/min within 8min and to 150mL/min within 10 min.

2. Constructing a characteristic spectrum of the dried spinach product to be identified:

by using Flavour

And detecting volatile organic compounds in the dried spinach product to be identified by a gas-phase ion mobility spectrometry instrument to obtain a gas-phase ion mobility spectrometry of the dried spinach product to be identified, wherein the gas-phase ion mobility spectrometry is used as a characteristic spectrum of the dried spinach product to be identified, and the detection condition of the gas-phase ion mobility spectrometry instrument is consistent with that of the standard substance.

3. And (3) identifying the drying mode of the dried spinach product to be identified:

and comparing the characteristic spectrum of the dried spinach product to be identified with the standard characteristic spectrum, and judging that the dried spinach product to be identified is the same as the standard product in the same drying mode if the matching degree of the characteristic spectrum of the dried spinach product to be identified and the standard product in the standard characteristic spectrum in the analysis region is more than 80%.

4. Principal component analysis and detection result analysis

(1) Principal component analysis

By using Flavour

Dynamic principal component analysis was performed on the Dynamic PCA plug-in of the gas phase ion mobility spectrometry instrument, and the results of clustering the spinach fresh sample, the hot air drying standard, the solar drying standard and the vacuum freeze drying standard are shown in FIG. 2.

The contribution rate of the spinach main component PC1 is 76%, the contribution rate of the PC2 is 21%, the cumulative contribution rate of the 2 main components is up to 97%, and the difference of the types of the volatile organic compounds after the spinach is treated by different drying modes is obvious (P < 0.05). The distances between the hot air drying and the solar drying of the spinach dried products are similar, which shows that the difference of the flavor substances of the samples after the hot air drying and the solar drying is smaller, and shows that the effects of the two drying modes are basically consistent. Furthermore, hot air drying can be clearly distinguished from solar drying of dried spinach and fresh, vacuum freeze-dried spinach. The method provided by the invention can be used for identifying the drying mode of the dried spinach product.

(2) Analysis of detection results

a. Standard feature profile analysis

As shown in figure 1, qualitative analysis is carried out on volatile components based on gas chromatography retention time and ion migration time of volatile substances, 105 volatile substances are generated in a dried spinach product, comparison is carried out according to an existing database, 26 known components and 79 unknown components are determined, wherein the volatile substances of the dried spinach product which are qualitatively detected are mainly 8 types (accounting for 30.77 percent) of aldehydes, 7 types (accounting for 26.92 percent) of ketones, 3 types (accounting for 11.54 percent) of alcohols, 3 types (accounting for 11.54 percent) of esters, 3 types (accounting for 11.54 percent) of heterocycles, and 2 types (accounting for 7.69 percent) of terpenes, and the content of the aldehyde substances is relatively highest. As can be seen from FIG. 1, most of the flavor substances contained in the spinach in a fresh state are obviously reduced or disappeared after being dried, and the main substances comprise characteristic volatile organic compounds such as 3-pentanone, phenylacetaldehyde, methyl benzoate, 2-butanone and ethyl acetate, and the concentration of the characteristic volatile organic compounds is obviously higher than that of the samples in other states. After the spinach is treated by different drying modes, the types of volatile organic matters are obviously increased, and new volatile organic matters appear. For example, the spinach has the characteristic volatile organic compounds of acetone, isovaleraldehyde, 2-ethylfuran, n-hexanal, 2-hexenol, ethanol, benzaldehyde, methyl heptenone, 2-pentylfuran, valeraldehyde and the like during hot air drying and solar drying, and the spinach has the characteristic volatile organic compounds of dipentene during vacuum freeze drying, and the concentration of the dipentene is obviously higher than that of the samples in other states.

The types of volatile organic compounds measured in FIG. 1 are explained as follows: the volatile organic compounds are numbered from left to right and are numbers 1-105 in sequence, and compared according to the existing database, 26 known components are: no. 3 is 3-pentanone, No. 6 is phenylacetaldehyde, No. 7 is methyl benzoate, No. 10 is 2-butanone monomer, No. 11 is 2-butanone dimer, No. 12 is ethyl acetate monomer, No. 13 is ethyl acetate dimer, No. 14 is ethanol, No. 16 is acetone, No. 20 is isovaleraldehyde, No. 27 is 2-ethylfuran dimer, No. 28 is 2-ethylfuran monomer, No. 30 is n-hexanal dimer, No. 31 is n-hexanal monomer, No. 35 is 2-hexenol monomer, No. 36 is 2-hexenol dimer, No. 40 is benzaldehyde monomer, No. 41 is benzaldehyde dimer, No. 48 is cyclohexanone, No. 49 is 2-heptanone, No. 53 is methylheptenone, No. 54 is 2-ethylfuran, No. 61 is valeraldehyde monomer, No. 62 is valeraldehyde dimer, No. 103 is dipentene monomer, No. 104 is dipentene dimer, the remaining numbers are 79 unknown components.

b. Analysis of discrimination results

The characteristic spectrum of the dried spinach product to be identified is compared with the standard characteristic spectrum, the matching degree of the characteristic spectrum of the dried spinach product to be identified and the spectrum of the hot air drying standard product in the standard characteristic spectrum in an analysis area is highest and reaches more than 80 percent, so that the dried spinach product to be identified is judged to be obtained in a hot air drying mode based on the method provided by the embodiment and is consistent with the product information when the sample is purchased, and the method provided by the embodiment is proved to be used for identifying the drying mode of the dried spinach product and to have reliable identification results.

Example 2

The embodiment provides an identification method of a drying mode of a dried cabbage product, which comprises the following steps:

1. constructing a standard characteristic map:

(1) preparation of dried cabbage product standard

a. Cleaning and cutting: removing inedible part of fresh caulis et folium Brassicae Capitatae, cleaning, and cutting into blocks of 20mm × 20 mm.

b. Color protection and hot ironing: and soaking the cut cabbage into sodium bicarbonate color protection solution with the concentration of 2 per mill and the pH value of 4 for blanching in boiling water for 40 s.

c. Cooling and draining: and (4) rapidly cooling the blanched cabbage, and draining off surface water.

d. And (3) drying: uniformly spreading the drained cabbage into a single layer, respectively performing hot air drying, solar energy drying and vacuum freeze drying to obtain a hot air drying standard product, a solar energy drying standard product and a vacuum freeze drying standard product, wherein,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 45 ℃, and the air speed is 1.5 m/s;

in the drying step of the solar drying standard product, continuous day and night drying is carried out in a solar drying workshop, the temperature is 20-50 ℃, and the wind speed is 1.5 m/s;

in the drying step of vacuum freeze drying of the standard product, a vacuum freeze dryer is used for drying, the temperature of a cold trap is-59.3 to-60.7 ℃, and the vacuum degree is 1.0 Pa;

in the drying process of hot air drying standard products, solar drying standard products and vacuum freeze drying standard products, the moisture content is measured every half hour, and the cabbage is dried until the moisture content is lower than 8% (the mass change is not more than 1g every half hour).

e. And (3) sterilizing and packaging: and sterilizing and packaging the dried cabbage product to obtain a hot air drying standard product, a solar drying standard product and a vacuum freeze drying standard product respectively.

(2) Gas phase ion mobility spectrometry detection

By using Flavour

The method comprises the steps of detecting volatile organic compounds in each standard by a gas-phase ion mobility spectrometry instrument, taking fresh cabbage samples as a reference, and performing 3 parallel analysis on each sample to obtain a gas-phase ion mobility spectrometry of the standard, wherein the fresh cabbage samples are respectively marked as G1-1, G1-2 and G1-3, the hot air drying standard is respectively marked as G2-1, G2-2 and G2-3, the solar drying standard is respectively marked as G3-1, G3-2 and G3-3, and the vacuum freeze drying standard is respectively marked as G4-1, G4-2 and G4-3, as shown in figure 3.

the headspace sample injection volume is 500 mu L, the incubation time is 20min, the incubation temperature is 40 ℃, the sample injection needle temperature is 80 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 25min, and the column temperature is 55 ℃; the carrier gas/drift gas is high-purity nitrogen (purity is more than or equal to 99.999%), the IMS detector temperature is 40 ℃, the drift gas flow rate (E1) is 150mL/min, and the gas phase carrier gas flow rate (E2) is as follows: 2mL/min is maintained for 2min, and is increased to 10mL/min within 8min and to 150mL/min within 10 min.

2. Constructing a characteristic spectrum of the dry cabbage product to be identified:

by using Flavour

And detecting volatile organic compounds in the cabbage dry product to be identified by using the gas-phase ion mobility spectrometry instrument to obtain a gas-phase ion mobility spectrometry of the cabbage dry product to be identified, wherein the gas-phase ion mobility spectrometry is used as a characteristic spectrum of the cabbage dry product to be identified, and the detection condition of the gas-phase ion mobility spectrometry instrument is consistent with that of the standard substance.

3. And (3) identifying the drying mode of the dry cabbage product to be identified:

and comparing the characteristic spectrum of the dry cabbage product to be identified with the standard characteristic spectrum, and judging that the dry cabbage product to be identified and the standard product in the same drying mode if the matching degree of the characteristic spectrum of the dry cabbage product to be identified and the standard product in the standard characteristic spectrum in the analysis region is more than 80%.

4. Principal component analysis and detection result analysis

(1) Principal component analysis

By using Flavour

Dynamic principal component analysis is carried out on the Dynamic PCA plug-in of the gas phase ion mobility spectrometry instrument, and a fresh cabbage sample, a hot air drying standard substance, a solar drying standard substance and a vacuum freeze drying standard substance are clustered, and the result is shown in FIG. 4.

The contribution rate of the main component PC1 of the cabbage is 72%, the contribution rate of the PC2 is 22%, the cumulative contribution rate of the 2 main components is up to 94%, and the difference of the types of the volatile organic compounds after the cabbage is treated by different drying modes is obvious (P < 0.05). The distances between the hot air drying and the solar drying are similar, which shows that the flavor substance difference of the sample after the hot air drying and the solar drying is smaller, and shows that the effects of the two drying modes are basically consistent. In addition, hot air drying can be obviously distinguished from solar drying of dried cabbage products and fresh-like, vacuum freeze-dried, dried cabbage products. The method provided by the invention can be used for identifying the drying mode of the dried cabbage product.

(2) Analysis of detection results

a. Standard feature profile analysis

As shown in fig. 3, qualitative analysis is performed on volatile components based on gas chromatography retention time and ion migration time of volatile substances, 91 volatile substances are generated in the dry cabbage product, 37 known components and 54 unknown components are determined by comparison according to an existing database, wherein the qualitatively detected volatile substances, which constitute the dry cabbage product, mainly comprise 9 types of ketones (24.32%), 8 types of esters (21.62%), 8 types of alcohols (21.62%), 6 types of aldehydes (16.22%), 3 types of esters (11.54%), 3 types of heterocycles (11.54%), 2 types of acids (5.41%), and 2 types of terpenes (5.41%), and the content of the ketones is relatively highest. As can be seen from fig. 3, most of the flavor substances contained in the fresh cabbage are obviously reduced or disappeared after being treated in a drying manner, the main substances include characteristic volatile organic compounds such as folic alcohol acetate, cis-3-hexen-1-ol, 3-pentanone, 3-octanone and the like, and the concentration of the characteristic volatile organic compounds is obviously higher than that of the characteristic volatile organic compounds in the samples in other states; before and after the cabbage is treated by different drying modes, the types of volatile organic matters such as n-amyl alcohol, methyl benzoate and the like are not obviously different; after the cabbage is treated by different drying modes, the types of volatile organic compounds are obviously increased, and new volatile organic compounds appear. For example, the characteristic volatile organic compounds of the cabbage in hot air drying and solar drying are mainly 2-butanone, gamma-butyrolactone, 2-heptanone, heptane, butanedione, valeraldehyde, butyric acid, etc., and the characteristic volatile organic compounds of the cabbage in vacuum freeze drying are mainly 2-ethylhexanol, 2-methylbutanol, ethyl acetate, n-hexanal, benzaldehyde, dipentene, cyclohexanone, etc., and the concentration thereof is significantly higher than that in the sample in other states.

The types of volatile organic compounds measured in FIG. 3 are explained as follows: the volatile organic compounds are numbered from left to right in turn from No. 1 to No. 91, and are compared according to the existing database, and the known components are 37: no. 7 is a geranyl acetate monomer, No. 8 is a geranyl acetate dimer, No. 12 is a cis-3-hexen-1-ol dimer, No. 13 is a geranyl acetate monomer, No. 14 is n-hexanol, No. 16 is a 3-pentanone dimer, No. 17 is a 3-pentanone monomer, No. 19 is 3-octanone, No. 23 is n-pentanol, No. 25 is methyl benzoate, No. 26 is ethanol, No. 27 is acetone, No. 32 is 2-butanone, No. 39 is a γ -butyrolactone dimer, No. 40 is a γ -butyrolactone monomer, No. 50 is 2-heptanone, No. 52 is 3-hydroxy-2-butanone, No. 56 is a heptane dimer, No. 57 is a heptane monomer, No. 60 is butanedione, No. 65 is a pentanal monomer, No. 66 is a pentanal dimer, No. 67 is a butyric acid dimer, No. 68 is a butyric acid monomer, No. 73 is a 2-methylbutanol monomer, no. 74 is 2-methylbutanol dimer, No. 78 is ethyl acetate dimer, No. 79 is ethyl acetate monomer, No. 80 is n-hexanal monomer, No. 81 is n-hexanal dimer, No. 82 is benzaldehyde monomer, No. 83 is benzaldehyde dimer, No. 84 is dipentene monomer, No. 85 is dipentene dimer, No. 88 is cyclohexanone, No. 90 is 2-ethylhexanol monomer, No. 91 is 2-ethylhexanol dimer, and the remaining numbers are 54 unknown components.

b. Analysis of discrimination results

The characteristic spectrum of the dry cabbage product to be identified is compared with the standard characteristic spectrum, the matching degree of the characteristic spectrum of the dry cabbage product to be identified and the spectrum of the vacuum freeze-drying standard product in the standard characteristic spectrum in an analysis area is the highest and reaches more than 80%, therefore, the method provided by the embodiment is used for judging that the dry cabbage product to be identified is obtained in a vacuum freeze-drying mode and is consistent with product information when a sample is purchased, and the method provided by the embodiment is proved to be used for identifying the drying mode of the dry cabbage product, and the identification result is reliable.

Example 3

The embodiment provides an identification method of a dried onion product drying mode, which comprises the following steps:

1. constructing a standard characteristic map:

(1) preparation of dried onion product standard product

a. Cleaning and cutting: the skin and root pedicle of fresh onion were removed, washed, and cut into 30mm × 30mm pieces.

b. Color protection and hot ironing: soaking the cut onion in sodium bicarbonate color protection solution with the concentration of 4 per mill and the pH value of 8 to blanching in boiling water for 45 s.

c. Cooling and draining: quickly cooling the scalded onion, and draining off surface water.

d. And (3) drying: uniformly spreading the drained onions into a single layer, respectively performing hot air drying, solar energy drying and vacuum freeze drying to obtain a hot air drying standard product, a solar energy drying standard product and a vacuum freeze drying standard product, wherein,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 40 ℃, and the air speed is 1.5 m/s;

in the drying step of vacuum freeze drying of the standard product, a vacuum freeze dryer is used for drying, the temperature of a cold trap is-60.6 to-61.9 ℃, and the vacuum degree is 1.0 Pa;

in the drying process of hot air drying standard products, solar drying standard products and vacuum freeze drying standard products, the moisture content is measured every half hour, and the drying is carried out until the moisture content of the onion is lower than 8% (the mass change is not more than 1g every half hour).

e. And (3) sterilizing and packaging: and sterilizing and packaging the dried onion product to obtain a hot air drying standard product, a solar drying standard product and a vacuum freeze drying standard product respectively.

(2) Gas phase ion mobility spectrometry detection

By using Flavour

Detecting volatile organic compounds in each standard by gas phase ion mobility spectrometry, taking fresh onion samples as reference, making 3 samples of each sample in parallel,and obtaining a gas phase ion mobility spectrometry of the standard, and taking the obtained gas phase ion mobility spectrometry as a standard characteristic chromatogram of the dried onion product, wherein the fresh onion samples are respectively marked as Y1-1, Y1-2 and Y1-3, the hot air drying standard is respectively marked as Y2-1, Y2-2 and Y2-3, the solar drying standard is respectively marked as Y3-1, Y3-2 and Y3-3, and the vacuum freeze drying standard is respectively marked as Y4-1, Y4-2 and Y4-3, as shown in figure 5.

the headspace sample injection volume is 500 mu L, the incubation time is 15min, the incubation temperature is 45 ℃, the sample injection needle temperature is 85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 30min, and the column temperature is 60 ℃; the carrier gas/drift gas is high-purity nitrogen (purity is more than or equal to 99.999%), the IMS detector temperature is 40 ℃, the drift gas flow rate (E1) is 150mL/min, and the gas phase carrier gas flow rate (E2) is as follows: 2mL/min is maintained for 2min, and is increased to 10mL/min within 8min and to 150mL/min within 10 min.

2. Constructing a characteristic spectrum of the dried onion product to be identified:

by using Flavour

And detecting volatile organic compounds in the dried onion products to be identified by the gas-phase ion mobility spectrometry instrument to obtain the gas-phase ion mobility spectrometry of the dried onion products to be identified, wherein the gas-phase ion mobility spectrometry is used as a characteristic spectrum of the dried onion products to be identified, and the detection conditions of the gas-phase ion mobility spectrometry instrument are consistent with the detection conditions of the standard.

3. And (3) identifying the drying mode of the dried onion product to be identified:

and comparing the characteristic spectrum of the dried onion product to be identified with the standard characteristic spectrum, and judging that the dried onion product to be identified is the same as the standard product in the same drying mode if the matching degree of the characteristic spectrum of the dried onion product to be identified and the standard product in which the type of standard product in the standard characteristic spectrum is more than 80% in the analysis area.

4. Principal component analysis and detection result analysis

(1) Principal component analysis

By using Flavour

Dynamic principal component analysis was performed on a Dynamic PCA plug-in of a gas phase ion mobility spectrometer, and the results of clustering onion fresh samples, hot air dried standards, solar dried standards, and vacuum freeze dried standards are shown in FIG. 6.

The contribution rate of the main component PC1 of the onion is 63 percent, the contribution rate of the PC2 of the onion is 26 percent, the cumulative contribution rate of the 2 main components is up to 89 percent, and the difference of the types of the volatile organic compounds of the onion treated by different drying modes is obvious (P < 0.05). The distances between the dried onion products dried by hot air drying and solar drying are similar, which shows that the flavor substance difference of the sample after hot air drying and solar drying is smaller, and shows that the two drying modes have basically consistent effects. In addition, hot air drying can be distinguished from solar drying of dried onion products and fresh-like, vacuum freeze-dried onion products. The method provided by the invention can be used for identifying the drying mode of the dried onion product.

(2) Analysis of detection results

a. Standard feature profile analysis

As shown in fig. 5, qualitative analysis is performed on volatile components based on gas chromatography retention time and ion migration time of volatile substances, and it is found that 108 volatile substances are generated from dried onion products, and comparison is performed according to an existing database, 29 known components and 79 unknown components are determined, wherein the qualitatively detected volatile substances, which constitute the flavor substances of dried onion products, are mainly 12 aldehydes (41.38%), 8 esters (27.59%), 5 alcohols (17.24%), 3 ketones (10.34%), 3 heterocycles (11.54%), and the content of aldehyde substances is relatively highest. As can be seen from fig. 5, most of the flavor substances contained in the fresh onion are obviously reduced or disappeared after being dried, and the main substances comprise characteristic volatile organic compounds such as 2-n-pentylfuran, trans-2-heptenal, hexanal and the like, and the concentration of the volatile organic compounds is obviously higher than that of the sample in other states; after the onion is treated by different drying modes, the types of volatile organic matters are obviously increased, and new volatile organic matters appear. For example, the characteristic volatile organic compounds of the onions during hot air drying and solar energy drying mainly comprise ethyl acetate, 2-butanone, gamma-butyrolactone, nonanal, valeraldehyde, ethyl hexanoate and the like, and the characteristic volatile organic compounds of the onions during vacuum freeze drying mainly comprise ethanol, isovaleraldehyde, phenylacetaldehyde and the like, and the concentration of the organic compounds is obviously higher than that of the samples in other states.

The types of volatile organic compounds measured in FIG. 5 are explained as follows: the volatile organic compounds are numbered from left to right and are numbers 1-108 in sequence, and compared according to the existing database, 29 known components are: no. 25 is 2-n-pentylfuran, No. 27 is trans-2-heptenal monomer, No. 28 is trans-2-heptenal dimer, No. 38 is hexanal dimer, No. 39 is hexanal monomer, No. 41 is acetone, No. 42 is ethanol, No. 43 is isovaleraldehyde, No. 46 is 3-hydroxy-2-butanone, No. 57 is phenylacetaldehyde, No. 72 is ethyl acetate monomer, No. 73 is ethyl acetate dimer, No. 78 is 2-butanone dimer, No. 81 is γ -butyrolactone dimer, No. 82 is γ -butyrolactone monomer, No. 83 is nonanal monomer, No. 84 is nonanal dimer, No. 87 is pentanal monomer, No. 88 is pentanal dimer, No. 90 is n-hexanol dimer 1, No. 91 is n-hexanol monomer, No. 92 is heptanal monomer, No. 93 is heptanal dimer, No. 94 is n-pentanol monomer, No. 95 is n-pentanol monomer, no. 96 is an ethyl hexanoate monomer, No. 97 is an ethyl hexanoate dimer, No. 105 is an ethyl hexanoate monomer, No. 106 is an ethyl hexanoate dimer, and the rest numbers are 79 unknown components.

b. Analysis of discrimination results

The characteristic spectrum of the dried onion product to be identified is compared with the standard characteristic spectrum, the matching degree of the characteristic spectrum of the dried onion product to be identified and the spectrum of the hot air drying standard product in the standard characteristic spectrum in an analysis area is the highest and reaches more than 80 percent, so that the dried onion product to be identified is judged to be obtained in a hot air drying mode based on the method provided by the embodiment and is consistent with the product information when the sample is purchased, and the method provided by the embodiment can be used for identifying the drying mode of the dried onion product and has reliable identification results.

Example 4

The embodiment provides an identification method of a drying mode of dried cherry tomato products, which comprises the following steps:

1. constructing a standard characteristic map:

(1) preparation of dried cherry tomato product standard product

a. Cleaning and cutting: fresh cherry tomato is removed of base, washed, cut into halves twice, and pricked to form small holes on the surface.

b. Color protection and hot ironing: soaking the segmented cherry tomatoes in sodium bicarbonate color protection solution with the concentration of 4 per mill and the pH value of 7 to blanching with boiling water for 30 s.

c. Cooling and draining: and (4) rapidly cooling the blanched cherry tomatoes, and draining off surface water.

d. And (3) drying: uniformly spreading the drained cherry tomatoes into a single layer, respectively carrying out hot air drying, solar energy drying and vacuum freeze drying to obtain a hot air drying standard product, a solar energy drying standard product and a vacuum freeze drying standard product, wherein,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 50 ℃, and the air speed is 1 m/s;

in the drying step of the solar drying standard product, continuous day and night drying is carried out in a solar drying workshop, the temperature is 20-50 ℃, and the wind speed is 2 m/s;

in the drying step of vacuum freeze drying of the standard product, a vacuum freeze dryer is used for drying, the temperature of a cold trap is-61.4 to-62.7 ℃, and the vacuum degree is 1.0 Pa;

in the drying process of hot air drying standard products, solar drying standard products and vacuum freeze drying standard products, the moisture content is measured every half hour, and the cherry tomatoes are dried until the moisture content is lower than 8% (the mass change is not more than 1g every half hour).

e. And (3) sterilizing and packaging: and sterilizing and packaging the dried cherry tomato products to obtain a hot air drying standard product, a solar drying standard product and a vacuum freeze drying standard product respectively.

(2) Gas phase ion mobility spectrometry detection

By using Flavour

The gas-phase ion mobility spectrometry instrument is used for detecting volatile organic compounds in each standard, fresh cherry tomato samples are used as a reference, 3 samples are parallel to obtain gas-phase ion mobility spectrometry of the standard, and the gas-phase ion mobility spectrometry is used as a standard characteristic spectrum of the dried cherry tomato product standard, as shown in fig. 7, wherein the fresh cherry tomato samples are respectively marked as S1-1, S1-2 and S1-3, the hot air drying standard is respectively marked as S2-1, S2-2 and S2-3, the solar drying standard is respectively marked as S3-1, S3-2 and S3-3, and the vacuum freeze drying standard is respectively marked as S4-1, S4-2 and S4-3.

the headspace sample injection volume is 550 mu L, the incubation time is 15min, the incubation temperature is 45 ℃, the sample injection needle temperature is 85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 25min, and the column temperature is 55 ℃; the carrier gas/drift gas is high-purity nitrogen (purity is more than or equal to 99.999%), the IMS detector temperature is 45 ℃, the drift gas flow rate (E1) is 150mL/min, and the gas phase carrier gas flow rate (E2) is as follows: 2mL/min is maintained for 2min, increased to 10mL/min within 8min, and increased to 100mL/min within 10 min.

2. Constructing a characteristic spectrum of the dried cherry tomato product to be identified:

by using Flavour

Detecting volatile organic compounds in the cherry tomato products to be identified by a gas-phase ion mobility spectrometry instrument to obtain a gas-phase ion mobility spectrometry of the cherry tomato products to be identified, wherein the gas-phase ion mobility spectrometry is used as a characteristic spectrum of the cherry tomato products to be identified, and the detection conditions of the gas-phase ion mobility spectrometry instrument are consistent with the detection conditions of the standard.

3. And (3) identifying the drying mode of the dried cherry tomato product to be identified:

and comparing the characteristic spectrum of the dried cherry tomato product to be identified with the standard characteristic spectrum, and judging that the drying mode of the dried cherry tomato product to be identified and the standard product of the type are the same if the matching degree of the characteristic spectrum of the dried cherry tomato product to be identified and the standard product of the type in the standard characteristic spectrum in the analysis area is more than 80%.

4. Principal component analysis and detection result analysis

(1) Principal component analysis

By using Flavour

Dynamic principal component analysis is carried out on the Dynamic PCA plug-in of the gas phase ion mobility spectrometry instrument, and fresh cherry tomato samples, hot air drying standard products, solar drying standard products and vacuum freeze drying standard products are clustered, and the result is shown in figure 8.

The contribution rate of the main component PC1 of the cherry tomatoes is 73 percent, the contribution rate of the main component PC2 is 22 percent, the cumulative contribution rate of the 2 main components is as high as 95 percent, and the species difference of volatile organic compounds after the cherry tomatoes are treated by different drying modes is obvious (P < 0.05). The distances between the dried cherry tomato products dried by hot air and the dried cherry tomato products dried by solar energy are close, which shows that the flavor substance difference of the samples after the hot air drying and the solar energy drying is small, and shows that the effects of the two drying modes are basically consistent. In addition, hot air drying can be distinguished from solar drying and fresh-like, vacuum freeze-dried cherry tomato products. The method provided by the invention can be used for identifying the drying mode of the dried cherry tomato product.

(2) Analysis of detection results

a. Standard feature profile analysis

As shown in fig. 7, qualitative analysis is performed on volatile components based on gas chromatography retention time and ion migration time of volatile substances, 96 volatile substances are generated in the dried cherry tomato product, comparison is performed according to an existing database, 33 known components and 63 unknown components are determined, wherein the volatile substances qualitatively detected comprise 16 aldehydes (48.48%), 7 ketones (21.21%), 5 esters (15.15%), 4 alcohols (12.12%) and 1 heterocycle (3.03%) which form the flavor substances of the dried cherry tomato product, and the content of the aldehyde substances is relatively highest. As can be seen from fig. 7, most of the flavors of the cherry tomatoes are obviously reduced or disappeared after being dried, and the main substances include characteristic volatile organic compounds such as methyl caproate, n-hexanol, heptanal, 1-octen-3-one, trans-2-hexen-1-ol, n-octanal, 2-n-pentylfuran, trans-2-octenal, 3-octanone, isobutyl acetate, nonanal, hexanal, and the like, and the concentration of the volatile organic compounds is obviously higher than that of the volatile organic compounds in the samples in other states; the variety of volatile organic compounds of the cherry tomatoes treated by different drying modes is obviously reduced, and new volatile organic compounds appear. For example, the characteristic volatile organic compounds of cherry tomatoes in hot air drying and solar drying are mainly 2-butanone, 2, 3-butanediol, ethyl acetate, etc., the characteristic volatile organic compounds of cherry tomatoes in vacuum freeze drying are mainly benzaldehyde, phenylacetaldehyde, 3-methyl butyraldehyde, acetone, etc., and the concentration of the volatile organic compounds is obviously higher than that of the volatile organic compounds in samples in other states

The types of volatile organic compounds measured in FIG. 7 are explained as follows: the volatile organic compounds are numbered from left to right and are numbers 1-96 in sequence, and compared according to the existing database, 33 known components are: no. 13 is methyl hexanoate, No. 18 is n-hexanol, No. 20 is heptanal dimer, No. 21 is heptanal monomer, No. 25 is 1-octen-3-one monomer, No. 26 is 1-octen-3-one dimer, No. 28 is trans-2-heptenal monomer, No. 29 is trans-2-heptenal dimer, No. 31 is n-octanal dimer, No. 32 is n-octanal monomer, No. 34 is 2-n-pentylfuran, No. 37 is trans-2-octanal monomer, No. 38 is trans-2-octanal dimer, No. 39 is 3-octanone monomer, No. 40 is 3-octanal dimer, No. 41 is isobutyl acetate dimer, No. 42 is isobutyl acetate monomer, No. 43 is nonanal, No. 44 is methyl benzoate, No. 45 is trans-2-hexen-1-ol dimer, no. 46 is trans-2-hexen-1-ol monomer, No. 47 is hexanal dimer, No. 48 is hexanal monomer, No. 49 is benzaldehyde monomer, No. 50 is benzaldehyde dimer, No. 51 is phenylacetaldehyde, No. 57 is 3-methylbutyraldehyde, No. 60 is acetone, No. 62 is ethanol, No. 65 is 2-butanone, No. 66 is ethyl acetate, No. 68 is 3-hydroxy-2-butanone, No. 73 is 2, 3-butanediol, and the rest numbers are 63 unknown components.

b. Analysis of discrimination results

The method comprises the steps of comparing the characteristic spectrum of the dried cherry tomato product to be identified with a standard characteristic spectrum, wherein the matching degree of the characteristic spectrum of the dried cherry tomato product to be identified and the spectrum of a vacuum freeze-drying standard product in the standard characteristic spectrum in an analysis area is the highest and reaches more than 80%, so that the dried cherry tomato product to be identified is judged to be obtained in a vacuum freeze-drying mode based on the method provided by the embodiment and is consistent with product information obtained when a sample is purchased, and the method provided by the embodiment can be used for identifying the drying mode of the dried cherry tomato product and is reliable in identification result.

Example 5

The embodiment provides an identification method of a dried pleurotus eryngii product drying mode, which comprises the following steps:

1. constructing a standard characteristic map:

(1) preparation of dried pleurotus eryngii product standard substance

a. Cleaning and cutting: removing pileus from fresh Pleurotus eryngii, cleaning, and cutting into blocks of 30mm × 30 mm.

b. Color protection and hot ironing: and soaking the cut pleurotus eryngii into sodium bicarbonate color protection liquid with the concentration of 4 per mill and the pH value of 8 to blanching with boiling water for 40 s.

c. Cooling and draining: and (4) rapidly cooling the hot pleurotus eryngii, and draining the surface water.

d. And (3) drying: uniformly spreading the drained pleurotus eryngii into a single layer, and respectively carrying out hot air drying, solar energy drying and vacuum freeze drying to obtain a hot air drying standard product, a solar energy drying standard product and a vacuum freeze drying standard product, wherein,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 45 ℃, and the air speed is 1 m/s;

in the drying step of vacuum freeze drying of the standard product, a vacuum freeze dryer is used for drying, the temperature of a cold trap is-61.0 to-62.5 ℃, and the vacuum degree is 1.0 Pa;

in the drying process of hot air drying standard products, solar drying standard products and vacuum freeze drying standard products, the moisture content is measured every half hour, and the pleurotus eryngii is dried until the moisture content is lower than 8% (the mass change is not more than 1g every half hour).

e. And (3) sterilizing and packaging: and sterilizing and packaging the dried pleurotus eryngii product to obtain a hot air drying standard product, a solar drying standard product and a vacuum freeze drying standard product respectively.

(2) Gas phase ion mobility spectrometry detection

By using Flavour

The gas phase ion mobility spectrometry instrument is used for detecting volatile organic compounds in each standard, fresh pleurotus eryngii samples are used as a reference, 3 samples are parallel to obtain gas phase ion mobility spectrometry of the standard, the gas phase ion mobility spectrometry is used as a standard characteristic map of dried pleurotus eryngii product standards, as shown in fig. 9, wherein the fresh pleurotus eryngii samples are respectively marked as X1-1, X1-2 and X1-3, the hot air drying standard is respectively marked as X2-1, X2-2 and X2-3, the solar drying standard is respectively marked as X3-1, X3-2 and X3-3, and the vacuum freeze drying standard is respectively marked as X4-1, X4-2 and X4-3.

the headspace sample injection volume is 450 mu L, the incubation time is 20min, the incubation temperature is 40 ℃, the sample injection needle temperature is 85 ℃, and the incubation rotation speed is 500 r/min; the chromatographic column is FS-SE-54-CB-1, the length is 15m, and the diameter is 0.53 mm; the analysis time is 25min, and the column temperature is 60 ℃; the carrier gas/drift gas is high-purity nitrogen (purity is more than or equal to 99.999%), the IMS detector temperature is 40 ℃, the drift gas flow rate (E1) is 150mL/min, and the gas phase carrier gas flow rate (E2) is as follows: 2mL/min is maintained for 2min, increased to 10mL/min within 8min, and increased to 120mL/min within 10 min.

2. Constructing a characteristic spectrum of the dried pleurotus eryngii product to be identified:

by using Flavour

Detecting volatile organic compounds in the dried pleurotus eryngii product to be identified by a gas phase ion mobility spectrometry combined instrument to obtain gas phase ions of the dried pleurotus eryngii product to be identifiedAnd the sub-mobility spectrometry is used as a characteristic spectrum of the dried pleurotus eryngii product to be identified, and the detection condition of the gas phase ion mobility spectrometry is consistent with that of the standard substance.

3. And (3) identifying the drying mode of the dried pleurotus eryngii product to be identified:

and comparing the characteristic spectrum of the dried pleurotus eryngii product to be identified with the standard characteristic spectrum, and judging that the dried pleurotus eryngii product to be identified is the same as the standard product in the drying mode if the matching degree of the characteristic spectrum of the dried pleurotus eryngii product to be identified and the standard product in which the standard product is in the analysis area is more than 80%.

4. Principal component analysis and detection result analysis

(1) Principal component analysis

By using Flavour

Dynamic principal component analysis is carried out on a Dynamic PCA plug-in of a gas phase ion mobility spectrometry instrument, and a fresh pleurotus eryngii sample, a hot air drying standard substance, a solar drying standard substance and a vacuum freeze drying standard substance are clustered, and the result is shown in figure 10.

The contribution rate of the main component PC1 of the pleurotus eryngii is 60 percent, the contribution rate of the main component PC2 is 26 percent, the cumulative contribution rate of the 2 main components is up to 86 percent, and the difference of the types of volatile organic compounds of the pleurotus eryngii after being treated by different drying modes is obvious (P < 0.05). The distances between the dried pleurotus eryngii products dried by hot air and the dried pleurotus eryngii products dried by solar energy are close, the difference between the flavor substances of the samples dried by hot air and the flavor substances of the samples dried by solar energy is small, and the two drying modes have basically consistent effects. In addition, the dried pleurotus eryngii products dried by hot air drying and solar drying can be obviously distinguished from fresh-like and vacuum freeze-dried pleurotus eryngii products. The method provided by the invention can be used for identifying the drying mode of the dried pleurotus eryngii product.

(2) Analysis of detection results

a. Standard feature profile analysis

As shown in fig. 9, qualitative analysis is performed on volatile components based on gas chromatography retention time and ion migration time of volatile substances, it is found that 96 volatile substances are generated in a dried pleurotus eryngii product, comparison is performed according to an existing database, 48 known components and 48 unknown components are determined, wherein the qualitatively detected volatile substances form the dried pleurotus eryngii product, and the flavor substances mainly comprise 16 esters (accounting for 33.33%), 11 alcohols (accounting for 22.92%), 10 ketones (accounting for 20.83%), 6 aldehydes (accounting for 12.50%), 4 terpenes (accounting for 8.33%), and 1 heterocycle (accounting for 2.08%), and the content of the esters is relatively highest. As can be seen from fig. 9, most of the flavor substances contained in fresh pleurotus eryngii are significantly reduced or disappeared after being dried, the main substances include characteristic volatile organic compounds such as 3-pentanone, ethyl butyrate, 2-heptanone, ocimene, 2-hexenol, ethanol, ethyl acetate, acetone, leaf alcohol and the like, and the concentration of the characteristic volatile organic compounds is significantly higher than that of the characteristic volatile organic compounds in other states; after the pleurotus eryngii is treated by different drying modes, the types of volatile organic matters are obviously increased, and new volatile organic matters appear. For example, the characteristic volatile organic compounds of the pleurotus eryngii during hot air drying and solar energy drying mainly comprise gamma-butyrolactone, 3-octanone, butyl acetate, n-amyl alcohol, isoamyl acetate, valeraldehyde, 3-hydroxy-2-butanone and the like, and the characteristic volatile organic compounds of the pleurotus eryngii during vacuum freeze drying mainly comprise ethyl hexanoate, ethyl valerate, isobutyl acetate and the like, and the concentration of the organic compounds is obviously higher than that of the samples in other states.

The types of volatile organic compounds measured in FIG. 9 are explained as follows: the volatile organic compounds are numbered from left to right in turn from No. 1 to No. 96, and compared according to the existing database, the volatile organic compounds comprise 48 known components: no. 2 is a 3-pentanone monomer, No. 3 is a 3-pentanone dimer, No. 7 is ethyl butyrate, No. 10 is 2-hexenol, No. 11 is a ocimene monomer, No. 12 is an ocimene dimer, No. 13 is an ocimene polymer, No. 18 is a 2-heptanone monomer, No. 19 is a 2-heptanone dimer, No. 20 is an ethanol monomer, No. 21 is an ethanol dimer, No. 22 is an ethyl acetate monomer, No. 23 is an ethyl acetate dimer, No. 24 is acetone, No. 27 is a γ -butyrolactone dimer, No. 28 is a γ -butyrolactone monomer, No. 29 is a 3-octanone monomer, No. 30 is a 3-octanone dimer, No. 32 is furfural, No. 34 is a butyl acetate monomer, No. 35 is a butyl acetate dimer, No. 44 is an n-pentanol dimer, No. 45 is an n-pentanol monomer, No. 46 is an isoamyl acetate dimer, No. 47 is an isoamyl acetate monomer, no. 48 is a pentanal dimer, No. 49 is a pentanal monomer, No. 52 is a 3-hydroxy-2-butanone monomer, No. 53 is a 3-hydroxy-2-butanone dimer, No. 54 is a benzaldehyde monomer, No. 55 is a benzaldehyde dimer, No. 56 is an ethyl isobutyrate monomer, No. 57 is an ethyl isobutyrate dimer, No. 58 is a 1-octen-3-ol monomer, No. 59 is a 1-octen-3-ol dimer, No. 62 is a folyl monomer, No. 63 is a folyl dimer, No. 64 is a folyl dimer, No. 65 is a 2-hexenol, No. 66 is an n-butanol, No. 71 is a hexanal monomer, No. 72 is a hexanal-yielding dimer, No. 75 is a 2-n-pentylfuran, No. 86 is an ethyl hexanoate monomer, No. 87 is an ethyl hexanoate dimer, No. 89 is an ethyl valerate monomer, No. 90 is an ethyl valerate dimer, number 92 is isobutyl acetate and the remaining numbers are 48 unknown components.

b. Analysis of discrimination results

The characteristic spectrum of the dried pleurotus eryngii product to be identified is compared with the standard characteristic spectrum, the matching degree of the characteristic spectrum of the dried pleurotus eryngii product to be identified and the spectrum of the hot air drying standard product in the standard characteristic spectrum is highest in an analysis area and reaches more than 80%, therefore, the dried pleurotus eryngii product to be identified is judged to be obtained in a hot air drying mode based on the method provided by the embodiment and is consistent with the product information when the sample is purchased, and the method provided by the embodiment is proved to be used for identifying the drying mode of the dried pleurotus eryngii product and the identification result is reliable.

The result of the principal component analysis in the embodiments 1 to 5 and the result of the verification of the sample with the known drying mode can be obtained, and the identification method provided by the invention can be used for identifying the drying mode of the dried vegetable product, is simple to operate, does not need pretreatment, and has reliable identification result. And repeated experiments verify that the method is suitable for identifying most dried vegetable products in a common drying mode and has universality.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The method for identifying the drying mode of the dried vegetable product is characterized by comprising the following steps of:

2. The method for identifying a drying pattern of a dried vegetable product as set forth in claim 1, wherein the dried vegetable product standard comprises: hot air drying standard, solar drying standard and vacuum freeze drying standard.

3. The method for identifying the drying mode of dried vegetable products as set forth in claim 2,

in the step of drying the standard product by hot air, the temperature of a hot air drying oven is 40-50 ℃, and the air speed is 1-1.5 m/s;

4. The method for identifying the drying mode of dried vegetable products as set forth in claim 2,

in the drying steps of the hot air drying standard product, the solar drying standard product and the vacuum freeze drying standard product, the vegetables are dried until the moisture content of the vegetables is lower than 6-8%, or the mass change of the vegetables is not more than 1g every half hour.

5. The method for identifying a dried vegetable product drying method as claimed in claim 1, wherein the gas phase ion mobility spectrometry is performed under the following conditions:

6. The method for identifying a dried vegetable product drying method as claimed in claim 5, wherein the gas phase ion mobility spectrometry is performed under the following conditions:

7. The method for identifying the drying mode of dried vegetable products as claimed in claim 1, wherein the preparation method of each type of dried vegetable product standard in step (1) comprises: the vegetable is sequentially washed and cut, color-protected hot-ironed, cooled and drained and dried.

8. The method for identifying the drying mode of the dried vegetable product as claimed in claim 7, wherein the color protection blanching is to immerse the cleaned and cut vegetables into a sodium bicarbonate color protection solution for boiling water blanching, wherein the concentration of the sodium bicarbonate color protection solution is 1-5 per mill, the pH value is 5-9, and the time for blanching in boiling water is 30-60 s.

9. The method for identifying the drying mode of the dried vegetable product as claimed in claim 8, wherein the concentration of the sodium bicarbonate color protection solution is 2-4 ‰, the pH value is 6-8, and the blanching time in boiling water is 30-45 s.

10. The method for identifying the drying mode of the dried vegetable product according to any one of claims 1 to 9, wherein the dried vegetable product is a dried product of spinach, cabbage, onion, cherry tomato or pleurotus eryngii.