Mangosteen fruits imported from Malaysia were purchased from a local supermarket in Singapore. The fruits were washed, pulps extracted manually and the parts of pulp which mainly consisted of seeds were excluded. The remaining fruit pulp was blended to obtain mangosteen juice (0.6 litre), which was then used for triplicate laboratory-scale fermentations. Blended mangosteen juice had an initial °Brix of 16.07% and initial pH of 3.25, which was then adjusted to pH 3.50 with 1M NaOH. The adjusted mangosteen juice was centrifuged at 16,873 × g (Beckman Centrifuge, Palo Alto, CA, USA) for 20 min at 4°C. After centrifugation, the juice was filter-sterilised through 0.65 μm and 0.45 μm polyethersulfone filter membranes (Sartorius Stedium Biotech, Goettingen, Germany).