Abstract: Centella asiatica leaves were exposed to fermentation/oxidation for varying amounts of time: no fermentation (0 min), partial fermentation (120 min) and full fermentation (24 h). The chemical composition of the teas was determined and compared with commercial Camellia sinensis teas. The results of proximate analysis showed Centella asiatica herbal teas contained significantly higher amounts of protein, fat and ash than Camellia sinensis teas. Compared to Camellia sinensis teas, all Centella asiatica tea infusion extracts contained significantly more total free amino acids (24.87-54.44 mg l-glutamic acid equivalent g-1) but significantly less total free polysaccharides (24.33-31.52 mg glucose equivalent g-1) and were caffeine free. High thiamine, riboflavin, niacin and ascorbic acid contents were found in all Centella asiatica teas, but biotin was found only in fully fermented Centella asiatica tea (CAFF). Colour measurements demonstrated that Centella asiatica infusions generally had lowered a (greenness) and b (yellowness) values than Camellia sinensis teas. All infusions exhibited low turbidity levels (less than 10%), except for CAFF. However, the Centella asiatica teas exhibited significantly lower total phenolic (3.53-6.22 mg gallic acid equivalent g-1), total flavonoid (1.81-2.54 mg quercetin equivalent g-1) and total anthocyanin (0.99-1.49 mg catechin equivalent g-1) contents than Camellia sinensis teas and thus had lower antioxidant capacities (DPPH: 21.86-32.64 μm trolox equivalent g-1 and FRAP: 25.86-43.09 μm trolox equivalent g-1) than Camellia sinensis teas. Partially-fermented Centella asiatica (120 min) showed no significant change in antioxidant properties, but its total free polysaccharide content increased and it produced the darkest infusion.
Chew Shio Heong, Kaur , Bhupinder , Nurul Huda, Alias A. Karim and Ariffin Fazilah, 2011. Effect of Fermentation on the Composition of Centella asiatica Teas. American Journal of Food Technology, 6: 581-593.