https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33067 Sargassum vestitum, Sargassum linearifolium, Phyllospora comosa, Padina sp., Hormosira banksii and Sargassum podocanthum, were investigated for the chemical profile and antioxidant activity. The results showed that the extracts H. banksii, S. vestitum and Padina sp. indicated the significantly higher total phenolic compound (TPC) and antioxidant activities (ABTS, DPPH and FRAP) compared to the other species (P < 0.05) and comparable to positive controls: butylated hydroxytoluene, ascorbic acid and alpha‐tocopherol at the concentrations (0.06–1 mg mL−1). Fucoxanthin was also found in six species and isolated for evaluating antioxidant activity. In addition, the phenolic compounds were mainly responsible for antioxidant activity of the extracts, while fucoxanthin showed quite high antioxidant activity. It is suggested that S. vestitum, H. banksii and Padina sp. have the potent for extracting bioactive components and further applications in food and pharmaceutical industries.]]> Fri 24 Aug 2018 13:45:12 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33071 Hormosira banksii is a rich source of polyphenols, which can be utilized in the food or pharmaceutical industries. This study aimed to determine the impact of six drying methods on properties of the alga H. banksii. Our data revealed that drying conditions significantly affected recovery yield, residual moisture, extraction yield, total phenolic content (TPC) as well as antioxidant capacity of H. banksii (P < 0.05). Optimal conditions for oven, vacuum and de‐humidification were 40, 50 and 50C, respectively, and microwave power is 840 W. Under optimal conditions, H. banksii prepared by freeze, de‐humidification and vacuum had significantly higher levels of TPC, total flavonoid content (TFC) and proanthocyanidins as well as possessing stronger antioxidant capacity in comparison with those prepared by sun, microwave and oven drying methods. As freeze drying is costly and time‐consuming, de‐humidification (50C, air in and out of 11.1 and 15.4%) and vacuum (50C, 10 psi) were recommended for drying H. banksii. Practical Applications: Algae possess various antioxidants with potential benefits for health. Drying is considered as a method for preserving materials, transport with low costs and especially first step for extraction, isolation and purification of active compounds. Thus, it is important to investigate the effects of drying conditions on the properties of the dried alga H. banksii. From the findings, the different drying conditions significantly affected the phytochemical profile and antioxidant activity of the dried alga and the optimal drying conditions could be applied for preparation of dried H. banksii for further processing (extraction, fractionation and isolation of bioactive compounds) as well as potential industrial applications (as a reference for drying H. banksii and other algae).]]> Fri 24 Aug 2018 13:45:06 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33068 Hormosira banksii for total phenolic content (TPC) and antioxidant activities including total antioxidant capacity (ABTS), DPPH free radical scavenging capacity (DPPH) and ferric reducing antioxidant power (FRAP) using response surface methodology (RSM). Box–Behnken design was employed to assess the effect of ultrasonic temperature, time and power on the TPC and antioxidant activities of the extracts. The results showed that RSM was an accurate and reliable method in predicting TPC and antioxidant activities (ABTS, DPPH and FRAP) of the extracts with R² values of 0.97, 0.96, 0.92 and 0.94, respectively. The ultrasonic temperature and time had the significant impact on TPC and antioxidant capacities. The optimal UAE conditions for the maximal values of TPC and antioxidant activities were of 30 °C, 60 min and power 60%, or 150 W. The values of TPC and antioxidant activities (ABTS, DPPH, FRAP) achieved under these parameters were 23.12 (mg GAE g⁻¹), 85.64 (mg TE g⁻¹), 47.24 (mg TE g⁻¹) and 12.56 (mg TE g⁻¹), respectively. UAE was found to be more efficient in comparison to conventional extraction, with shorter time for extraction and higher of TPC level and antioxidant activities. Therefore, ultrasonic-assisted extraction using RSM is effective for extraction and further isolation and purification of phenolic compounds from H. banksii. In addition, this alga could be a potential rich source of natural antioxidants applied in food and pharmaceutical fields.]]> Fri 24 Aug 2018 13:44:59 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33066 Fri 24 Aug 2018 13:44:52 AEST ]]>