Optimization of an Air-Drying Process to Obtain a Dehydrated Naranjita (Citrus MitisB.) Pomace Product With High Bioactive Compounds and Antioxidant Capacity

Polyphenols and Antioxidant Activity of Thunbergia laurifolia Infused Tea under Drying Conditions

Thunbergia laurifolia leaf is used in Thai herbal medicine to moderate alcohol, food poisoning, and other health-related diseases mainly due to its overwhelming phytochemical compounds which exert several biological functions such as antioxidant, and anti-inflammatory properties, among others. This study investigated the potential effects of hot air-drying conditions (TL-D80°C, TL-D90°C, and TL -D100°C) of T. laurifolia tea leaves on phenolic compounds, total flavonoid content (TFC), total phenolic content (TPC), and antioxidant activities (AOA) of the infused teas. The results show that an increase in drying temperature significantly $\left(p<0.05\right)$ improved TPC (709.7 ± 1.36–744.8 ± 5.79 mg GAE/) and TFC (198.98 ± 7.59–207.16 ± 4.10 mg RE/L) of infused teas. TL-D80°C (69.9 ± 0.95%) and TL-D90°C (69.3 ± 0.7%) infused teas showed significantly $\left(p<0.05\right)$ higher DPPH inhibitory effect compared to TL-D100°C. Treatment had no effects $\left(p>0.05\right)$ on ABTS.+ scavenging activity. The phenolic compounds detected in infused teas were rosmarinic acid, caffeic acid, gallic acid, catechin, rutin, and quercetin. Regarding, the cumulative phenolic compounds TL-D100°C infused teas were significantly higher $\left(p<0.05\right)$ compared to TL-D90°C and TL-D80°C. The results suggest that drying conditions (i.e., TL-D100°C within 30 min) could be used to achieve appropriate moisture content of T. laurifolia tea leaves without compromising the phytochemical compositions and antioxidant potentials of the resulting infused teas.

Analysis by UPLC-DAD-ESI-MS of Phenolic Compounds and HPLC-DAD-Based Determination of Carotenoids in Noni ( Morinda citrifolia L.) Bagasse

Noni bagasse is usually wasted after the noni juice extraction process. The purpose of this study was to investigate the phytochemical composition of noni bagasse (with and without seeds) obtained after a 1 week period of a short-term juice drip-extraction process from over-ripe noni fruit. Totals of free phenolics, flavonoids, condensed tannins, carotenoids, and most of the minerals were higher in bagasse without seeds (NSB) than in bagasse with seeds (WSB), whereas bound phenolics and total and insoluble dietary fiber were higher in WSB than in NSB. β-Carotene and lutein, quantified by HPLC-DAD, were higher in both bagasse than in juice. A total of 16 phenolic compounds and 2 iridoids were determined by UPLC-DAD-ESI-MS. Among them, procyanidin B-type dimer, caffeoylquinic-acid-hexoside, and quercetin-hexose-deoxyhexose have not been previously reported in noni bagasse, noni juice, or noni fruit. Isorhamnetin-3- O-rutinoside was the most abundant compound in both bagasses. In conclusion, both bagasses are potential sources of phytochemical compounds for the food and pharmaceutical industries.