Food Science Proyect HomeMade pH Indicator

PH Testing of Common Foods with a Homemade pH Indicator

            The pH scale is the system that measures the levels of acidic in substances. The pH measurement indicates the acidic and basic content within the scale of 0 to 14. A pH less than 7 is acidic and greater than 7 is basic, which 7 mean a neutral level. The less the number is the more acidic content it has. In addition water has a neutral pH of 7, chemical products that are mixed with water has either a high acidic content or a higher basic content as well ( In fact, cooking the purple cabbage in distilled water it helps to maintain a neutral pH liquid that I will use in my research as a homemade pH indicator.

            More over the pH of food varies not only with the kind of food, also environmental conditions could affect the final product in the same way (McWilliams, Margaret Food experimental perspectives 7edition). One of the particular characteristic the purple cabbage has in particular it is the content of a pigment molecule called flavin (anthocyanin). Substances with very acidic content will turn the molecule flavin in a red color. To the contrary neutral solutions will turn the flavin in a more purplish color, which basic solutions will change the color greenish-yellow. Consequently, the color it turns can be a good pH indicator on the different solutions listed below that I will use in my research (

•2 oz. orange juice

•2 oz. antacids dissolved in water

•2 oz. vinegar

•2 oz. baking soda dissolved in water

•2 oz. sprite or soda water

•2 oz. distilled water 

          In this particular picture from left to right the acidic, orange juice, vinegar, sprite, and the basics, antacid, and baking soda. After I add the cabbage juice to these different formulas, I noticed that the intense colors are the first 3 acids and they turn to the red family which the basic are more in the green family. As follow I present my pH Scale Table that will explain the result of this interesting investigation.




In Order of the most acidic pH level


Intensity   *

Vinegar   pH value 2 X 100,000

Shocking   Pink

3   Acidic

Orange   Juice value 3 X 10,000

Tangerine-Mango   solid because its texture from orange juice, a dense liquid.

2 Acidic

Soda   value 3 X 10,000

Clear   intense Fuchsia because the acidic from the sodium carbonate

3 Acidic

Baking   soda 9 X 0.01

Aqua   or turquoise

2   Basic

Antacid   Solution 10 X 0.001

Baby   blue

1   Basic

After this experiment, I notice that liquid that were denser like the orange juice and the baking soda, both with different pH indicator. The acidic orange juice which dense from it content and the basic baking soda, both apparently different one of the other. In the pH indicator level the orange juice has 3, water 7, and baking soda 9. The pH indicator specifies that both are in one of each other sides. As I mentioned this is a tool that indicates the acidic content based on color and intensity range consisting in the home made pH scale 1 to 3.



            The most acidic the content the better for food preserving are. The more acidic the content is the better for curing, or pickling. One of the main ingredients for pickling is the vinegar with a high acidic pH of 2 X 100.00. This process allows the vinegar extract the water from the product’s cell, penetrating more thoroughly giving to the cell more flavor, better texture and a long shelf life. One of the most common food preserved this way are pickling, pickles vegetables such as carrots, asparagus, and proteins like sausages, and eggs. (   


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