CN109142655B

CN109142655B - Method for identifying inferior edible oil

Info

Publication number: CN109142655B
Application number: CN201810971227.9A
Authority: CN
Inventors: 徐恩良
Original assignee: Xiamen Guangmian Bio Tech Co ltd
Current assignee: Xiamen Guangmian Bio Tech Co ltd
Priority date: 2018-08-24
Filing date: 2018-08-24
Publication date: 2021-01-12
Anticipated expiration: 2038-08-24
Also published as: CN109142655A

Abstract

The invention relates to the field of edible vegetable oil and oil identification, and discloses an identification method of inferior edible oil and fat, which comprises the following steps: (1) establishing a standard map: placing the refined qualified vegetable oil and the water solution into a plastic pipe according to the volume ratio of (0.5-2) to 1, tightly covering, reversing and uniformly mixing, and then standing and layering to obtain a standard map, wherein the standard map respectively comprises an upper grease layer, an upper grease interface, a water phase, a lower grease layer and vacuoles from top to bottom; (2) establishing a to-be-detected map: placing the grease to be detected and the aqueous solution into a plastic tube according to the volume ratio of (0.5-2) to 1, tightly covering, reversing and uniformly mixing, and then standing and layering to obtain a spectrum to be detected; (3) and (3) identification: and comparing the to-be-detected map with the standard map. When the grease to be detected is inferior oil, corresponding characteristic changes can be seen at the upper grease layer, the upper oil-water interface, the water phase, the lower grease layer and the vacuole, an abnormal map is formed, the map can be seen by naked eyes, and the oil product can be identified quickly and conveniently.

Description

Method for identifying inferior edible oil

Technical Field

The invention belongs to the field of edible vegetable oil and oil identification, and particularly relates to an identification method of inferior edible oil and fat.

Background

The oil is an essential nutrient substance in the life process of a human body, and has the basic functions of forming cells and organelles, storing and generating energy, forming connective tissues to maintain physiological structures and functions, synthesizing bioactive substances and providing a necessary fat-soluble environment for the bioactive substances such as fat-soluble vitamins and the like. Among them, fats and phospholipids are most important. Some of the essential fatty acids constituting fats and oils (linoleic acid of n-6 series and linolenic acid of n-3 series are two kinds of fatty acids essential to the human body) cannot be synthesized by the human body itself and must be obtained from food. Since vegetable oils are the main source of essential fatty acids, the consumption of acceptable vegetable oils that meet the physiological needs of the human body is particularly important to humans.

The commercial edible vegetable oil in China is subject to non-standard use of the manufacturing process, non-strict standard execution, wide and uneven temperature control, and random blending of different oil varieties, so that the quality of the edible oil made from normal oil plants is not uniform, and certain adverse effects are generated on normal physiological needs of human groups. Moreover, driven by commercial interest, some poor-quality oils from non-edible sources, namely "ground purchased oil", enter the circulation of edible oil production. This is against ethics, and introduces a large amount of harmful non-healthy components into human body, and causes essential fatty acid and other deletions, which brings serious health hazard to human population.

When the household and the catering industry in China cook food, because the harm caused by high temperature and overheating of the grease is not known enough, the manufacturing methods of frying, frying and frying the grease at high temperature and even over fire are all good, and the frying oil is used repeatedly. On one hand, unsaturated fatty acids including essential fatty acids are destroyed to lose nutritional value, and after long-term eating, the health is seriously harmed; on the other hand, a plurality of harmful substances including acrolein, benzopyrene and the like are generated, and the health of housewives and chefs is harmed.

Heretofore, the problems of these harmful oils and fats in the market of commercial edible vegetable oils have not been completely eradicated and have been on a long-term basis. The related detection technical scheme is not approved by most, the problems still exist, and the long-term harm is caused to the society.

CN110554106A discloses a vegetable oil adulteration identification method, which comprises the steps of dissolving a vegetable oil sample in an organic solvent, taking n-octane-isopropanol or n-heptane-isopropanol as a mobile phase, taking a porous graphite carbon column as a stationary phase, and carrying out separation analysis by adopting a high performance liquid chromatography-mass spectrometer to determine whether 2-palmitoyl-1, 3-stearoyl oleyl glyceride is contained.

CN111398238A discloses a laser-induced fluorescence spectrum recognition method of edible oil doped with castor oil, which comprises the following steps: s1, collecting original fluorescence spectrum data of oil samples of the edible oil doped with castor oil in different proportions by using an edible oil fluorescence spectrum analyzer; s2, filtering the spectral curve by a polynomial smoothing method to eliminate noise; s3, performing characteristic wavelength screening on the spectral data of the oil sample by using a continuous projection algorithm, and selecting wavelength points in the original fluorescence spectral data; s4, randomly generating a training set and a testing set according to the ratio of 4:1 of the screened spectrum data; s5, enabling training set data to construct a data model, optimizing regularization parameters and kernel function width coefficients of the data model by adopting a CSA algorithm in the training process, testing the classification performance of the optimized data model through a test set, finally outputting the classification accuracy of the data model, and verifying the identification effect of the established model.

CN111413320A discloses an olive oil adulteration detection method based on Raman spectrum, which comprises the following steps: s1, selecting a plurality of oil samples of different types, such as rapeseed oil, soybean oil, palm oil and frying oil, respectively mixing the oil samples with olive oil in different proportions, preparing at least 10 sets of samples according to different mixing proportions for each oil sample, collecting at least 10 sets of Raman spectrum data for each set of sample, and storing all the oil samples in a dark environment at room temperature until the measurement is carried out in order to keep consistent test conditions; and S2, exciting the Raman spectrum of the oil sample to be detected by using incident laser, collecting signals through optical fiber transmission and an optical fiber probe, transmitting the collected signals into a Raman spectrometer for light splitting and analog-to-digital conversion, and finally comparing and analyzing the characteristic peak of the Raman spectrum consisting of molecules in the oil sample to be detected and the sample in S1 by using a computer to obtain a detection result.

However, the above identification methods can be realized only by means of instruments such as a high performance liquid chromatography-mass spectrometer, a fluorescence spectrometer and a raman spectrometer, and are not suitable for on-site rapid law enforcement detection.

Disclosure of Invention

The invention aims to provide an identification method for simply and conveniently providing inferior edible vegetable oil for families, oil processing enterprises or government regulatory agencies, and whether the edible vegetable oil is the inferior oil can be identified by adopting the method.

After intensive research, the inventor of the invention discovers that when vegetable oil and aqueous solution are mixed in a plastic pipe (the pipe inner diameter phi is 8-12mm, the height is 40-60mm, the lower part is 1/3 is conical) with a specific size according to the volume ratio of (0.5-2) to 1, the vegetable oil, the aqueous solution and the plastic structure interface form a characteristic macroscopic polymorphic map, the polymorphic map is mainly based on the phenomena of oil fatty acid composition, rancidity products, polar components, transparency (oil phase, water phase and oil-water boundary), impurities and non-oil components such as hydrophobicity, dissolution, precipitation, turbidity, adhesion and the like in the oil phase, the water phase, the oil-water interface and the plastic interface, and the polymorphic map is directly embodied by the oil components and is directly related to the oil quality, so that the vegetable oil is identified. Based on this, the present invention has been completed.

Specifically, the method for identifying the inferior edible oil provided by the invention comprises the following steps:

(1) establishing a standard map: placing the refined qualified vegetable oil and the water solution into a plastic pipe according to the volume ratio of (0.5-2) to 1, covering the plastic pipe tightly, turning upside down and mixing uniformly, and then standing and layering to obtain a standard map, wherein the standard map comprises an upper grease layer, an upper grease interface, a water phase, a lower grease layer and vacuoles from top to bottom;

the upper oiling interface is an upper arched arc interface formed between the upper oiling layer and the water phase;

the lower grease layer is of a grease layer structure which cannot go upwards to the top end completely;

the vacuole is air remained when the bottom grease floats upwards;

(2) establishing a to-be-detected map: placing the grease to be detected and the aqueous solution into a plastic pipe according to the volume ratio of (0.5-2) to 1, tightly covering the plastic pipe, turning upside down and uniformly mixing, and then standing and layering to obtain a spectrum to be detected;

the sizes of the plastic pipes adopted when the standard map and the map to be detected are respectively and independently 8-12mm of pipe inner diameter phi, 40-60mm of height and 1/3 below are conical;

standing and layering time for establishing standard map and to-be-detected map is preferably 5-20min independently;

(3) and (3) identification: and comparing the to-be-detected map with the standard map, and when the to-be-detected map is more than any one of the following conditions, indicating that the to-be-detected grease is inferior oil:

the oil layer is turbid and/or any one of aggregates, bubbles and oily impurities appears;

the interface of the oil and water is not clear and/or bubbles and/or burrs occur;

③ the water phase is in an opacification state and/or contains impurities;

(iv) at least one of the lower grease layer and the vacuoles disappears.

The identification method of the inferior edible oil provided by the invention has the following outstanding advantages and beneficial effects:

1. when the oil to be detected is impure, corresponding characteristic changes can be seen at the upper oil layer, the upper oil-water interface, the water phase, the lower oil layer and the vacuole, so that an abnormal map is formed and can be identified.

2. The method is rapid and convenient, visible to the naked eye, simple and intuitive, and is very suitable for field inspection and analysis.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a standard spectrum formed by refined rapeseed oil;

FIG. 2 is a standard spectrum formed from refined soybean oil;

FIG. 3 is a standard spectrum formed from refined peanut oil;

FIG. 4 is a standard spectrum formed by refined tea oil;

FIG. 5 is a standard spectrum formed from refined corn oil;

FIG. 6 is a standard spectrum formed by refining sunflower oil;

FIG. 7 is a standard spectrum formed from refined palm oil;

FIG. 8 is a spectrum of deep-frying oil mixed with animal or vegetable fat in example 2.

Description of the reference numerals

1-plastic pipe cover, 2-plastic pipe body, 3-molecular wetting interface, 4-grease upper interface, 5-upper grease layer, 6-upper grease interface, 7-included angle, 8-water phase, 9-lower grease layer upper interface, 10-lower grease layer, 11-vacuole, 12-oily impurity, 13-water-soluble impurity.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.

As shown in FIG. 1, the materials used in the present invention include refined vegetable oils, aqueous solutions and plastic pipes. Wherein, the plastic pipe comprises a plastic pipe cover 1 and a plastic pipe body 2 which are tightly matched. The formed map comprises an upper grease layer 5, an upper water interface 6, a water phase 8 and a lower grease layer 10, and a detailed structure of the map is formed due to the characteristic reaction of grease components, aqueous solution and the plastic pipe in each structural layer. The fine structure comprises a molecule wetting interface 3, an oil upper interface 4, an upper oil layer 5, an upper oil-water interface 6, an included angle 7, a water phase 8, a lower oil layer upper interface 9, a lower oil layer 10, vacuoles 11, oily impurities 12 and water-soluble impurities 13, and the fine structure can also have meat-visible changes according to different oil qualities, so that the oil components and the oil qualities are displayed.

The molecule infiltration interface 3 is an upward extending interface formed by upward infiltration of grease molecules and plastics by virtue of hydrophobic force.

The grease upper interface 4 is an upper liquid level of grease spread out in the plastic pipe under the action of gravity, and is upwards infiltrated under the action of hydrophobic property to form an arc interface with a low bottom.

The upper grease layer 5 is a grease layer to be analyzed, and is constantly positioned on the upper layer of the water phase 8 because the specific gravity of grease is smaller than that of the water solution. Normally, the oil is displayed as the natural color of the oil, is clear and transparent, and has no visible impurities. Inferior oil exhibits characteristic oil changes, such as clarity, condensate, bubbles, oily impurities, and the like, under the action of polar components, transparency (oil phase, water phase, and oil-water boundary), impurities, and non-oil components.

The upper oil-water interface 6 is an upper arched arc interface formed between the grease and the water solution. The normal grease is a clear and bright thin layer, the boundary limit between the normal grease and the water solution of the upper grease is clearly visible, and the vegetable oil except the palm oil is in an upward cap-shaped structure. If bubbles and burrs appear on the upper oil-water interface 6, the phenomenon of overheating polarization of the grease is indicated.

As mentioned above, the upper oil-water interface 6 is an upper arched arc interface formed between the upper grease layer 5 and the water phase 8, and forms an included angle 7 between the upper arched arc interface and the plastic pipe body 2, in which grease is infiltrated downwards. The arch height and the included angle on the arc-shaped interface are mainly related to the composition of fatty acid of grease, the arch curvature on the arc-shaped interface of vegetable oil with more short-chain fatty acid, such as peanut oil and palm oil, is small and flat, and the included angle is larger and is approximately vertical to the pipe wall; the curvature of the upper arched interface formed by vegetable oil with abundant long-chain fatty acid, such as rapeseed oil, soybean oil, tea oil, sunflower seed oil, etc., is large, and the included angle formed between the upper arched interface and the pipe wall is less than 90 degrees. Various vegetable oil characteristic values can be fixed through accurately calculating the size of the included angle 7 and serve as the oil characteristic parameters. The upper oil-water interface 6 is not clearly demarcated from the water-phase interface due to the water-soluble components in the oil and fat, and is regarded as a foreign image.

The water phase 8 is of an aqueous solution structure which is fully and uniformly mixed with the grease, and is clear and transparent in normal times and free of foreign matters or impurities. The water-soluble components or rancid products of the inferior fats and oils are dissolved in the aqueous solution, or are in an opaque state, or contain impurities derived from the fats and oils dissolved in the aqueous solution.

The upper interface 9 and the lower grease layer 10 of the lower grease layer are grease layer structures which can not all go up to the top end, and the formation reason is that grease molecules and plastics are larger than buoyancy formed by the difference of specific gravity of aqueous solution and grease by virtue of hydrophobic action force. Any damage to the hydrophobic nature of the grease molecules can weaken the formation of the sidewall adhesion of the lower grease layer, such as an increase in the polar material content of the grease (resulting in increased hydrophilicity). The natural vegetable oil has rich unsaturated fatty acid content, complete and long carbon chain and strong hydrophobic effect, so that the oil can deposit on the bottom of the pipe more. When polar substances in the grease are increased, the hydrophobic effect is weakened, so that the lower grease layer is reduced or eliminated. For acceptable vegetable oils, the presence of the lower grease layer upper interface 9 and lower grease layer 10 is essential.

The vacuoles 11 are air remaining when the bottom grease floats, and disappear together with the lower grease layer when the polar substances of the grease increase.

Based on this, the identification method of the inferior edible oil provided by the invention comprises the following steps:

(1) establishing a standard map: placing the qualified refined vegetable oil and the water solution into a plastic pipe according to the volume ratio of (0.5-2) to 1, covering the plastic pipe tightly, turning upside down and uniformly mixing, and then standing and layering to obtain a standard map, wherein the standard map comprises an upper grease layer 5, an upper water interface 6, a water phase 8, a lower grease layer 10 and vacuoles 11 from top to bottom;

the upper oiling interface 6 is an upper arched arc interface formed between the upper oiling layer 5 and the water phase 8;

the lower grease layer 10 is of a grease layer structure which cannot go all the way up to the top end;

the vacuole 11 is air remained when the bottom grease floats upwards;

the sizes of the plastic pipes used for establishing the standard map and the map to be detected are respectively and independently the inner diameter of the pipe

8-12mm, 40-60mm high and 1/3 conical lower part;

③ the water phase is in an opacification state and/or contains impurities;

(iv) at least one of the lower grease layer and the vacuoles disappears.

Preferably, the size, the oil-water ratio and the standing and layering time of the plastic pipe adopted when the standard map and the map to be detected are established are the same.

Preferably, the standing and layering time is 5-20 min.

Preferably, the grease spectrum to be detected is compared and compared by adopting a standard spectrum established by corresponding refined qualified vegetable oil.

Preferably, the refinery-qualified vegetable oil is selected from peanut oil, corn oil, palm oil, rapeseed oil, soybean oil, tea oil, or sunflower seed oil.

Preferably, the method for identifying the inferior edible oil further comprises the steps of respectively establishing standard maps for the peanut oil, the corn oil, the palm oil, the rapeseed oil, the soybean oil, the tea oil and the sunflower seed oil according to the method in the step (1) to obtain a standard map library, and comparing the maps to be detected with the standard maps in the standard map library one by one in the identification process in the step (3), so that not only can the quality of the oil be identified, but also the type of the oil can be further identified.

The present invention will be described in detail below by way of examples.

The dimensions of the plastic tubes used in the following examples are as follows: the tube has an inner diameter of 10mm, a height of 50mm and a conical lower part 1/3.

Example 1 establishment of Standard atlas

Adding refined vegetable oil (rapeseed oil, soybean oil, peanut oil, tea oil, corn oil, sunflower seed oil and palm oil) and aqueous solution into a plastic pipe according to a volume ratio of 1:1, wherein the plastic pipe comprises a plastic pipe cover 1 and a plastic pipe body 2 which are closely matched, tightly covering the plastic pipe cover 1, and reversing and mixing the materials at room temperature for several times to respectively obtain a standard map shown in figures 1-7, and the standard map respectively comprises a molecule infiltration interface 3, an oil upper interface 4, an upper oil layer 5, an upper oil water interface 6, a water phase 8, a lower oil layer upper interface 9, a lower oil layer 10 and a vacuole 11 from top to bottom. Wherein:

the molecule infiltration interface 3 is an upward extending interface formed by grease molecules and plastics along the pipe wall, and the bottom of the interface is clear.

The grease upper interface 4 is an arc-shaped interface liquid level with the lower bottom of the grease spread out in the plastic pipe under the action of gravity.

The upper grease layer 5 is a grease layer which is constantly positioned on the upper layer of the aqueous solution due to the specific gravity of the upper grease layer being smaller than that of the aqueous solution, and is changed by specific grease under the actions of polar components, transparency (oil phase, water phase and oil-water boundary), impurities, non-grease components and the like, and the upper grease layer 5 of the refined vegetable oil is clear, uniform, free of impurities and free of visible foreign matters.

The upper oil-water interface 6 is a clear upper arched arc interface formed between the grease and the water phase, and forms an included angle 7 between the upper arched arc interface and the plastic pipe body, wherein the grease is infiltrated downwards. As can be seen from fig. 1 to 7, the camber of the arc interface of the vegetable oil with more short-chain fatty acid, such as peanut oil (saturated fatty acid content: 21%) and palm oil (saturated fatty acid content: 35%), is small and flat, and the included angle is larger than that of the common vegetable oil; the arc interface formed by vegetable oil with abundant long-chain fatty acid, such as rapeseed oil (with saturated fatty acid content of 6%), soybean oil (with saturated fatty acid content of 15%), tea oil (with saturated fatty acid content of 11%), and corn oil (with saturated fatty acid content of 14%) and sunflower seed oil (with saturated fatty acid content of 11%) has large camber and is in cap shape, and the included angle is small. The oil-water interface of the refined vegetable oil is clear and uniform, and no impurities or foreign matters are visible.

The water phase 8 is of a water solution structure which is fully and uniformly mixed with the grease, is clear and has no impurities.

The upper interface 9 and the lower grease layer 10 of the lower grease layer are grease layer structures which cannot go up to the top completely, the interface is arc-shaped and clear, and the bottom is exposed.

The vacuole 11 is air remained when the bottom grease floats.

Example 2 (deep frying oil of animal and vegetable fat)

(1) Establishing a standard map:

standard spectra were created as in example 1.

(2) Establishing a to-be-detected map:

adding the animal and vegetable oil mixed deep-frying oil to be detected and the aqueous solution into a plastic pipe according to the volume ratio of 1:1, wherein the plastic pipe comprises a plastic pipe cover 1 and a plastic pipe body 2 which are closely matched, tightly covering the plastic pipe cover 1, and turning and uniformly mixing for several times at room temperature to obtain a map shown in figure 8, and the map comprises a molecular infiltration interface 3, an oil upper interface 4, an upper oil layer 5, an upper oil-water interface 6 and a water phase 8 from top to bottom respectively.

The molecule infiltration interface 3 is an upward extending interface formed by animal and vegetable fat mixed deep-fried fat molecules and plastics along the pipe wall, and the bottom of the interface is clearer.

The grease upper interface 4 is an arc interface upper liquid level with the lower bottom of the grease spread out in the plastic pipe under the action of gravity.

The upper oil layer 5 is a deep-fried oil layer mixed with animal and vegetable oil, is constantly positioned on the upper layer of the water phase due to the specific gravity of the deep-fried oil layer being smaller than that of the water solution, has unclear lower part, has bubbles or aggregates, is not uniform, and has visible impurities and foreign matters.

The side surface of the upper oil-water interface 6 is in a straight line, is an unclear oil-water plane interface formed between the grease and the water phase, and forms a grease which is soaked downwards and forms a right angle with the pipe wall included angle 7 with the plastic pipe wall. Because the deep-fried oil and fat mixed with animal and vegetable oil and fat contains high saturated fatty acid and more short-chain fatty acid, the arc interface has small and flat camber, and the included angle is larger than that of common vegetable oil and is close to a right angle, so the interface formed between the oil and the water phase is planar. The deep-fried oil and fat mixed by animal and vegetable oil and fat has complicated components, wide oil/water solution interface, extends to the oil/water solution, has burrs and is fuzzy.

The water phase 8 is an aqueous solution structure which is fully and uniformly mixed with the grease, and is unclear, or has small bubbles or aggregates, is not uniform, and has impurities and foreign matters visible.

The lower grease layer 10 and the vacuoles 11 described in the standard spectrum all disappeared, indicating that there were very many polar substances in the grease and oily impurities 12 and water-soluble impurities 13 appeared.

From the above results, it can be seen that the deep-frying oil containing more polar components is inferior.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A method for identifying inferior edible oil is characterized by comprising the following steps:

(1) establishing a standard map: placing the qualified refined vegetable oil and the water solution into a plastic pipe according to the volume ratio of (0.5-2) to 1, covering the plastic pipe tightly, turning upside down and uniformly mixing, and then standing and layering to obtain a standard map, wherein the standard map comprises an upper grease layer (5), an upper grease interface (6), a water phase (8), a lower grease layer (10) and vacuoles (11) from top to bottom;

the upper oiling water interface (6) is an upper arched arc interface formed between the upper oiling layer (5) and the water phase (8);

the lower grease layer (10) is of a grease layer structure which cannot go all the way up to the top end;

the vacuole (11) is air remained when the bottom grease floats upwards;

③ the water phase is in an opacification state and/or contains impurities;

(iv) at least one of the lower grease layer and the vacuoles disappears.

2. The identification method according to claim 1, wherein the standard map and the map to be detected are established by using plastic pipes having the same size, oil-water ratio and standing time for layering.

3. The method of claim 2, wherein the standing and layering time is 5 to 20 min.

4. The identification method according to any one of claims 1 to 3, wherein the oil and fat profile to be detected is compared and compared with a standard profile established by corresponding refined and qualified vegetable oil.

5. Identification method according to any one of claims 1 to 3, characterized in that the vegetable oil qualified for refining is selected from peanut oil, corn oil, palm oil, rapeseed oil, soybean oil, tea oil or sunflower oil.

6. The identification method according to any one of claims 1 to 3, further comprising establishing standard spectra for peanut oil, corn oil, palm oil, rapeseed oil, soybean oil, tea oil and sunflower seed oil according to the method of step (1) to obtain a standard spectrum library, and comparing the standard spectra with the standard spectra in the standard spectrum library one by one during the identification process of step (3) to further identify the type of the oil to be detected.