The pH of kefir powder was determined by weighing 1 g of kefir powder that was added to 10 mL of distilled water and blended. To measure the pH of dough samples, 10 g of sourdough sample was added to 100 mL distilled water [26 (link)] and blended. Readings for pH were taken using a digital pH meter (Eutech pH 700 m, Thermo Fisher Scientific Inc., Auckland, New Zealand) with a glass electrode (Electrode ECFC7252101B, Thermo Fisher Scientific Inc., New Zealand). Before measurement, the pH meter was calibrated with buffers (Thermo Fisher Scientific Inc., New Zealand) at pHs 4.0 and 7.0. The pH measurements were performed in triplicate for each sample (at 0, 24, 48, 72 and 96 h).
The concentrations of D- and L-Lactic acid concentrations were determined using the Megazyme lactic acid kit K-DLATE01/14 (Megazyme, Auckland, New Zealand), following the manufacturer’s instructions. Total titratable acidity was determined using the AACC International Method 02-31.01 (AACC, 1999), where 10 mL of coconut water kefir sample and 10 g sample of coconut water kefir sourdough sample mixed with 100 mL of distilled water (at 0, 24, 48, 72 and 96 h) were titrated against 0.1 M NaOH, with a pH of 8.5.
The concentrations of D- and L-Lactic acid concentrations were determined using the Megazyme lactic acid kit K-DLATE01/14 (Megazyme, Auckland, New Zealand), following the manufacturer’s instructions. Total titratable acidity was determined using the AACC International Method 02-31.01 (AACC, 1999), where 10 mL of coconut water kefir sample and 10 g sample of coconut water kefir sourdough sample mixed with 100 mL of distilled water (at 0, 24, 48, 72 and 96 h) were titrated against 0.1 M NaOH, with a pH of 8.5.