An Investigation of the Bioactivity of Irish Seaweeds and Potential Applications as Nutraceuticals.

The primary goals of this research were to; identify the bioactivity of a range of edible Irish seaweeds, to examine the current technological procedures currently applied with respect to seaweed processing and in light of this information, to examine the potential of incorporating seaweeds into traditional food products in order to enhance their nutraceutical properties. Currently most Irish seaweeds are washed, dried and packaged, with little done to increase consumer appeal or interest and dried seaweed may appear inaccessible and unfamiliar to consumers. Seaweeds possess an excellent nutritional quality, such as high fibre and phytochemical content, low cholesterol and low glycaemic index (G.I.) and therefore have the potential for classification as functional foods. The first stage of the research was to assess the bioactivity of a range of edible Irish seaweeds, including brown, red and green species, which were available throughout the year (Laminaria digitata, Laminaria saccharina, Himanthalia elongata, Palmaria palmata, Chondrus crispus and Enteromorpha spirulina.) Brown seaweed, H. elongata, contained the highest levels of bioactivity in terms of antioxidants and antimicrobials, and was therefore the primary seaweed focused on for the remainder of the research. As seaweeds require some processing to make them edible and palatable, optimal processing treatment was established by investigating the effect of a range of common thermal processing methods such as; drying, boiling, steaming and microwaving on the phytochemical content. It was found that a drying pre-treatment before hydrothermal processing reduced the time required for processing (15 min less) and subsequent phytochemical losses (9% reduction). Atmospheric drying is the most common preservation method in Ireland for seaweed yet there is little effort made to optimise the process in order to capitalise on the nutritional content. With these facts in mind, iii drying kinetics under controlled conditions were investigated and mathematically modelled. In terms of phytochemical content, drying was optimised at 40 °C for 2 hours. Under these conditions, reducing the moisture content by 50% caused an increase in phenolic content up to 41%. Rehydration kinetics were also investigated using Response Surface Methodology (RSM) and phytochemical content was maximised by rehydrating at 80.5 °C for 20.4 min. The processed seaweeds were successfully incorporated into commonly consumed convenience products (breadsticks and beef-patties) in order to increase phytochemical and fibre levels and the products were sensorially acceptable as determined by a sensory panel. The overall results of this study indicated that reductions in bioactivity due to application of the current technological procedures could be minimised under controlled conditions. The seaweeds processed with optimal phytochemical levels were sucessfully incorporated into convenience products with enhanced functionality. Such foods would provide innovative new products which could support the Irish seaweed industry while promoting seaweed to a market who otherwise would not consume such a food