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A test paper for quickly judging rice freshness and its application

A technology of freshness and test paper, which is applied in the direction of analyzing materials through chemical reactions and observing the influence of chemical indicators on materials, etc. It can solve problems such as water absorption reduction, darkening of color, and viscosity drop. Achieve the effects of simplifying the method of adsorbing rice volatiles, avoiding interference with the production of volatiles, and simple preparation process

Active Publication Date: 2015-11-18
李欣
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

With the extension of conventional storage and preservation time of rice, the food will obviously deteriorate, the color will darken, the aroma will disappear, the acidity will increase, the sour taste of bran will appear, the viscosity will decrease, the water absorption will decrease, the water holding capacity will decrease, the porridge will not thicken, and the eating quality will decrease, etc. question

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Step 1. Immerse blank filter paper in 2,4-dinitrophenylhydrazine hydrochloric acid-methanol solution (2,4-dinitrophenylhydrazine concentration is 5 mg / L, hydrochloric acid volume fraction is 1.5%) at room temperature for 2 minutes, Then take it out, let it dry for 30 seconds, and cut out two test papers with a size of 2cm×5cm to obtain test paper A and test paper B;

[0034] Step 2. Weigh 10g of rice sample (place of origin: Guangdong; conventional storage for 2 years), put the rice sample and test paper A into 150mL conical flask A, and put test paper B into 150mL conical flask B separately;

[0035] Step 3: Seal the mouths of the two Erlenmeyer flasks with tin foil, and then heat the two Erlenmeyer flasks in a 50°C water bath for 10 minutes;

[0036] Step 4, take out test paper A and test paper B, and read the test results. Compared with test paper B: test paper A is obviously yellow, and the rice sample is old rice.

[0037] Test result verification:

[0038] (1) P...

Embodiment 2

[0042] Step 1. Immerse blank filter paper in 2,4-dinitrophenylhydrazine hydrochloric acid-methanol solution (2,4-dinitrophenylhydrazine concentration is 25mg / L, hydrochloric acid volume fraction is 1.5%) at room temperature for 1.5min , then take it out, let it dry for 25 seconds, cut two test papers with a size of 3cm×6cm, and obtain test paper A and test paper B;

[0043] Step 2: Weigh 15g of rice sample (origin: Guangdong; regular storage for half a year), put the rice sample and test paper A into 150mL conical flask A, and put test paper B into 150mL conical flask B separately;

[0044] Step 3: Seal the mouths of the two Erlenmeyer flasks with tin foil, and then heat the two Erlenmeyer flasks in a 60°C water bath for 20 minutes;

[0045] Step 4, take out test paper A and test paper B, and read the test results. Compared with test paper B: test paper A obviously does not show color, and the rice sample is new rice.

[0046] Test result verification:

[0047] (1) Prepare t...

Embodiment 3

[0051] Step 1: Immerse the blank filter paper in the hydrochloric acid-methanol solution of 2,4-dinitrophenylhydrazine (2,4-dinitrophenylhydrazine concentration is 50mg / L, the volume fraction of hydrochloric acid is 1.5%) at room temperature for 1min, Then take it out, let it dry for 35 seconds, and cut out 4 test papers with a size of 4cm×8cm to obtain test paper A, test paper B, test paper C and test paper D;

[0052] Step 2: Weigh 20g of newly harvested rice (origin: Guangdong) (rice sample A), 20g of rice stored for 1 year (rice sample B, produced in Hunan), and 20g of rice stored for 2 years (rice sample C, produced in Jiangxi ), then put rice sample A and test paper A into 150mL Erlenmeyer flask A, rice sample B and test paper B into 150mL Erlenmeyer flask B, rice sample C and test paper C into 150mL Erlenmeyer flask C, and test paper D separately into a 150mL Erlenmeyer flask D;

[0053] Step 3: Seal the mouths of the four Erlenmeyer flasks with tin foil, and then heat...

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PUM

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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 [0001] The invention belongs to the field of food safety testing, and in particular relates to a test paper for quickly judging the freshness of rice and its application. Background technique [0002] The content of volatile aldehydes in rice (also known as rice) is an important indicator for evaluating the taste and freshness of rice, and it has become a research hotspot at home and abroad in recent years. There is a big difference in the content of volatile components between fresh rice and aged rice after a period of storage. For example, aged rice contains more valeraldehyde and acetaldehyde than fresh rice, and carboxyl compounds with 3 to 6 carbon atoms in aged rice account for the total odor components. 30%, which is 10 times that of new rice. These carboxyl compounds play a bad role in rice odor. With the extension of conventional storage and preservation time of rice, the food will obviously deteriorate, the color will darken, the aroma will disapp...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/78
Inventor 李欣陈威
Owner 李欣