Tta & Ph

pH AND TTA

Research Department

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TECHNICAL _BULLETIN

Editor Gur Ranhotra I Volume XI, Issue 5 I May, 1989

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HYDROGEN ION CONCENTRATION (pH) AND TOTAL TITMTABLE ACIDITY TESTS

Roy Sutherland Bakery Technical Service Mlburn, GA 30247 INTRODUCTION The pH and total titratable acidity (TTA) tests are two measurements which can provide an indication of the quality of yeast raised bakery foods to be produced. These tests have been used widely in the food industry for many years to control quality, but it was not until the early 1960s that bakers also began to use these tests. The exact procedure for using pH and TTA tests for monitoring the rate of bread dough fermentation was first outlined by Clarence Farrell (1) and later refined and introduced by Felix Cottle. Their methods are now widely used in the baking industry. DEFINING pH Briefly, pH is a measure of the degree of acidity or alkalinity of a substance. As a result of a mathematical conversion, a numerical scale of 0 to 14, known as the pH scale (Table I), was established to express pH values, pH 7.0 being the neutral point on this scale, or the pH of pure water. Numbers decreasing from 7.0 express increasing acid strength, while numbers increasing from 7.0 express increasing alkalinity. A unit change in pH represents a ten fold change in acidity or alkalinity. Thus, compared with a solution of pH 5, a solution of pH 4 is ten times as acid, pH 3 a hundred times as acid, and pH 2 a thousand times as acid. DEFINING TTA TTA is the term used to describe the amount of acid in a substance. TTA is expressed in milliliters (ml) and represents the number of ml of 0.1 normal sodium hydroxide (NaOH) needed to neutralize a specific amount of an acid solution to a pH of 6.6. EQUIPMENT NEEDED FOR pH AND TTA TESTS

‘IABLE I THE pH SCALE

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9 10 11 12 13 14

Acidic pH

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A Neutral PH

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Alkaline pH

For pH Test: pH Meter. A pH meter has one or two...