CN107367468B - Dissociate in a kind of edible oil fatty acid determination method - Google Patents
Dissociate in a kind of edible oil fatty acid determination method Download PDFInfo
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- CN107367468B CN107367468B CN201710655504.0A CN201710655504A CN107367468B CN 107367468 B CN107367468 B CN 107367468B CN 201710655504 A CN201710655504 A CN 201710655504A CN 107367468 B CN107367468 B CN 107367468B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/29—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using visual detection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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Abstract
The embodiment of the invention provides a kind of semiquantitative determination methods of free fatty acid in edible oil, the free fatty acid that include: (1) extracted with extractant in edible oil, obtain the extraction phase to be measured containing free fatty acid, wherein the volume of the extractant and the volume of edible oil are identical；(2) extraction phase to be measured of designated volume is taken, and is separately added into nano-Au solution and cationic polymer solution thereto, color is fully mixed to and no longer changes, obtain Colorimetric System to be measured；(3) color of the Colorimetric System to be measured is compared with the color of Standard Colorimetric System respectively, determines the content range of free fatty acid in edible oil.Free fatty acid determination method in edible oil provided in an embodiment of the present invention has the advantage that (1) analysis time of the invention is short, can complete semi-quantitative analysis in a few minutes, compared with titration method, detection is more rapidly.(2) present invention is few using the amount of organic solvent, environmentally protective.
Description
Technical field
The present invention relates to edible oil quality control technology fields, more particularly to a kind of survey of free fatty acid in edible oil
Determine method.
Background technique
During free fatty acid (FFA) in edible oil occurs mainly with its processing and stores.Free fatty acid occurs
It is rotten to generate the H being harmful to the human body2O2.Therefore, in edible oil the content (total content) of free fatty acid usually as assessment
One critically important parameter of edible oil quality and economic value.The standard method detected at present mainly has U.S.'s oil product Science of Chemistry
The national standard method (GB/T 5530-2005) of meeting (AOCS), the European Community (EC) and China, these methods are similar, all
Recommendation dissolves a sample in ethyl alcohol, uses highly basic as titrant, and phenolphthalein is that indicator surveys free fatty acid content
It is fixed.Titration method the disadvantages of there is only time-consuming, consumption solvents, and when oil samples color to be measured is deeper by titration method very
Hardly possible judges its titration end-point.In view of this, the free fatty acid how faster to detect in edible oil becomes this field
Technical staff's urgent problem to be solved.
Summary of the invention
Nanogold (AuNPs) refers to diameter in the molecule of the gold of 1~100nm, the study found that when nanogold partial size exists
When in the range of 10-50nm, nano-Au solution takes on a red color.And after nanogold is assembled, surface plasma body resonant vibration is inhaled
Red shift occurs for take-up, and correspondingly, nano-Au solution color experience becomes blue from red, and this variation can with the naked eye be seen
It examines.Importantly, their molar extinction coefficient is very high, three orders of magnitude higher than conventional organic coloring agent, therefore detect spirit
Sensitivity is high.
The surface of cationic polymer is general or can have positive charge under certain condition, this characteristic can cause to disperse
The nanogold of state is assembled, and the nanogold of state of aggregation is formed, to change the color of nano-Au solution, makes nano-Au solution face
Color becomes blue (state of aggregation) from red (dispersed).
The research of the invention finds that the cationic polymer of micro-molar concentration (uM) rank, the dendroid polyamides in especially whole generation
Amine amine is easy to allow nanogold that clustering phenomena occurs；Nanogold (dispersed) solution colour is red, and central absorption wavelength exists
520nm；When certain density cationic polymer, such as the dendroid daiamid (PAMAM G1.0) in 1 generation are added thereto
After macromolecular, macromolecular makes nanogold particle that clustering phenomena have occurred, and causes nano-Au solution color in a short time, such as
Become within 3-5 seconds blue, center maximum absorption wavelength is transferred to 650nm at this time.It is added when into nanogold (dispersed) solution
The fatty acid that concentration is identical but chain length is different when adding above-mentioned cationic polymer, it is found that butyric acid and caproic acid are several to assembling
There is no inhibiting effect, solution becomes blue immediately after PAMAM is added；But with the increase of carbon chain lengths, the fatty acid pair of addition
The inhibiting effect of aggregation also increases, and shows as the color of solution without becoming blue completely, also keeps a degree of red, it can
Inhibit the generation of this aggregation to some extent.Present invention research is it has furthermore been found that carbon chain lengths are the fatty acid pair of C16-C18
The aggregation rejection ability of nanogold is close；Meanwhile the fatty acid in edible oil is mainly palmitinic acid (C16-0), stearic acid (C18-
0), oleic acid (C18-1) and linoleic acid (C18-2) (GB 19111-2003；Journal of Agricultural and Food
Chemistry, 2011,59,10775-10780), in view of this, the embodiment of the invention provides the rouge that dissociates in a kind of edible oil
The measuring method of fat acid, to realize the free fatty acid that can faster detect in edible oil.Specific technical solution is as follows:
First aspect present invention provides a kind of fatty acid determination method of dissociating in edible oil comprising:
(1) with the free fatty acid in extractant extraction edible oil, the extraction phase to be measured containing free fatty acid is obtained,
In, the volume of the extractant and the volume of edible oil are identical；
(2) extraction phase to be measured for taking designated volume, it is mixed with nano-Au solution and cationic polymer solution,
No longer change to color, obtains Colorimetric System to be measured；
(3) color of the color of the Colorimetric System to be measured and Standard Colorimetric System is compared, is determined in edible oil
The content range of free fatty acid；
Wherein, the Standard Colorimetric System determines by the following method:
The standard solution of different content of fatty acid is prepared with the extractant from fatty acid standards, in the standard solution
Content of fatty acid it is known that the fatty acid standards be selected from C16-C18 fatty acid；
The standard solution for taking the designated volume respectively mixes it with nano-Au solution and cationic polymer solution
It closes, until color no longer changes, obtains Standard Colorimetric System；The volume phase of the Standard Colorimetric System and the Colorimetric System to be measured
Together；And in the Standard Colorimetric System nanogold and the concentration of cationic polymer respectively with nanometer in the Colorimetric System to be measured
Gold is identical with the concentration of cationic polymer.
In a kind of specific embodiment of first aspect present invention, in step (3), free-fat in edible oil is determined
Acid content range, specifically: when the Colorimetric System to be measured color between two adjacent content of fatty acid standard solution
When between the color of corresponding Standard Colorimetric System, determine the content of free fatty acid in edible oil in described two adjacent rouge
Between fat acid content.
In practical applications, different content of fatty acid can be prepared according to the edible oil acidity value upper limit of national Specification
Standard solution, for example, standard GB/T 19111-2003 regulation level-one, second level, three-level and level Four squeeze finished product edible corn
The acidity value (in terms of KOH, mg/g) of oil should be no more than 0.2,0.3,1.0,3.0；Content of fatty acid in corresponding standard solution
It is indicated with fatty acid molar concentration, respectively 4.46mM, 6.70mM, 22.3mM and 67.0mM.In the case, in step
It (3), can be by standard colorimetric corresponding to the color of Colorimetric System to be measured and such as level-one, second level, three-level and four grade standards in
The color of system is compared；When the color of Colorimetric System to be measured is between the color corresponding to two neighboring rank, so that it may
Content to determine the free fatty acid in edible oil may be implemented to measure containing for sxemiquantitative between the two neighboring rank
It is fixed.In the present invention, standard solution institute of the color of the described Colorimetric System to be measured between two adjacent content of fatty acid
Between the color of corresponding Standard Colorimetric System, it can be understood as the red phase (blue phase) that the Colorimetric System to be measured is presented
The red phase (blue phase) that Standard Colorimetric System corresponding to standard solution between two adjacent content of fatty acid is presented it
Between.
In a kind of specific embodiment of first aspect present invention, fatty acid standards are selected from palmitinic acid, stearic acid, oil
At least one of acid and linoleic acid.
In a kind of specific embodiment of the invention, after making Standard Colorimetric System, its color can be passed through
Optional mode is recorded on carrier, such as can recorde on card or plate, is made as with Standard Colorimetric System color
Standard color comparison card or standard colorimetric plate；The color that Standard Colorimetric System can be saved for a long time in this way, when need detect to
When surveying the color gamut of Colorimetric System, as long as by the color contrast of itself and standard color comparison card or standard colorimetric plate.It needs
Bright, described carrier, can be with other any suitable for Standard Colorimetric System face is presented other than it can be card or plate
The carrier of the material of color.
In a kind of specific embodiment of the invention, the color of the Colorimetric System to be measured and the face of Standard Colorimetric System
Color specifically can be with the absorbance peak of Colorimetric System to be measured and the respective uv-visible absorption spectra of Standard Colorimetric System come table
Show.Specifically, absorbance value A at 520nm can be passed through520It indicates, or by passing through absorbance value A at 650nm650Carry out table
Show.In this embodiment, as the A of the Colorimetric System to be measured520Standard solution institute between two adjacent content of fatty acid is right
The A for the Standard Colorimetric System answered520Between when, determine the content of free fatty acid in edible oil in described two adjacent fatty acid
Between content.Or the A when the Colorimetric System to be measured650Mark corresponding to standard solution between two adjacent content of fatty acid
The A of quasi- Colorimetric System650Between when, determine the content of free fatty acid in edible oil described two adjacent content of fatty acid it
Between.
It, can be in advance by the absorbance of Standard Colorimetric System in order to further shorten the fatty acid determination time in edible oil
Peak value, such as A520Or A650It records, it, can be in the absorbance peak for determining Colorimetric System to be measured, such as A when detection520
Or A650Afterwards, it is directly compared with the absorbance peak of the Standard Colorimetric System recorded；Easily and fast.
In the inventive solutions, extractant should select fully, by free fatty acid to extract from edible oil
It takes out, even if free fatty acid is transferred in extractant from edible oil, the extraction phase containing fatty acid is formed, in order to examine
It surveys.Based on this, in a kind of specific embodiment of first aspect present invention, extractant is the mixed solvent of methanol and water, excellent
Selection of land, the volume ratio of methanol and water is 2:1 in the extractant, i.e., the described extractant is by the methanol that volume ratio is 2:1 and water
It mixes.
In a kind of specific embodiment of first aspect present invention, the grain of nanogold contained in the nano-Au solution
Diameter range is 10-50nm；Preferably 10-20nm, more preferably 13nm.In the present invention, to the source of nanogold without limit
It is fixed, for example, reduction method for preparing nanometer gold solution can be used；During reduction method for preparing nanometer gold, gold chloride is gone back in original
Under the action of agent, it is polymerized to a certain size nanogold particle, forms the hydrophobic sol solution of electronegative nanogold, the nanogold is hydrophobic
Sol solution can be used as nano-Au solution use.Common reduction method has white phosphorus reduction method, ascorbic acid reduction, sodium citrate
Reduction method and tannic acid-reduction of sodium citrate method etc..Those skilled in the art can come according to practical need, such as the partial size of nanogold
Determine specific reduction method, the present invention is herein without determination.
Cationic polymer solution of the invention can be obtained and cationic polymer is dissolved in solvent, used
Solvent can choose water or organic solvent, the organic solvent can non-exclusively be selected from methanol, ethyl alcohol or acetonitrile etc..
In a kind of specific embodiment of first aspect present invention, cationic polymer is poly- selected from but not limited to dendroid
Amide amine (PAMAM), hyperbranched poly propyleneimine (Poly (propyleneimine), PPI), hyperbranched polyethyleneimine
(PEI), at least one of polylysin (polylysine) and chitosan (chitosan)；In the another of first aspect present invention
In a kind of specific embodiment, cationic polymer is selected from dendroid daiamid；In another tool of first aspect present invention
In body embodiment, cationic polymer is selected from the dendroid daiamid in 1 generation, 2 generations, 3 generations and/or 4 generations.It is poly- for dendroid
The preparation method of amide amine, the present invention is herein without limiting.
In a kind of specific embodiment of first aspect present invention, in the Colorimetric System to be measured and the standard colorimetric
In system, the concentration of nanogold is 4.6 × 10-10M to 1.04 × 10-9M, preferably 6.0 × 10-10M to 1.0 × 10-9M；Sun from
The concentration of sub- polymer is 0.05-0.3uM, preferably 0.1-0.2uM.
In step (2), mixed when by the extraction phase to be measured of designated volume with nano-Au solution and cationic polymer solution
After conjunction, fatty acid of the nanogold in cationic polymer and extraction phase to be measured under the action of, can change color；Generally, exist
After nano-Au solution and cationic polymer solution and extraction to be measured are mixed, oscillation mixing about 3-5 minutes, color is basic
Stabilization no longer changes.In a kind of specific embodiment of the invention, extraction phase to be measured is gathered with nano-Au solution and cation
Polymer solution mixing, is particularly preferred as: first mixing extraction phase to be measured with nano-Au solution, and after mixing, it is poly- to add cation
Polymer solution；
Standard solution is mixed with nano-Au solution and cationic polymer solution, is particularly preferred as: first by standard solution
It is mixed with nano-Au solution, after mixing, adds cationic polymer solution.
In a kind of specific embodiment of first aspect present invention, especially using PAMAM as cationic polymer when,
PH value in the Colorimetric System to be measured and the Standard Colorimetric System is 4-10, is preferably 4.6-7.2 in pH value, in this range
Interior, system has response to the content of fatty acid, and more preferably pH value is 5.2, sensitivity highest at this time.In this pH value,
It is more suitable for carrying out the detection of fatty acid.
Inventor is on Research foundation above-mentioned further the study found that when nano-Au solution and cationic polymer is molten
After forming nanogold-cationic polymerization objects system, fatty acid is added in liquid mixing thereto, and the concentration of fatty acid influences PAMAM pairs
AuNPs rejection ability, concentration is bigger, and rejection ability is bigger, shows as the increase with fatty acid concentration, and state of aggregation AuNPs exists
Absorption value at 650nm reduces, meanwhile, the absorption value that dispersed AuNPs is in 520nm increases, as shown in Figure 1.It will inhibit energy
Power is with the maximum absorbance A of the AuNPs of dispersed520With the maximum absorbance A of state of aggregation650Ratio A520/A650It measures, and
The concentration of itself and the fatty acid (by taking oleic acid as an example) being added to be mapped, discovery is in a linear relationship in certain concentration range,
As shown in Figure 2.Illustrate that quantitative detection can be carried out to the content of fatty acid based on this principle.The research of ultraviolet spectra is further
It proves, if using colorimetric determination, with the ratio A at 520nm with absorbance at 650nm520/A650(y) to the dense of fatty acid
Degree (x, μM) make linear regression (5 concentration levels), the slope of calibration curve is close, as shown in table 1, that is, these four fatty acid
Sensitivity it is close.
1 carbon chain lengths of table are the detection range of linearity and calibration curve of C16-C18
Based on above-mentioned research, second aspect of the present invention provides a kind of quantitative determination side of free fatty acid in edible oil
Method comprising:
(A) N-1 part into N parts of extractants is separately added into the fatty acid standards of different known quantities, obtains N parts of fatty acid
The different standard solution of standard items content；The volume of N parts of standard solution is identical, N >=3；The fatty acid standards are selected from C16-
The fatty acid of C18；
(B) free fatty acid in N portions of edible oils is extracted respectively with N parts of standard solution, obtain N parts of sample to be tested extractions
Phase, wherein the volume of edible oil and the volume of standard solution are identical；
(C) from N parts of sample to be tested extraction phases, obtaining volume respectively is V1Test solution；By in N parts of test solution points
It is not mixed with nano-Au solution and cationic polymer solution, until color no longer changes, obtaining N parts of volumes is V0Sample to be tested
Solution；In all testing sample solutions, the concentration of nanogold is identical, and the concentration of cationic polymer is identical；
It (D) is V by volume1Extractant and nano-Au solution and cationic polymer solution mixing, until color is no longer
Variation, obtaining volume is V0Blank sample solution；The concentration and cationic polymerization of nanogold in the blank sample solution
The concentration of object is identical as testing sample solution respectively；
(E) uv-visible absorption spectra test is carried out to N parts of testing sample solutions and blank sample solution respectively；It determines
The ratio A of every part of testing sample solution absorbance at 520nm and at 650nm520/A650；
(F) with A520/A650For ordinate, with the content for the fatty acid standards being added in testing sample solution for horizontal seat
The value of the ordinate of the point of intersection of mark, the Standard entertion curve of drafting mapping sample solution, the abscissa and ordinate is sky
The A of white sample solution520/A650；And according to formulaDetermine the content of the free fatty acid in edible oil, wherein ρ table
Show the content of the free fatty acid in edible oil, c indicates the content of the point of intersection of Standard entertion curve and abscissa.It needs to illustrate
, the value of the abscissa of the point of intersection of the abscissa and ordinate is 0, represents the fatty acid being added in testing sample solution
The content of standard items is 0.
It should be noted that although cationic polymer makes the color of nano-Au solution become blue, but do not make to own
Nanogold particle generates reunion, is also partially in the nanogold particle of dispersed；Therefore, even if test system only includes extraction
Agent, nano-Au solution and cationic polymer solution, the ratio A of absorbance520/A650It also is not 0.Based on this, in the present invention
Technical solution in, by the A of blank sample solution520/A650The value of the ordinate of point of intersection as abscissa and ordinate is handed over
The value of abscissa at point remains as 0.
It should be noted that herein, the content of the free fatty acid in described edible oil refers in edible oil
The total content of free fatty acid, also referred to as acidity value.
In a kind of specific embodiment of second aspect of the present invention, fatty acid standards are selected from palmitinic acid, stearic acid, oil
At least one of acid and linoleic acid.
In a kind of specific embodiment of second aspect of the present invention, the extractant is the mixed solvent of methanol and water,
Preferably, the volume ratio of methanol and water is 2:1 in the extractant.
In a kind of specific embodiment of second aspect of the present invention, the grain of nanogold contained in the nano-Au solution
Diameter range is 10-50nm；Preferably 10-20nm, more preferably 13nm.
In a kind of specific embodiment of second aspect of the present invention, cationic polymer be selected from dendroid daiamid,
At least one of hyperbranched poly propyleneimine, hyperbranched polyethyleneimine, polylysin and chitosan；Preferably, cation is poly-
It closes object and is selected from dendroid daiamid；It is highly preferred that the dendroid that cationic polymer is selected from 1 generation, 2 generations, 3 generations and/or 4 generations is poly-
Amide amine.
In a kind of specific embodiment of second aspect of the present invention, in the testing sample solution, nanogold it is dense
Degree is 4.6 × 10-10M to 1.04 × 10-9M, preferably 6.0 × 10-10M to 1.0 × 10-9M；The concentration of cationic polymer is
0.05-0.3uM, preferably 0.1-0.2uM.
In a kind of specific embodiment of second aspect of the present invention, test solution is gathered with nano-Au solution and cation
Polymer solution mixing, specifically: test solution is mixed with nano-Au solution first, after mixing, it is molten to add cationic polymer
Liquid.Inventors have found that the linear relationship of ultraviolet spectral analysis is more preferable when being mixed in this order.
In a kind of specific embodiment of second aspect of the present invention, the Colorimetric System to be measured, the standard colorimetric body
PH value in system and the testing sample solution is 4-10, is preferably 4.6-7.2 in pH value, within this range, system is to fat
The content of acid has response, and more preferably pH value is 5.2, sensitivity highest at this time.In this pH value, it is more suitable for carrying out fat
The detection of acid.
In a kind of specific embodiment of second aspect of the present invention, the content of fatty acid standards in testing sample solution
≤10μM。
It should be noted that second aspect of the present invention content relevant to first aspect is referred to the note of first aspect
It carries, the present invention no longer repeats herein.
Explanation is needed further exist for, described " content " refers to certain ingredient included in predetermined substance herein
Amount, for example, including the amount etc. comprising fatty acid standards in the amount or testing sample solution of free fatty acid in edible oil.?
Herein, it there may come a time when that also referred to as content is concentration, especially occurs in same calculation formula or similar scene simultaneously
It, should be using concentration and content as identical concept, concentration and content unit having the same when content and concentration.
Free fatty acid determination method, may be implemented sxemiquantitative or quantitative in edible oil provided in an embodiment of the present invention
Measure the content of free fatty acid in edible oil.And it has the advantage that
(1) analysis time of the invention is short, can complete semi-quantitative analysis in a few minutes, compared with titration method, detection
More rapidly.
(2) present invention is few using the amount of organic solvent, environmentally protective.
(3) since AuNP has high molar extinction coefficient, the sensitivity of quantitative analysis of the present invention is very high.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is oleic acid concentration to the influence of nanogold-cationic polymerization objects system visible spectrum, wherein curve 1-6 is corresponding
System in, the concentration of nanogold is 6.5 × 10-10The concentration of M, PAMAM G1.0 are 0.13uM；The corresponding system of curve 1-6
In, the concentration of oleic acid is respectively as follows: 0,5uM, 10uM, 20uM, 35uM, 45uM；Curve 7 is concentration 6.5 × 10-10The nanogold of M is molten
Liquid；
Fig. 2 is the corresponding nanogold of oleic acid-cationic polymerization objects system A of various concentration520/A650Calibration curve
Figure, wherein the concentration of the nanogold in nanogold-cationic polymerization objects system is 6.5 × 10-10M, PAMAM G1.0's is dense
Degree is 0.13uM；
Fig. 3 is PAMAM G1.0 nuclear magnetic spectrogram (400MHz, CDCl prepared by embodiment 23, ppm),
Peak ownership: δ 2.35 (m, 8H, NCH 2CH2CONH),2.40(s,1,4H,NCH 2CH2N),2.65(m,8H,
CONHCH2CH 2NH2),2.81(m,8H,NCH2CH 2CONH),3.27(m,8H；CONHCH 2)。
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
It should be noted that although following embodiment is to be illustrated by taking PAMAM G1.0 as an example as cationic polymer
Technical solution of the present invention, still, for the PAMAM and hyperbranched poly third in the PAMAM of other whole algebra, especially 2-4 generation
Skill of the invention similarly may be implemented in the cationic polymers such as alkene imines, hyperbranched polyethyleneimine, polylysin and chitosan
Art scheme.
The preparation of 1 nano-Au solution of embodiment
By 1mL 1%HAuCl4It is added in the round-bottomed flask of 250mL, the distilled water three times of 99mL is added.It is stirred in magnetic force
Lower heating is mixed, rapidly joins 1% sodium citrate solution of 1.5mL thereto after boiling as reducing agent, to color by pale yellow
It is cooling to solution that color stops stirring after blue fades to claret (solution reflux 25min) again.This nano-Au solution is transferred to
In 100mL volumetric flask, it is protected from light and is stored in 4 DEG C of refrigerators after being diluted to graduation mark with water three times.This nano-Au solution concentration is used up
Spectrometry is measured as 8.5 × 10-10M。
The preparation of 2 PAMAM of embodiment
Using ethylenediamine as core, methanol is reaction dissolvent, is expanded outward using divergent method.At room temperature ethylenediamine first with excess
Methyl acrylate carry out Michael addition reaction 24 hours, product cleans in 50 DEG C of decompressions.The ester that the first step obtains again with mistake
The ethylenediamine of amount carries out ammoxidation 72 hours at room temperature, and product cleans in 72 DEG C of decompressions, obtains 0 generation dendroid and divides greatly
Son.It is alternately repeated Michael addition reaction and the available 1.0 generation dendritic macromole of ammoxidation.Product is cleaned, is done
Freezen protective after dry.By NMR spectrum (III -400MHz NMR spectrometer of A Bruker Advance,
Rheinstetten Germany) it is characterized.As a result as shown in Figure 3.Prepared PAMAM G1.0, which is prepared into concentration, is
The aqueous solution of 0.53uM.
The half-quantitative detection of free fatty acid in 3 edible corn oil of embodiment
Extractant is the mixed solution of methanol and water, and volume ratio is that 2:1. will (be in equal volume the extractant and food of 1mL)
It is mixed with corn oil, vibrates 3 minutes, separate extraction phase to be detected with edible corn oil after being layered.
Nano-Au solution prepared by 1.5mL embodiment 1 is added in the tool plug vial of 5mL, is added under agitation
The PAMAM G1.0 dendritic macromole that 490 μ L concentration are 0.53uM is added after being sufficiently mixed in 10 μ L extraction phases to be detected
(preparation of embodiment 2), is sufficiently mixed after colour stable, obtains Colorimetric System to be measured (PAMAM G1.0 in Colorimetric System to be measured
Ultimate density is 0.13uM, and the concentration of nanogold is 6.5 × 10-10M)。
The standard solution of free fatty acid, standard GB/T are prepared according to the edible oil acidity value upper limit of national Specification
19111-2003 provides that the acidity value (in terms of KOH, mg/g) of level-one, second level, three-level and level Four squeezing finished product edible corn oil is answered
No more than 0.2,0.3,1.0,3.0；Corresponding fatty acid molar concentration is respectively 4.46mM, 6.70mM, 22.3mM and
67.0mM.Using oleic acid as fatty acid standards, oleic acid is dissolved in extractant, 4 parts of standard solution of above-mentioned concentration are made.?
It is separately added into the nano-Au solution of the preparation of 1.5mL embodiment 1 in the tool plug vial of 5mL, 10 μ L mark is added under agitation
Quasi- solution, after being sufficiently mixed, the PAMAM G1.0 dendritic macromole that 490 μ L concentration are 0.53uM is added, and (embodiment 2 is made
It is standby), it is sufficiently mixed after colour stable, obtains 4 parts of Standard Colorimetric Systems (PAMAM G1.0 ultimate density in Colorimetric System to be measured
For 0.13uM, the concentration of nanogold is 6.5 × 10-10M)。
By the color contrast of Colorimetric System to be measured and 4 parts of Standard Colorimetric Systems it is found that the color of Colorimetric System to be measured is than one
The color of Standard Colorimetric System corresponding to grade corn oil is more blue, it is thus determined that content of fatty acid in measured edible corn oil
It is not above the content of fatty acid (acidity value) that level-one squeezing finished product uses corn oil.
The quantitative detection of free fatty acid in 4 edible corn oil of embodiment
Extractant is the mixed solution of methanol and water, volume ratio 2:1.It is separately added into 5 2mL tool plug vials
The extraction agent solution of 0.5mL oleic acid, wherein the concentration of oleic acid is respectively 0,400,800,1200,1600 μM.Again respectively to above-mentioned
0.5mL edible corn oil is added in bottle, is vibrated 3 minutes after mixing, extraction phase is separated with edible corn oil after being layered, is obtained
5 parts of sample to be tested extraction phases.The nano-Au solution of the preparation of 1.5mL embodiment 1 is separately added into the tool plug vial of 5mL,
The above-mentioned sample to be tested extraction phase of 10 μ L (test solution) is added under stirring condition, after being sufficiently mixed, 490 μ L concentration, which are added, is
The PAMAM G1.0 dendritic macromole (preparation of embodiment 2) of 0.53uM, is sufficiently mixed after colour stable, obtain 5 parts it is to be measured
Sample solution；
5mL tool plug vial in be successively added 1.5mL embodiment 1 preparation nano-Au solution, 10 μ L extractants and
490 μ L concentration are the PAMAM G1.0 dendritic macromole (preparation of embodiment 2) of 0.53uM, are sufficiently mixed after colour stable,
Obtain blank sample solution；
With ultraviolet-uisible spectrophotometer (UV-2450, Shimadzu, Japan) to each testing sample solution and blank sample solution
Absorbance measurement is carried out, uv scan range is 400-900nm, and with the ratio at 520nm with absorbance at 650nm
A520/A650(y) to oleic acid content (concentration) (x, μM) mapping in testing sample solution, the standard for drawing mapping sample solution adds
Enter curve, the value of the ordinate of the point of intersection of the abscissa and ordinate is the A of blank sample solution520/A650, value is
0.58；The value of abscissa is 0 μM；Determine 15.25 μM of content value c=... of the point of intersection of Standard entertion curve and abscissa；V1
=10 μ L；V0=2000 μ L；And according to formulaThe content for determining the free fatty acid in edible oil is 3050 μM.
1 standardized titration method of comparative example measures free fatty acid content in edible corn oil
The measurement of total fatty acid content is detected referring to standard GB/T/T 5530-2005:
(1) it accurately weighs a certain amount of edible corn oil (detecting oil used in embodiment 4) to be placed in conical flask, be added
95% ethyl alcohol of 50mL.
(2) phenolphthalein indicator of 2mL 1% is added, 95% ethyl alcohol preparation of phenolphthalein indicator allows food plant later
Oil and ethyl alcohol are sufficiently mixed.
(3) it is titrated with 0.01M standard potassium hydroxide solution, is shaken up while dripping, until solution becomes pink
Keep 30s constant.
Measurement three times, obtain the result is as follows:
The titration measurement of fatty acid in 2 edible corn oil of table
From the point of view of the testing result of embodiment 4 and documents 1, quantitative detecting method and conventional titration provided by the invention
The measurement result of method is close, therefore, can replace traditional titration for the content to the free fatty acid in edible oil into
Row detection.
Fatty acid determination method of dissociating in a kind of edible oil provided by the present invention is described in detail above.This
Specific embodiment is applied in text, and principle and implementation of the present invention are described, and the explanation of above embodiments is only used
Method and its central idea of the invention are understood in help.It should be pointed out that for those of ordinary skill in the art, not
, can be with several improvements and modifications are made to the present invention under the premise of being detached from the principle of the invention, these improvement and modification are also fallen into
The protection of the claims in the present invention.
Claims (15)
1. a kind of semiquantitative determination method of free fatty acid in edible oil characterized by comprising
(1) with the free fatty acid in extractant extraction edible oil, the extraction phase to be measured containing free fatty acid is obtained, wherein
The volume of the extractant and the volume of edible oil are identical；
(2) extraction phase to be measured for taking designated volume, it is mixed with nano-Au solution and cationic polymer solution, until face
Color no longer changes, and obtains Colorimetric System to be measured；
(3) color of the color of the Colorimetric System to be measured and Standard Colorimetric System is compared, determines in edible oil and dissociates
The content range of fatty acid；
Wherein, the Standard Colorimetric System determines by the following method:
The standard solution of different content of fatty acid, the rouge in the standard solution are prepared with the extractant from fatty acid standards
Fat acid content is it is known that the fatty acid standards are selected from the fatty acid of C16-C18；
The standard solution for taking the designated volume respectively mixes it with nano-Au solution and cationic polymer solution,
No longer change to color, obtains Standard Colorimetric System；The volume of the Standard Colorimetric System and the Colorimetric System to be measured is identical；
And in the Standard Colorimetric System nanogold and the concentration of cationic polymer respectively with nanogold in the Colorimetric System to be measured
It is identical with the concentration of cationic polymer；
The extractant is the mixed solvent of methanol and water.
2. the method as described in claim 1, which is characterized in that in step (3), determine containing for free fatty acid in edible oil
Range is measured, specifically: corresponding to standard solution of the color between two adjacent content of fatty acid of the Colorimetric System to be measured
Standard Colorimetric System color between when, determine that the content of free fatty acid in edible oil contains in described two adjacent fatty acid
Between amount.
3. the method as described in claim 1, which is characterized in that the color of the Standard Colorimetric System is recorded on carrier.
4. the method as described in claim 1, which is characterized in that the color of the Colorimetric System to be measured and Standard Colorimetric System
Color is indicated with the absorbance peak of Colorimetric System to be measured and the respective uv-visible absorption spectra of Standard Colorimetric System.
5. the method for quantitatively determining of free fatty acid in a kind of edible oil characterized by comprising
(A) N-1 part into N parts of extractants is separately added into the fatty acid standards of different known quantities, obtains N parts of Fatty acid standards
The different standard solution of product content；The volume of N parts of standard solution is identical, N >=3；The fatty acid standards are selected from C16-C18's
Fatty acid；
(B) free fatty acid in N portions of edible oils is extracted respectively with N parts of standard solution, obtain N parts of sample to be tested extraction phases,
In, the volume of edible oil and the volume of standard solution are identical；
(C) from N parts of sample to be tested extraction phases, obtaining volume respectively is V1Test solution；By N parts of test solution respectively with receive
Rice gold solution and cationic polymer solution mixing, until color no longer changes, obtaining N parts of volumes is V0Testing sample solution；
In all testing sample solutions, the concentration of nanogold is identical, and the concentration of cationic polymer is identical；
It (D) is V by volume1Extractant and nano-Au solution and cationic polymer solution mixing, until color no longer changes,
Obtaining volume is V0Blank sample solution；The concentration of nanogold in the blank sample solution and cationic polymer it is dense
It spends identical as testing sample solution respectively；
(E) uv-visible absorption spectra test is carried out to N parts of testing sample solutions and blank sample solution respectively；Determine every part
The ratio A of testing sample solution absorbance at 520nm and at 650nm520/A650；
(F) with A520/A650It is drawn for ordinate using the content for the fatty acid standards being added in testing sample solution as abscissa
The value of the ordinate of the point of intersection of the Standard entertion curve of mapping sample solution processed, the abscissa and ordinate is blank sample
The A of solution520/A650；And according to formulaDetermine the content of the free fatty acid in edible oil, wherein ρ indicates edible
The content of free fatty acid in oil, c indicate the content of the point of intersection of Standard entertion curve and abscissa；
The extractant is the mixed solvent of methanol and water.
6. method as claimed in claim 1 or 5, which is characterized in that the volume ratio of methanol and water is 2:1 in the extractant.
7. method as claimed in claim 1 or 5, which is characterized in that the partial size of nanogold contained in the nano-Au solution
Range is 10-50nm.
8. the method for claim 7, which is characterized in that the particle size range of nanogold contained in the nano-Au solution
For 10-20nm.
9. method according to claim 8, which is characterized in that the particle size range of nanogold contained in the nano-Au solution
For 13nm.
10. method as claimed in claim 1 or 5, which is characterized in that cationic polymer is selected from dendroid daiamid, surpasses
One of branched p 0 lypropylene imines, hyperbranched polyethyleneimine, polylysin and chitosan.
11. method as claimed in claim 10, which is characterized in that the cationic polymer is selected from dendroid daiamid.
12. method as claimed in claim 11, which is characterized in that the cationic polymer be selected from 1 generation, 2 generations, 3 generations and/or
The dendroid daiamid in 4 generations.
13. method as claimed in claim 1 or 5, which is characterized in that in the Colorimetric System to be measured, the standard colorimetric body
In system and the testing sample solution, the concentration of nanogold is 4.6 × 10-10M to 1.04 × 10-9Between M；Cationic polymer
Concentration between 0.05-0.3uM.
14. the method as described in claim 1, which is characterized in that the extraction phase to be measured for taking designated volume, by itself and nanometer
Gold solution and cationic polymer solution mixing, specifically: first extraction phase to be measured is mixed with nano-Au solution, after mixing, then
Cationic polymer solution is added；
The standard solution for taking the designated volume mixes it with nano-Au solution and cationic polymer solution, specifically
Are as follows: the standard solution of the designated volume is mixed with nano-Au solution first, after mixing, it is molten to add cationic polymer
Liquid.
15. method as claimed in claim 5, which is characterized in that
N parts of test solution are mixed with nano-Au solution and cationic polymer solution respectively, specifically: first described N parts is surveyed
Examination solution is mixed with nano-Au solution respectively, after mixing, then is separately added into cationic polymer solution.
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| KR101975308B1 (en) * | 2015-05-15 | 2019-05-07 | 가부시키가이샤 아타고 | Oil degradation meter and method for evaluating oil degradation |
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