The pericarp tissues of each sample fruit were finely sliced and ground using the Grindomix blender at low speed for 30 s. Three grams of ground material were then homogenised in 30 ml distilled water for 30 s, using a Polytron PT1600 (Bioblock Scientific, Illkirch, France). pH of the pericarp homogenate was mea-sured, using a digital pH meter (Titroline easy, Schott, Mainz, Germany) under continuous stirring. The titrat-able acidity, expressed as milliequivalents of acids per 100 g of pericarp, was measured by titration with 0.2 N NaOH solution to pH 8.1 using an automated titrimeter (Titroline easy, Schott).