Total Titratable Acidity (TTA)
What is Total Titratable Acidity (TTA)?
Total titratable acidity (TTA) is a measure of the amount of acid (single or mixture of acids) present in a substance. The basis for TTA determination is the amount of strong base required to neutralize an acid based on the amount rather than its strength.
The acidity of food products is a consequence of their formulation including the amount and type of ingredients, additives and preservatives used as well as processing conditions. Several baking operations rely on the TTA parameter to control various processes such as:
- Yeast fermentation
- Flavor development
- Product formulation
How does it work?
Analytically or chemically speaking, TTA is reported in milliliters (mL) of a 0.1 normal* (N) solution of sodium hydroxide (NaOH) required to titrate (neutralize) a given amount of material to a pH end point of 6.6.1
The difference between TTA and pH
TTA and pH are two interrelated concepts that deal with acidity. However, they are measured differently and the results give different insights into the composition of the food sample.2 pH is used to measure how strong or weak acids are by measuring the concentration of hydrogen ions (H+) that acids release upon dissociation in an aqueous solution (using a logarithmic scale from 0 to 14). The concentration of an acid, expressed as TTA, in water does not necessarily correspond to the concentration of the hydrogen ions present in the solution.
pH is also used to determine how acidic or alkaline foods are. It is important to note that the majority of food materials and ingredients are acidic in nature, so they have at least a minimum amount of titratable acidity and a pH less than 7.
The following is an overview of TTA and its relationship with pH and breadmaking processes using a sponge and dough system:
|Process step||TTA (mL)1||pH1||Comments|
|Bread sponge||4.5–4.6||4.8–4.9||At the end of sponge fermentation, sponge becomes more acidic due to fermentation. More base is needed to titrate organic acids produced and pH is lower than that of dough.|
|After dough mixing (at makeup)||3.9– 4.0||5.2–5.6||After the addition of fresh flour, dilution with dough side water, milk solids, vital wheat gluten, etc., the dough loses some of its initial acidity. TTA decreases and pH increases approaching neutral values.|
|After proofing||5.0–5.5||4.9–5.0||Acidity builds up slightly after proofing, and more mL of base are needed to neutralize the acid produced to the end point.|
|Baked good (bread)||3.8–3.9||5.1–5.2||Baking evaporates some water, alcohol and volatiles as well as water-soluble organic compounds. As a consequence, bread loses some of the acidity gained during final proofing.|
TTA as fermentation control mechanism
TTA is very useful for measuring total acids produced by yeast and lactic acid bacteria fermentation. In this application, TTA is used to assess fermentation rate and determine when doughs and preferments are fermented and matured to optimum levels.
Unlike pH, TTA is not impacted by the presence of buffers in the sample being analyzed. This is a very useful tool for controlling the fermentation of bakery systems such as plastic sponges, sourdough, poolish and flour brews containing natural buffering ingredients (e.g. flour, eggs, vital wheat gluten, nonfat dry milk). In this case, TTA becomes a more reliable way to control the extent of fermentation and acidity developed in preferments.
The higher the TTA, the stronger the fermentation flavors. A highly acidic preferment or dough (of high TTA) would exhibit a tart or sour taste.
TTA of liquid preferments and its relationship with pH
|Flour brew||TTA (mL)||pH|
|Water brew||TTA (mL)||pH|
Equipment needed for measuring TTA
- pH meter (end point indicator)
- Magnetic stirrer and stirring bar
- 150 mL erlenmeyer flask or plastic container
- Graduated cylinder
- Analytical scale
- Burette, ring stand, burette clamp
- 0.1 N Sodium hydroxide (NaOH)
- Distilled or reverse osmosis (RO) water
- pH standard buffers
Steps for TTA measurement
- Sample preparation (particle size reduction, homogenization)
- Weigh sample into flask or plastic container
- 15 g batter, sponge, dough, cake, etc.
- 20 g brew, poolish, sponge
- Add 100 mL RO or distilled water (non-finished product) or 150 mL water for baked goods
- Shake and blend water/product mixture until a relatively homogeneous suspension or solution is attained
- Add stirring bar
- Turn on stirring device to prevent particles from sinking
- Carefully insert pH electrode (equipment must have been properly calibrated)
- Record initial pH
- Titrate with 0.1 N NaOH
- Record volume of based used (mL) to reach end point (pH 6.6)
- Make sure pH remains stable (unchanged) at the final pH
- Cauvain, S.P. “Speciality Fermented Goods.” Technology of Breadmaking, 3rd edition, Springer International Publishing Switzerland, 2015, pp. 253–256.
- Tyl, C. and Sadler G.D. pH and Titratable Acidity. In: Nielsen S. (eds) Food Analysis. Food Science Text Series. Springer, Cham, 2017, pp, 389-406.