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
-- the 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 20ยฐC 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 20ยฐC, the Brix is usually consider equivalent
to the percentage of sucrose (sugar) in the solution
(60ยฐ Brix is equivalent to a sugar content of 60%).
7. o 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)
๏ข The test to determine the โPercent Juice Contentโ
is important to determine the quality of the fruit.
๏ข If to fruit is under or over-ripe there can be less
juice, which affects eating quality
๏ข 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
๏ข 1ST.. Equipment
๏ข Refractometer
Procedure
1. Collect a refractometer (these should be handled carefully as
they are expensive!)
2. Ensure the refractometer prism surface is clean and dry
3. Place a small amount of fresh juice (a couple of drops is
sufficient) onto the prism of the refractometer.
4. . Look through the eyepiece while pointing the prism in the
direction of good light (not directly at the sun).
5. . Focus and take the reading of where the base of the blue
colour sits on the scale and record the % percentage sugar
(ยฐBrix).
10. ๏ข 6. Clean the refractometer immediately with a damp
tissue, and dry thoroughly.
Calculation of TSS
3 trial sample
Trial 1 trial 2 +๐ก๐๐๐๐ 3
3 trials
=results of brix
+
