Evaluation of nutritional and functional properties of economically important seaweeds

BACKGROUND: Seaweeds or marine macroalgae are plant-like organisms occurring abundantly (either attached to rocks in the oceans or to other hard substrata in coastal areas). Being nutritionally rich in proteins, vitamins, fatty acids (FAs), and elements such as iodine, iron, and calcium, they are potential functional food ingredients. Their nutritional profile changes with climate and species. Lack of knowledge regarding their nutritional richness makes them less popularly used in our daily diet. This study investigates the nutritional composition and functional properties of six seaweeds for their utilization in the daily human diet. METHODS: Nutritional profiles of six seaweeds (five collected from India and one from South Korea) were evaluated in this study. Their protein content was estimated on the basis of the nitrogen value (N × 6.25). Mineral content was determined using inductively coupled plasma atomic mass spectroscopy. Extraction of FAs methyl esters (FAMEs) was conducted followed by gas chromatography–mass spectrometry (GC–MS). Vitamins were determined using high-performance liquid chromatography. Differential scanning calorimetric (DSC) analysis, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) analysis of the dry seaweed samples were conducted. Functional properties [water-holding capacity (WHC), oil-holding capacity (OHC), and foaming capacity (FC)] of dried seaweed samples were determined using standard methods. RESULTS: The protein content of the studied seaweeds ranged from 7.940 to 36.190 g/100 g DW. Among the studied minerals, high Na content was observed in Enteromorpha compressa (i.e., 6.660 ± 0.013 mg/100 g) and high K in Kappaphycus alvarezii (5.590 ± 0.001 mg/100 g), respectively. FA profiling showed that Gracilaria sp. contained the highest saturated FAs. Maximum water-soluble vitamin, e.g., vitamin E (tocopherol) 0.643 mg/100 g contents, was seen in Caulerpa racemosa, whereas high ascorbic acid content was observed in E. compressa (2.975 mg/100 g). Riboflavin (B2) content of Ulva lactuca was 0.197 mg/100 g. FTIR, DSC, and TGA analyses were also conducted. WHC, OHC, and FC of the dried seaweeds revealed their applicability in food products. CONCLUSION: The nutritional and functional properties of the six seaweeds investigated suggest that they could be used for preparing functional food products. Promoting the use of seaweed as food and fodder could lead to enhancement of seaweed cultivation and harvesting, which in turn could also improve the socio-economic status of the coastal-dwellers.