Characterization of sea lettuce (Ulva lactuca) from Matara, Sri Lanka and development of nutribars as a functional food

Edible seaweed Ulva lactuca is a rich source of dietary fiber, protein, and minerals, but currently underutilized in Sri Lanka. In the present study, nutribars (composed of cereals and golden syrups) were developed incorporating dried U. lactuca powder (moisture content; 15.29 ± 0.03%, dry basis) at 5 and 10% (w/w) ratios. Seaweeds were manually collected in July, 2017 from Matara, Sri Lanka, cleaned, and oven-dried at 60 ̊C for 8 h. The proximate composition, crude ulvan content, swelling capacity, water holding capacity (WHC), and oil holding capacity (OHC) of powdered seaweed were evaluated. Further, crude protein content was estimated in 0 (control), 5 and 10% of seaweed incorporated nutribars. The crude protein content in dried U. lactuca was 20.16 ± 0.16%. The WHC of pulverized U. lactuca was 4.39 ± 0.07 g of water per g of seaweed powder, and OHC was 2.22 ± 0.27 g/g at room temperature (25 ̊C). Significantly highest (p<0.05) protein content (8.55 ± 0.38%) was found for 10% U. lactuca added nutribar while it was 7.54% (± 0.15) and 7.89% (± 0.03) respectively for 0% and 5% seaweed added nutribars. Moreover, the sensory evaluation results revealed that the nutribars incorporated with 5% U. lactuca (w/w) was shown almost similar sensory profile as the control except colour. However, 10% U. lactuca (w/w) added nutribars contained higher protein content than the control but rejected in overall acceptability.  Collectively, these results suggested that the under-utilized green seaweed U. lactuca can be incorporated at 5% (w/w) in nutribars.