Titratable acidity and Total Soluble Solids

a discussion on TA and TSS

1. Titratable Acidity and Total Soluble Solids Reporters : Emma Benilyn Ma ñ ara Ma. Theresa Badilla

2. Titratable Acidity (TA) -- Titratable acidity is a total amount of acid in the solution as determined by the titration using a standard solution of sodium hydroxide (titrant). -- Titratable acidity is determined by neutralizing the acid present in a known quantity (weight or volume) of food sample using a standard base. The endpoint for titration is usually either a target pH or the color change of a pH-sensitive dye, typically phenolphthalein. --   Titratable acidity of a solution is an approximation of the solution's  total acidity. -- The  titratable acidity of a solution is measured by reacting the acids present with a base such as sodium hydroxide( NaOH ) to a chosen endpoint, close to neutrality, as indicated by an acid sensitive colour indicator.

3. There are two methods to express food acidity : Titratable acidity -- measures the total acidity but does not measure the strength of the acids. Hydrogen ion concentration or pH -- t he pH indicates the strength of the acid condition. pH - ( pH = -log[H + ] ) the equilibrium measure of hydrogen ion concentration in a, e.g juice or wine.

4. how to do titration of acid Method 1 . Mix the milk sample thoroughly by avoiding incorporation of air. 2 . Transfer 10 gm milk to conical flask or beaker . 3 . Add equal quantity of distilled water . 4 . Add 3-4 drops of phenolphthalein indicator and stir 5 . Rapidly titrate the contents with 0.1 N NaOH solution, continue to add alkali drop by the drop and stirring the content till first definite change to pink colour . 6 . Note down the final burette reading.

5. TOTAL SOLUBLE SOLID (TSS) -Measure the sugar content of sugar solutions (honey, juices,syrup ) which the sugar is the major component using refractometer -Total soluble solids content of a solution is determined by the index of refraction. This is measured using a refractometer , and is referred to as the degrees Brix . -Brix is the term used when a refractometer equipped with a scale,based on the relationship between refractive indices at 20°C and the percentage by mass of total soluble solids of a pure aqueous sucrose solution.

6. -This tests the solids concentration of a sucrose containing solution . -It is widely used during fruit and vegetable processing to determine the concentration of sugar in the products . - Sugar concentration is expressed in degrees Brix. At 20°C, the Brix is usually consider equivalent to the percentage of sucrose (sugar) in the solution (60° Brix is equivalent to a sugar content of 60%).

7. Two instrument used to measure the total soluble solid ( tss ) - Refractometer - AN INSTRUMENT THAT MEASURES THE REFRACTIVE INDEX THAT IS TAKEN AS A CONSTANT FOR PURE SUBSTANCE UNDER SPECIFIC CONDITIONS OF TEMPERATURE AND PRESSURE - ABBE HAND REFRACTOMETER - COMMONLY USED WHICH ALLOWS REFRACTIVE INDEX TO BE READ DIRECTLY,ONLY FEW DROPS OF LIQUID ARE NEEDED

8. IMPORTANCE OF CALCULATING THE PRCENTAGE OF TSS ( JUICE IN THE FRUIT) The test to determine the ‘ Percent Juice Content’ is important to determine the quality of the fruit . If to fruit is under or over-ripe there can be less juice, which affects eating quality Determining the total soluble solids (Brix) is an important measurement taken in a wide range of crops.

9. THE FOLLOWING PROCEDURE ON HOW TO CALCULATE THE BRIX 1 ST .. Equipment R efractometer Procedure Collect a refractometer (these should be handled carefully as they are expensive !) Ensure the refractometer prism surface is clean and dry Place a small amount of fresh juice (a couple of drops is sufficient) onto the prism of the refractometer . . Look through the eyepiece while pointing the prism in the direction of good light (not directly at the sun ). . Focus and take the reading of where the base of the blue colour sits on the scale and record the % percentage sugar (°Brix).

10. 6. Clean the refractometer immediately with a damp tissue, and dry thoroughly . Calculation of TSS 3 trial sample Trial 1 trial 2 3 trials results of brix