The main ingredient in the edible vinegar is acetic acid (the content of acetic acid is more than 3.5%). The edible vinegar also contains a few other organic acids. According to national hygienic standard, free mineral acid (sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and other inorganic acid and oxalic acid) should not be detectable in the vinegar which is made by grains. However, the free mineral acid can be detected in the contaminated vinegar or that made up of inedible acid.

1. Application scope

It is suitable for rapid detection of free mineral acid in vinegar.

2. Ingredient of detection kit

  5 bags of thymol blue test paper (10pcs/bag)

  5 bags of methyl violet test paper (10pcs/bag)

3. Specification

  50 times for each kind of test paper

4. Using method and results

4.1 Thymol blue test paper (yellow color)

4.1.1 Use a capillary tube or a glass rod to dip a little vinegar sample onto the thymol blue test paper, or directly dip the test paper into the vinegar in sample cup, then observe the color. 

4.1.2 It is positive results that there are purple spots or purple circles (light purple inside the circles) on the test paper. It means the vinegar contains free mineral acid. It is negative results that there is not any purple spot or no purple circles (yellow or white inside the circles) on the test paper. Don’t observe the color variation until the test paper is a little dry when detecting the white vinegar.

4.2 Methyl violet test paper (purple color)

4.2.1 Use a capillary tube or a glass rod to dip a little vinegar sample onto the methyl violet test paper, or directly dip the test paper into the vinegar in sample cup, then observe the color.

4.2.2 It is positive results that the test paper turns blue or green (it means the vinegar contains free mineral acid). It is negative result that the color of test paper still keeps purple. 

5. Matters need attention

5.1 Store the detection kit at room temperature (4~30℃) in aeration-drying condition and keep away from children.

5.2 The methyl violet test plate (purple color) is suitable for detecting light color vinegar, like white vinegar. The thymol blue test plate (yellow color) is suitable for detecting some dark color vinegar, like mature vinegar.

6. Validity period: 2 years