# Analysis of Seaweeds from South West England as a Biorefinery Feedstock
## 3 Results and Discussion
### Pigments  
In 2016, the global pigment and dyes market was estimated to be valued at $30.42 billion [21], and is expected to see significant growth in demand in the coming years. Whilst global omega-3 and omega-6 PUFA supplies are intrinsically linked with marine algae production, the pigment and dyes market is not as reliant on marine sources, and establishing seaweed-derived materials is more challenging. Nevertheless, seaweed pigments have found uses due to the fact of their antimicrobial properties [22], as well as uses in dyes, additives, health supplements, antibiotics, bioelectronics and antioxidants. The pigment content of each seaweed species was identified using HPLC. The primary pigments are given in Table 3. Levels of pigmentation varied both within taxon and among species. The lowest overall pigment content was seen in _Alnfeltiopsis devoniensis_ with just 37 \(\upmu\)g pigment/g dry biomass whilst _Punctaria latifolia_ had the highest content at 1319 \(\upmu\)g/g. Fucoxanthin, the xanthophyll responsible for the brown colouring of Phaeophyta, has been shown to have promising therapeutic uses in cancer and obesity treatments [23; 24], as well as antibacterial properties [22] and could be beneficial in fertilisers, as it can help to reduce crop diseases. Unsurprisingly, whilst low levels of this pigment were observed in all the seaweeds analysed, only the browns contained it at concentrations that could be useful for industrial extraction, ranging from 340.4 \(\upmu\)g/g in _Punctaria latifolia_ to just over half this in _Fucus serratus_ at 131.8 \(\upmu\)g/g. Product colour can have a huge impact on consumer perception, but concerns over the safety of synthetic colour additives and the increase in industrial safety requirements is leading the food and drink industries to increasingly seek natural colour alternatives [25]. Seaweed pigments range in colour from blue-greens (chlorophylls) to yellows (xanthophylls) and orange-reds (carotenes), and have a similar level of stability relative to their synthetic counterparts making them ideal as food colourings [26]. Chlorophyll (chl) is already approved and registered as a food additive (E140) and is used to colour various foods and beverages green [27] and has also been shown to have potential uses within cosmetics as deodorants and dentifrices due to the fact of its odour reducing properties [28]. As expected, both the levels and types of chlorophyll varied across the seaweed species tested. Both the green seaweeds had chl-b and chl-a at an approximate ratio of 1:1.5 (_Spongomorpha aeruginosa_) and 1:1.4 (_Ulva lactuca_). The red seaweeds generally contained predominantly chl-a, with very low levels (less than 10% of the chlorophyll pigment pool) of chl-c and/or chl-b. The exception was _Palmaria palmata_ which contained chl-a only. The brown seaweeds all generally contained chl-c at levels of 12-22% than that of chl-a. The exceptions to this were _Fucus serratus_ which had an approximately 50:50 ratio of chl-c:chl-a, and _Gastroclonium ovatum_ whose chl-c accounted for just 0.5% of its total chlorophyll pigmentation. The carotenoids \(\alpha\) and \(\beta\) caroten are converted to vitamin A in the human body [29] and along with the xanthophylls lutein, zeaxanthin and violaxanthin, play a crucial role in maintaining eye health as well as reacting with free radicals to reduce oxidative stress and lipid peroxidation [24; 30]. _Punctaria latifolia_ contained the highest level of carotenoids at 46.8 \(\upmu\)g/g, _Palmaria palmata_ had the highest levels of lutein at 56.4 \(\upmu\)g/g and _Gastroclonium ovatum_ the highest levels of zeaxanthin at 11.8 \(\upmu\)g/g. Violaxanthin was abundant in all the brown seaweeds with _Punctaria latifolia_ containing 106.3 \(\upmu\)g/g of this orange pigment.