Cinnamomum porrectum herbal tea production and its functional properties influenced by odor types of leaves and blanching process

Abstract

Cinnamumum porrectum (Roxb.) Kosterm. with Thai name "Thep tharo", is an aromatic plant grown in Southern of Thailand. Nowadays, this plant is rapidly decrease because the wood and root were used to produce essential oils and handicraft products, so deforestation was occurred. From this problem, the Technology Research Centre of Forestry sector, Songkhla gave the preservative idea for increase the plantation. According to the lowest utilization of leaves since they provided a small amount of essential oils. However, the leaves are still interesting due to their aroma from the chemical constituencies in volatile oils. They were classified as root beer odor, cajuput odor, lemongrass with orange odor and flower with spice odor. The Technology Research Centre of Forestry Sector in Songkhla encouraged the local entrepreneurs to produce Theptharo leaves tea however, there are some problem such as lack of data about herbal tea production and scientific data especially the functional properties and the safety guarantee. So, the main point of this research was to study the process of Thep tharo herbal tea production starting with root beer odor and used the selected process for all 4 odors of Theptharo leaves. The nutritional composition, physiochemical properties, phenolic composition, total extractable phenolic content (TPC), total extractable flavonoid content (TFC), antioxidant activities, nitric oxide inhibition, the cytotoxicity on HEK293 and anti-colon cancer (HT-29 and Caco-2) of Theptharo tea extracts were analyzed. The effect of drying temperature and steeping time on C. porrectum herbal tea were studied (temperature; air-drying at 28-30 °C, hot air-drying at 50, 60, 70 and 100 °C compared with freeze-drying and steeping time; 5, 10, 20 and 30 min). The result indicated that drying at 60 °C provided the highest TPC and TFC when compared with 70 °C, 50 °C and 100 °C, respectively. The steeping time more than 10 min not effect on TPC and TFC (p>0.05). So, this drying temperature was selected to next study. The pre-treatment process was applied to the leaves due to (1) long drying time decreased antioxidant activities (2) the stalk of leaves gave the viscosity like gum in herbal tea infusion (3) cutting process induced enzyme activity. The result indicated that blanching can decrease the peroxidase (POD) and polyphenoloxidase (PPO) more than steaming when compared with the same time for 60 s. The TPC, TFC, DPPH and ABTS were significantly increased. Blanching not only increase the extractability but also decrease chlorophylls loss during drying process, keep the green color (-a*) and can eliminate safrole more than 89%. Blanching for 60 s was selected and applied into 4 odors of leaves compared with un-blanched herbal tea. The results indicated that the phenolic composition of all samples provided the 8 main compounds including pyrogallol, gallic acid, protocatechuic acid, catechin, caffeic acid, syringic acid, p-coumaric acid and rutin. Various odor types of leaves provided the same types of phenolics but different in contents. The highest of TPC was found in flower with spice odor. The cajuput odor provided the highest of DPPH, ABTS and FRAP. The root beer and lemongrass with orange odor gave a higher content of TPC, TFC, DPPH and FRAP in blanched sample when compared with un-blanched sample. In the cell culture studies, all herbal teas extract at concentration lower than 50 ug/ml had no toxicity on RAW264.7 cells (percentage of cell viability more than 80). The flower with spice odor (both blanched and un-blanched) and lemongrass with orange (blanched) provided a higher ability on NO inhibition more than positive control L-No-nitroarginine (L-NA) (IC50-30.21±1.48 μg/ml). In un-blanched group, the lemongrass with orange odor showed the lowest toxicity (CC50-922.76±50.11 μg/ml) on HEK293 cells. The cytotoxicity on HEK293 was decrease in blanched group. In un-blanched group, the cajuput odor provided the highest anti-colon cancer on HT- 29 (CC50-438.19±30.36 μg/ml) while the flower with spice odor and lemongrass with orange odor showed a higher cytotoxicity on Caco-2 cells. The conclusion from this study suggested that the root beer odor should be blanched before making herbal tea. The cajuput odor provided the highest of antioxidant activities and gave the highest anti-colon cancer on HT-29 cells. The lemongrass with orange odor and flower with spice odor provided a high ability on NO inhibition, higher toxicity on both colon cancer cells.