Estimation of pH

ESTIMATION OF pH OF MEAT

  • pH of a meat sample can be estimated by the following methods
    • Litmus paper method
    • Nitrazine yellow indicator test
    • pH meter

Nitrazine yellow indicator test

  • The given sample of meat is placed in a porcelain dish and the nitrazine yellow indicator solution (1: 10,000) is poured.
  • The change in colour of the solution will give an indirect range of pH.
  • Meat with the pH of 6.0 produces a yellow colouration and classified as one possessing good durability.
  • Meat with the pH of 6.4 produces an olive green colouration and is classified as one possessing insufficient durability and is a suspect and the pH of 6.8 shows a bluish violet colouration and it is considered to be of very low durability and it is unfit for food.

Estimation of pH by pH meter

  • Measurement of pH using pH meter is accomplished by determining the potential developed by an electrical cell.
  • The cell consists of an electrode system immersed in a test solution.
  • The electrode system is pH sensitive and develops an electrical potential proportional to the pH of the solution in which it is immersed.
  • The pH meter is standardized by adjusting the pH meter to the value of the buffer solution.
  • Then the electrode after proper washing is immersed in the test solution.
  • pH meter will then indicate the pH value of the test solution directly.
  • The pH of the given meat sample can be estimated by directly placing the electrode into the muscles of the carcass or the muscles can be converted into a slurry and pH is determined by dipping the electrode in it.
  • 10 gm of meat is minced with 50 ml of distilled water for 30-60 seconds.
  • The slurry is taken into a beaker and the electrode is dipped into the slurry and pH is estimated.

Precautions to be taken

  • Put on the pH meter by connecting it to the mains.
  • Always keep the electrodes dipped or immersed in glass distilled water.
  • Wipe the electrode with blotting paper and wash with distilled water and introduce it into the meat slurry before reading the pH.
  • Take the reading the when the reading becomes stable for 30-60 seconds.
Last modified: Tuesday, 7 September 2010, 10:37 AM