Abstract
In this study, the mature leaves of Assam tea which were considered as waste were used as
substrate for solid state fermentation. The effects of solid state fermentation on phenolic
content and antioxidant capacities of Assam tea leaves using 4 different Trichoderma spp.
including Trichoderma harzianum CB-Pin-01, Trichoderma sp. NTY 211, Trichoderma
sp. PSUT 001 and Trichoderma sp. PSUT 002 were explored. The Assam tea leaves were
fermented in erlenmeyer flask by inoculum with the spore suspension and incubated at
30°C for 7 days, while a non-inoculum condition was served as unfermented sample. The
unfermented and fermented tea leaves were further extracted with different solvents
including water, 95% ethanol, 50% ethanol, 95% acetone and 50% acetone. The result
revealed that the color shade and intensity of fermented tea leaves extracts were changed
by types of fungi and solvents used. Evaluation of phenolic content, flavonoid content and
antioxidant capacities demonstrated that the highest phenolic (221.95±39.79 mg GAE/g
extract) and flavonoid (206.17±3.33 mg QE/g extract) contents were significantly
represented in unfermented tea extract prepared by 95% acetone. In addition, It also gave
the highest IC50 of 13.74 ± 0.22 and 5.76 ± 0.10 µg/ml which were assayed by DPPH and ABTS
radical scavenging activity, respectively, while the highest ferric reducing antioxidant power
(FRAP) value was represented in 50% acetone extract. On the other hand, fermentation
of Assam tea leaves dramatically decreased phenolic and flavonoid content as well as
antioxidant capacities. In all Trichoderma spp. tested, the isolate NTY 211 seemed to mostly
retain phenolic and flavonoid contents of 125.71 ± 3.61 mg GAE/g extract and 126.64 ±
3.14 mg QE/g extract, whereas IC50 values assayed by DPPH and ABTS radical scavenging
activity were equal to 27.98 ± 0.17 and 11.05 ± 0.11 µg/ml, respectively. This indicates
that solid state fermentation by Trichoderma spp. had an effect on reduction of phen
