CN103454272A - Test paper for rapidly judging rice freshness and application of test paper - Google Patents
Test paper for rapidly judging rice freshness and application of test paper Download PDFInfo
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Abstract
The invention discloses test paper for rapidly judging rice freshness and application of the test paper. The test paper is prepared by adopting a method comprising the following steps of: immersing blank filter paper in an aldehydes material absorbing agent at room temperature for 1-2min, then taking out, airing, and cutting into a set size to obtain the test paper. The test paper is used for judging the rice freshness by adopting the specific steps: placing a rice sample and the test paper in a test bottle, sealing a bottle opening of the test bottle by using a tin foil, then heating the test bottle for 10-60min at the temperature of 50-70 DEG C; taking the test paper out, reading a testing result, comparing with contrast test paper: if the test paper does not develop, indicating that a rice sample is fresh rice; if the test paper shows yellow, indicating that the rice sample is aging rice. The rice freshness is tested by using the test paper prepared by the invention, thus an existing method for adsorbing rice volatile matters is simplified, developing reaction is synchronously carried out; the test paper is simple, effective and easy to implement, and can be widely applied to rice processors.
Description
Technical field
The invention belongs to the food safety detection field, be specifically related to a kind of test paper and application thereof of quick judgement rice new-old degree.
Background technology
Volatile Aldehyde components content in rice (also claiming rice) is the important indicator of estimating White Rice Taste, freshness, is the study hotspot of recent domestic.Fresh rice and the old rice volatile component content after storage a period of time have bigger difference, and as old rice contains more valeral and acetaldehyde than fresh rice, in old rice, the carboxyl compound of 3～6 carbon atoms accounts for 30% of total odour component, is 10 times of new rice.These carboxyl compounds play ill-effect to the rice smell.Rice is along with the prolongation of conventional preservation and freshness time, the obvious variation of food, and color and luster is dimmed, fragrance disappears, acidity increases, and occurs that furancarboxylic acid flavor and viscosity descend, water absorbing capacity reduces, retention ability goes down, and the problems such as not thick soup, edible quality reduction cook congee.Therefore, for rice processing enterprises, find a kind of reliably, it is most important that easy means are screened fresh raw material.
Summary of the invention
For solving the shortcoming and defect part of prior art, primary and foremost purpose of the present invention is to provide a kind of test paper of quick judgement rice new-old degree.
Another object of the present invention is to provide the application process of above-mentioned test paper, this test paper carries out the judgement of rice new-old degree based on aldehyde material total content in rice, simple to operate, accuracy is high.
For achieving the above object, the present invention adopts following technical scheme:
A kind of test paper of quick judgement rice new-old degree, this test paper prepares by the following method and obtains: under room temperature, blank filter paper is immersed to 1～2min in the aldehyde material absorbing agent, the 25～35s that then takes out, dries in the air, be cut into the setting size, obtains described test paper.
The of short duration purpose of drying of 25～35s is to keep test paper macroscopic moistening, not bone dry; Select directly to dry, the one, because the aldehyde material absorbing agent is not suitable for baking oven, general baking temperature can not be over 30 ℃; The 2nd, for convenience of on-the-spot detection.Described blank filter paper is commercially available common filter paper.
Room temperature of the present invention is 15 ℃～30 ℃.
Preferably, hydrochloric acid-methanol solution that described aldehyde material absorbing agent is DNPH.
Wherein methyl alcohol is as solvent; The effect that adds hydrochloric acid is to keep acid medium.
Preferably, in described aldehyde material absorbing agent, the concentration of DNPH is 5～50mg/L, and in the aldehyde material absorbing agent, the volume fraction of hydrochloric acid is 1.5%.
In the present invention, the concentration of DNPH is 5～50mg/L, can well be controlled at DNPH pickup on test paper at 40 μ g/10cm
2above, thus the sensitivity of assurance test paper.
Preferably, described test paper is strip, is of a size of (2～5) cm * (5～8) cm.
Above-mentioned test paper is applied to judge the rice new-old degree; Concrete steps are as follows:
Step 1, get two test paper of judging fast the rice new-old degree, and Rice Samples and test paper A are put into to test bottle A, and test paper B is put into separately to test bottle B;
Step 2, respectively by test bottle A and test bottle B sealing bottleneck, then heat 10～60min by two test bottles in 50～70 ℃ with tinfoil;
Step 3, take out test paper A and test paper B, the read test result, and with test paper, B compares: if test paper A does not develop the color, Rice Samples is new rice; If test paper A displaing yellow, Rice Samples is old rice.
New-old degree described in the present invention refers to the freshness of rice, the new-old degree of rice is affected by storage condition and storage time, along with storage time extends, the bad change of the continuous ageing of rice, cause Cooking Quality to descend, the inventive method belongs to carries out preliminary screening method to the rice new-old degree, is divided into Xin meter and old rice while detecting new-old degree; During detection, if the color displaing yellow of test paper illustrates that in Rice Samples, the aldehyde material total concentration is not less than 20mg/kg, sample is old rice; When if test paper does not develop the color, illustrate that in Rice Samples, the aldehyde material total concentration is lower than 20mg/kg, sample is new rice.
The present invention uses tinfoil to be sealed bottleneck, can avoid interference volatile matter and produce, and tinfoil is easy is easy to get, can reuses.
In test process, the test paper purpose of blank is the environmental pollution that may exist in test environment in order to eliminate, the test paper of blank does not develop the color under normal circumstances, if yellow occurred, will get rid of after aldehyde material that operating environment exists pollutes and retest.
Preferably, Rice Samples described in step 1 is 10～20g.
Above-mentioned preferred sample quality not only facilitates detection but also can guarantee the sensitivity detected.
Preferably, in step 2, the mode by water-bath is heated.
Adopt the mode of water-bath to detect, can make sample be heated more even.
Mechanism of the present invention is: in test paper of the present invention, contain 2, the 4-dinitrophenylhydrazine, therefore, when if detected rice is old rice, owing in old rice, can containing valeral and acetaldehyde, and aldehydes mass-energy and 2, the 4-dinitrophenylhydrazine generates yellow phenylhydrazone, test paper can show yellow, by synchronously carrying out chromogenic reaction, thereby effectively judges the new-old degree of rice.And, by DNPH column front derivation-high performance liquid chromatography of the prior art, verified, the minimum aldehyde material concentration that test paper of the present invention can detect is 20mg/kg, with above-mentioned chromatographic testing result coincidence rate be 97.2%.
Concrete verification method is as follows: with the standard series of DNPH solution preparation hexanal, make on its abundant reactor to vibrate 10s, (test condition: ultraviolet detects high effective liquid chromatography for measuring, wavelength 360nm; Mobile phase, acetonitrile+water (volume ratio is 60:40); The C18 post), drawing standard curve; Then the test strips after detecting is placed in to 2mL acetonitrile wash-out 1～2min, measures the 360nm light absorption value, aldehyde material total amount in calculation sample.
Compared with prior art, the present invention has the following advantages and beneficial effect:
The present invention is the carrier as the aldehyde material absorbing agent with commercially available filter paper, prepares a kind of test paper that can detect the rice new-old degree, and this test paper preparation technology is simple, easy to detect, highly sensitive.
The present invention carries out the detection of rice new-old degree by prepared test paper, has simplified the method for existing absorption rice volatile matter, synchronously carries out chromogenic reaction, and simple, effective, easily enforcement, can be widely used in rice processing enterprises.
The testing result of test paper of the present invention, the fatty acid value content detected in Rice Samples with method according to GB/T20569-2006 is contrasted, coincidence rate is 95.6%, i.e. old rice displaing yellow result, for described in GB/T20569-2006 slightly should not deposit or severe should not be deposited.
Embodiment
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment 1
Step 1, under room temperature immerse blank filter paper the hydrochloric acid-methanol solution (2 of DNPH, 4-dinitrophenylhydrazine concentration is 5mg/L, and the volume fraction of hydrochloric acid is 1.5%) middle 2min, 30s then takes out, dries in the air, cut out lower two test paper that are of a size of 2cm * 5cm, obtain test paper A and test paper B;
Step 2, take the 10g Rice Samples (place of production: Guangdong; Conventional stored condition 2 years), Rice Samples and test paper A are put into to 150mL triangular flask A, test paper B is put into separately to 150mL triangular flask B;
Step 3,, then be placed in 50 ℃ of water-baths by two triangular flasks and heat 10min respectively by two triangular flask sealing bottlenecks with tinfoil;
Step 4, take out test paper A and test paper B, the read test result, and with test paper, B compares: test paper A obviously is yellow, and Rice Samples is old rice.
The testing result checking:
(1) with the standard series of DNPH solution preparation hexanal, make on its abundant reactor to vibrate 10s, (test condition: ultraviolet detects high effective liquid chromatography for measuring, wavelength 360nm; Mobile phase, acetonitrile+water (volume ratio is 60:40); The C18 post), drawing standard curve; Then the test strips after detecting being placed in to 2mL acetonitrile wash-out 1～2min, measuring the 360nm light absorption value, calculate aldehyde material total amount 56mg/kg in sample, is old rice of the present invention.Illustrate that the present embodiment detection paper result is correct.
(2) detect the fatty acid value content in Rice Samples according to the method for GB/T20569-2006, detect and obtain fatty acid value in Rice Samples: 38 (mg/100g)/(KOH/ dry), for severe should not be deposited.
The present embodiment detection paper result, the fatty acid value content detected in Rice Samples with method according to GB/T20569-2006 is contrasted, and result is consistent.
Embodiment 2
Step 1, under room temperature immerse blank filter paper the hydrochloric acid-methanol solution (2 of DNPH, 4-dinitrophenylhydrazine concentration is 25mg/L, and the volume fraction of hydrochloric acid is 1.5%) middle 1.5min, 25s then takes out, dries in the air, cut out lower two test paper that are of a size of 3cm * 6cm, obtain test paper A and test paper B;
Step 2, take the 15g Rice Samples (place of production: Guangdong; Conventional stored condition half a year), Rice Samples and test paper A are put into to 150mL triangular flask A, test paper B is put into separately to 150mL triangular flask B;
Step 3,, then be placed in 60 ℃ of water-baths by two triangular flasks and heat 20min respectively by two triangular flask sealing bottlenecks with tinfoil;
Step 4, take out test paper A and test paper B, the read test result, and with test paper, B compares: test paper A does not obviously develop the color, and Rice Samples is new rice.
The testing result checking:
(1) with the standard series of DNPH solution preparation hexanal, make on its abundant reactor to vibrate 10s, (test condition: ultraviolet detects high effective liquid chromatography for measuring, wavelength 360nm; Mobile phase, acetonitrile+water (volume ratio is 60:40); The C18 post), drawing standard curve; Then the test strips after detecting being placed in to 2mL acetonitrile wash-out 1～2min, measuring the 360nm light absorption value, calculate aldehyde material total amount 18mg/kg in sample, is new rice of the present invention.Illustrate that the present embodiment detection paper result is correct.
(2) detect the fatty acid value content in Rice Samples according to the method for GB/T20569-2006, detect and obtain fatty acid value in Rice Samples: 22 (mg/100g)/(KOH/ dry), be advisable and deposit.
The present embodiment detection paper result, the fatty acid value content detected in Rice Samples with method according to GB/T20569-2006 is contrasted, and result is consistent.
Embodiment 3
Step 1, under room temperature, blank filter paper is immersed to 2, hydrochloric acid-the methanol solution (2 of 4-dinitrophenylhydrazine, 4-dinitrophenylhydrazine concentration is 50mg/L, the volume fraction of hydrochloric acid is 1.5%) middle 1min, then the 35s that takes out, dries in the air, cut out lower 4 test paper that are of a size of 4cm * 8cm, obtains test paper A, test paper B, test paper C and test paper D;
Step 2, (place of production: Guangdong) (Rice Samples A), 20g deposit rice (the Rice Samples B of 1 year to take respectively the new rice of gathering in the crops of 20g, Hunan, the place of production), 20g deposits rice (the Rice Samples C of 2 years, Jiangxi, the place of production), then Rice Samples A and test paper A are put into to 150mL triangular flask A, Rice Samples B and test paper B are put into to 150mL triangular flask B, Rice Samples C and test paper C are put into to 150mL triangular flask C, test paper D is put into separately to 150mL triangular flask D;
Step 3,, then be placed in 70 ℃ of water-baths by 4 triangular flasks and heat 60min respectively by 4 triangular flask sealing bottlenecks with tinfoil;
Step 4, take out test paper A, test paper B, test paper C and test paper D, the read test result, and with test paper, D compares: test paper A does not develop the color, test paper B displaing yellow, test paper C shows buff.
The testing result checking:
(1) with the standard series of DNPH solution preparation hexanal, make on its abundant reactor to vibrate 10s, (test condition: ultraviolet detects high effective liquid chromatography for measuring, wavelength 360nm; Mobile phase, acetonitrile+water (volume ratio is 60:40); The C18 post), drawing standard curve; Then test paper A, test paper B, test paper C after detecting are placed in to 2mL acetonitrile wash-out 1～2min, measure the 360nm light absorption value, calculate aldehyde material total amount in sample A, B, C and be respectively 8mg/kg, 23mg/kg and 61mg/kg, therefore Rice Samples A is new rice of the present invention, Rice Samples B is old rice of the present invention, and Rice Samples C is old rice of the present invention.Illustrate that the present embodiment detection paper result is correct.
(2) detect the fatty acid value content in above-mentioned Rice Samples according to the method for GB/T20569-2006, detect and obtain fatty acid value in Rice Samples A: 16 (mg/100g)/(KOH/ dry), be advisable and deposit, conform to the detection paper result; Fatty acid value in Rice Samples B: 27 (mg/100g)/(KOH/ dry), be advisable and deposit; Fatty acid value in Rice Samples C: 38 (mg/100g)/(KOH/ dry), for severe should not be deposited, conform to the detection paper result.
Above-described embodiment is preferably embodiment of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection scope of the present invention.
Claims (7)
1. a test paper of judging fast the rice new-old degree, it is characterized in that, described test paper prepares by the following method and obtains: under room temperature, blank filter paper is immersed to 1～2min in the aldehyde material absorbing agent, 25～35s then takes out, dries in the air, be cut into the setting size, obtain described test paper.
2. test paper according to claim 1, is characterized in that, hydrochloric acid-methanol solution that described aldehyde material absorbing agent is DNPH.
3. test paper according to claim 2, is characterized in that, in described aldehyde material absorbing agent, the concentration of DNPH is 5～50mg/L, and in the aldehyde material absorbing agent, the volume fraction of hydrochloric acid is 1.5%.
4. test paper according to claim 1, is characterized in that, described test paper is strip, is of a size of (2～5) cm * (5～8) cm.
5. the application of the described test paper of claim 1～4 any one in judging the rice new-old degree, is characterized in that, described test paper is for judging that the concrete steps of rice new-old degree are as follows:
Step 1, get two test paper, and Rice Samples and test paper A are put into to test bottle A, and test paper B is put into separately to test bottle B;
Step 2, respectively by test bottle A and test bottle B sealing bottleneck, then heat 10～60min by two test bottles in 50～70 ℃ with tinfoil;
Step 3, take out test paper A and test paper B, the read test result, and with test paper, B compares: if test paper A does not develop the color, Rice Samples is new rice; If test paper A displaing yellow, Rice Samples is old rice.
6. the application of test paper according to claim 5 in judging the rice new-old degree is characterized in that Rice Samples described in step 1 is 10～20g.
7. the application of test paper according to claim 5 in judging the rice new-old degree is characterized in that the mode by water-bath in step 2 is heated.
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Cited By (2)
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| CN105424696A (en) * | 2016-01-05 | 2016-03-23 | 北京北大明德科技发展有限公司 | Detection test paper for fast distinguishing fresh degree of rice and detection method |
| CN112921505A (en) * | 2021-02-24 | 2021-06-08 | 福州大学 | Preparation method of electrospinning blotting chromogenic membrane with high efficiency and selectivity on hexanal |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105424696A (en) * | 2016-01-05 | 2016-03-23 | 北京北大明德科技发展有限公司 | Detection test paper for fast distinguishing fresh degree of rice and detection method |
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| CN112921505A (en) * | 2021-02-24 | 2021-06-08 | 福州大学 | Preparation method of electrospinning blotting chromogenic membrane with high efficiency and selectivity on hexanal |
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