ALBERT

Description: The value of macroalgae in a healthy human diet is becoming increasingly recognized and supported throughout Europe. Macroalgae provide a rich source of vitamins, minerals, proteins, fatty acids, and antioxidants that also support the functionality of macroalgae in other industries, including cosmeceuticals, pharmaceuticals, and more recently, packaging. Sustainable aquaculture of macroalgae will be necessary to supply the increasing demand for macroalgae as a functional material, considering that natural harvests are limited and cannot keep up with demand. Different methods can be used to cultivate macroalgae, including flow-through systems or recirculating aquaculture systems (RAS) with natural or artificial seawater. The latter provides strict control over the growth conditions and water quality in order to provide a high quality and traceable product. Additionally, environmental conditions such as salinity, temperature, and light can be modified to optimize the concentration of functional ingredients in macroalgae. While most research efforts have focused on seasonal and geographic trends in concentrations of functional ingredients in wild macroalgae, there is less information available on optimizing these functional ingredients in aquaculture. Therefore, we performed controlled experiments to optimize the activity of antioxidants in Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N.Norris et Fredericq comb. nov. (formerly Gracilaria vermiculophylla) grown in RAS with artificial seawater and commercial fertilizer. We show that the free radical scavenging activity could be increased by 13% via high salinity, and up to 34% by increasing the light intensity, but not daily light dose, for a period of 7 days. We also monitored growth rates and the maximum quantum yield of photosystem II (Fv/Fm) and show that the conditions for optimizing antioxidant activity are not optimal for growth or photosynthesis. We therefore suggest an optimization period of 4–7 days exposure to high light on a 6:18 hour light:dark cycle prior to harvesting in order to increase antioxidant activity.

Description: Single-use food packaging contributes towards almost one-third of the global plastic waste. In an attempt to minimize environmental impacts, sustainable alternatives need to be developed. Seaweed is a renewable resource that can be utilized for packaging development for plastic replacement. Gracilaria is one of the most widely-cultivated algae, used in food and pharmaceutical industries as a valuable source of agar. Studies have succeeded in developing biopolymer plastics from Gracilaria containing high levels of antioxidants. Antioxidant properties are essential in biopackaging as they are beneficial to packaged food by limiting lipid oxidation, which is one the main causes of the food spoilage. This study focuses on the cultivation of Gracilaria vermiculophylla and optimizing its antioxidant properties for further use as an edible film for food packaging. Antioxidant compounds are synthesized in seaweeds as a response to oxidative stress that often occurs due to harsh environmental fluctuations. Therefore, antioxidant activity of the seaweed can be modified through exposure to different stress conditions. Three consecutive experiments were conducted in this study to better understanding on how different levels of light irradiance, differences in light : dark cycles, exposure to UVA radiation, hypersalinity, desiccation and the duration of exposure can affect the antioxidant profile of Gracilaria vermiculophylla. High light intensity increased the antioxidant levels of G. vermiculophylla, reaching a maximum of 33.45%. Moreover, the combination of the high light irradiances and UVA enhanced the antioxidant activity and had a positive survival effect on G. vermiculophylla. The study showed that increased antioxidant activity could be achieved after 3 days of exposure to different cultivating conditions. These findings may be beneficial to industrial scale seaweed cultivation, where favorable antioxidant levels could be reached shortly prior to harvesting.