ABSTRACT
This study aimed to investigate the effects of aquaculture and the optimum conditions for drying duckweed plants to maintain the highest nutritional value and bioactive substances. Protein quantification was used to screen duckweed plants subjected to the 14 treatments under aquaculture conditions. Proximate analysis of three aquaculture conditions showed the highest quantification of protein. Moreover, these samples were analyzed for total phenolics, flavonoids, and chlorophylls. The optimal drying conditions for duckweed plants with the highest protein content were determined using a factorial design with three temperature and time parameters. The results showed that the duckweed under aquaculture conditions in an outdoor cement pond with hydroponic electrical conductivity (EC) of 0.5 mS/cm contained the highest protein at 41.81 ± 3.40%. Moreover, proximate analysis of this sample showed fat, fiber, moisture, ash, and carbohydrate contents of 1.99 ± 0.08%, 4.46 ± 0.71%, 3.29 ± 0.17%, 22.06 ± 0.07% and 14.12 ± 1.63%, respectively. In addition, the optimum drying conditions for this sample were 50 °C and a drying time of 6 h. Under optimum drying conditions, this sample showed total phenolics, flavonoids, and chlorophylls contents of 55.28 ± 1.35 (µg GAE/g dry weight), 159.84 ± 6.65 (µg catechin equivalent [QE]/g dry weight) and 22.91 ± 0.15 (mg/g dry weight), respectively. In conclusion, the dried duckweed under aquaculture conditions in an outdoor cement pond with hydroponic EC 0.5 mS/cm contained the highest contents of proteins, total phenolics, total flavonoids, and total chlorophyll, which could be used as functional ingredients in health food products.
ABSTRACT
BACKGROUND: Yanang (Tiliacora triandra) has been known as vegetable and herbal in northeast Thailand and Lao People's Democratic Republic. Extracts from Yanang leaves contain high amounts of polyphenol constituents possessing antioxidant activity. MATERIALS AND METHODS: This work investigated bioactive compounds of Yanang extracts prepared by infusion with water, ethanol and acetone. Furthermore, this paper reports the design of the experimental method for optimization of Yanang encapsulation using three independent variables: the ratio of core material (Yanang), to wall material (gum Arabic), gum Arabic concentration and inlet temperature of spray drying on bioactive compounds stability. The stability of bioactive compounds was evaluated using phenolic compounds, total antioxidant, carotenoids and chlorophyll. RESULTS: The study of the bioactivity of Yanang extracts found that extraction with water was the appropriate application. The study of Yanang encapsulation demonstrated that gum Arabic, as coating agents, protected bioactive compounds of Yanang. Optimized condition for the encapsulation was at the ratio of core to wall {1:4}, in gum Arabic concentration 10% (w/v), and inlet temperature at 160â¯C. The results show that the bioactive compounds were mainly affected by the ratio of core to wall material. Besides, moisture content and particle size of encapsulation depend on inlet temperature of spray drying, and gum Arabic concentration, respectively. This optimization reveals that the encapsulation process did not lose the bioactive compounds. CONCLUSION: Yanang extract with water was the main phenolic compound and showed high antioxidant activities. This study demonstrates the potentials of using spray drying process and optimization for the encapsulation of herbal products.
