Extraction of proteins from six seaweeds of south-east coast of India: Proximate composition and effect of process variables on protein solubilisation

Abstract

Seaweed resources have received huge interest as a dietary source of proteins. In this study, we investigated the effects of process variables such assolvent-to-solid ratio, duration, temperature and pH on solubilisation of proteins from Enteromorpha compressa with the aim of developing a process of seaweed protein extraction. Protein solubilisation was also assessed for five additional seaweeds viz, the brown seaweed Turbinaria conoides, the red seaweeds Kappaphycus alvarezii, Gracilaria edulis, and Hypnea valentiae) and the green seaweed Halimeda gracilis, using the optimum conditions derived for E. compressa. Protein content in the dried seaweed samples ranged from 3.05-11.29%. Based on the extent of protein solubilisation, the optimal conditions were found to be a duration of 30 min, pH of 9, temperature of 90˚C and dried seaweed-to-solvent ratio of 1:30. Under these conditions, 19.90% of proteins from E. compressa were solubilised. Under the same process conditions, protein solubilisation from T. conoides, K. alverzii, H. gracilis, H. valentiae and G. edulis was 27.39, 30.88, 45.57, 19.68 and 40.32%, respectively. The investigation condluded thatprotein extraction from seaweeds is highly challenging and needs further research for improved recovery. Keywords: Alkali solubilisation, Process variables, Protein extraction, Seaweed protein