An in vitro investigation of the initial pH and titratable acidity of a selection of fruit smoothies.

Four commercially-available fruit smoothie drinks were assessed for both initial/baseline pH and titratable acidity. A commercially-available smooth orange juice drink was used as a positive control. Baseline pH and titratable acidity were measured by titrating each fruit smoothie with 0.5 mL increments of 1M sodium hydroxide (NaOH), and measuring the pH following the addition of each increment, until pH 7 and pH 10 were reached. Each of the fruit smoothies investigated demonstrated a low baseline pH and had relatively high titratable acidity. Owing to both their low pH and high titratable acidity, it would be advisable to limit the consumption of such fruit smoothies to meal times. CLINICAL RELEVANCE: Fruit smoothies, which are made from pure fruit blended with 100% fruit juice, are a relatively new addition to the soft drinks market. It is recommended that they be consumed through a straw, similar to the advice given for other acidic soft drinks.