EAWEEDS are marketed as “functional foods” or “nutraceuticals” due to their highly biochemical ingredients, and they are vital as food supplement in order to relinquish physiological condition and resist diseases. In the present study, the biochemical compositions of the seaweeds Caulerpa racemose, Digenea simplex, Sargassum polycystum and Cystoseria myrica were studied. The total protein, carbohydrate, lipid, fatty acids, amino acid, Minerals and dietary fibers were assessed. The highest content of protein found in D. simplex, while C. racemosa has the highest lipid contains. The highest concentration of carbohydrates and dietary fibers was detected in S. polycystum and C. myrica. C. myrica branded by high concentration of vital amino acids. In This investigation, we illustrated the consumption of seaweeds as appreciated nutritional food and therapeutic products due to their chemical composition, as well as partial replacement of conservative dietary protein sources.
Seaweeds are used since ancient times as food (Alexandre et al., 2017), fodder and fertilizer and as supply of healthful medication (Rupapara, 2017). They need gained importance as meditative sources due to their high healing, antimicrobial and antioxidant activities (Jiao et al., 2010). (Gade et al. 2013 and Ismail 2017) illustrated the vital role of seaweeds for human and animal health and consumed as daily diets in orient countries
Seaweeds are referred to appreciate sources of protein, elements, dietary fibers, vitamins, essential amino acids and they contain frequent polysaccharides, including alginate, cellulose and laminarin (Lyu et al., 2016) Moreover, seaweeds also contain potential bioactive compounds which exhibit medication, antiviral and antifungal properties (Marinho-Soriano et al., 2006). Ortiz et al., 2006 inveterate that the species, maturity, environmental growth conditions and seasonal period Influenced on the nutrient compositions of seaweeds.
Owing to the accumulative world population, the anxiety for food and energy are levitation the necessity for numerous, sustainable sources for food commodities (Janssen et al., 2018).
Seaweeds display excessive disparity within the nutrient contents that are related with numerous environmental factors as water temperature, light and nutrients (Paiva et al. 2017and Parker 1998). Most of the conservational restrictions diverge conferring to season and the variations in ecological conditions will stimulate or inhibit the biosynthesis of many nutrients (Hernández et al., 1995 and Manivannan et al., 2009). They are the most nutritious and rich in vitamins and minerals than the other food. The nourishing assets of seaweeds are poorly known and normally are assessed from the chemical composition (Ismail, 2017).
The most necessary biochemical components of algae are protein, carbohydrates and Lipids. Limited studies were done on fatty acids of microalgae and seaweeds. Macroalgae biomasses can accumulation large amounts of oil which can be demoralized for the assembly of biodiesel (John & Anisha, 2011). The species of algae play a vital role on alteration the protein content (Ratana-arporn & Chirapart, 2006).
Some evidences counsel that fatty acids and sterol composition could also be helpful for taxonomic purposes (El-Shafay, 2014 and Herbreteau et al., 1997). Accumulation of olefinic fatty acids was observed in Rhodophyta, principally arachidonic and eicosapentaenoic acids. Alternative luxuriant fatty acids during this category are palmitic and oleic acids. The amino acids composition pronounced variations were discovered in protein and amino acids between different algal groups (MacArtain et al., 2007 and Qasim, 1991).
Seaweed has lots of essential nutrients, fundamentally trace elements and a number of other bioactive substances. That explains why nowadays seaweeds are considered as the food supplement for twenty-one century as supply for first proteins, lipids, polysaccharides, mineral, vitamins and enzymes.The intention of this work is to investigate the biochemical composition (in protein, carbohydrate, lipid, fatty acids and amino acids) in Caulerpa racemosa, Digenea simplex, Sargassum polycystum and Cystoseria myrica.
Materials and methods
Four marine algal species were picked from Hurghada Red Sea coastal, Egypt throughout March 2017. These species classified into three categories chlorophyta species (Caulerpa racemosa), Phaeophyta species (Sargassum polycystum and Cystoseria myrica) and Rhodophyta species (Digenea simplex).
All samples were delivered to laboratory in plastic bags containing sea water to forestall evaporation. Epiphytic and potential contaminants were rinsed with sea and distilled water. The seaweeds were dried in room temperature air and kept in plastic bags for biochemical analysis.
Lowry method (Lowry et al., 1951) was employed to evaluate Seaweeds total protein. The dry seaweeds were extracted by Tris HCL buffer (0.1 M pH7.5) overnight at 4 °C with stirring. The supernatant total protein was monitored photometrically at 750 nm using a standard bovine serum albumin (BSA). The Amino acids profile of the extract was determined using amino acids analyzer.
Dubois et al., 1956 was employed the Phenol-Sulphuric acid method to evaluate seaweeds total carbohydrate. Folch et al. (1957) used chloroform-methanol mixture to assessed Lipid content.
Dietary fiber analysis
Dietary fiber was evaluated by the indigestible fraction method (Goni et al., 2009), in which the 4 dried edible seaweeds were subjected to several enzymatic treatments (pepsin, pancreatin, α-amylase, and amylo-glucosidase), dialysis to remove the digestible components of the sample and separate soluble and insoluble dietary fiber.
The elements contents analyses
The element contents were analyzed photometry (AAS) for Ca, Mg, K and Na, gravimetric method for P (Kolthoff et al., 1969). A toxic lead was conducted according to the methods of Evan (1978) and Suddendorf et al. (1981).
Lepage and Roy (1984) were modified by Pereira et al. (2012) to estimate fatty acid methyl esters (FAME). Determination of the total amino acids was performed by Walker et al., 1996 protocol at the National Center of Radiation Research and Technology, Cairo, Egypt.
The biochemical components (proteins, carbohydrates, lipids and Mineral composition) were obtained as the mean of three replicates ± SE (standard errors). The mean values of control and treated species were implemented by Duncan’s multiple range test (DMRT) at the significant level of p < 0.05 using SPSS (version 21.0)
The most vital organic chemistry constituents of algae are protein, carbohydrate and lipid (Hannan et al., 2013 and Chew et al., 2017). A carbohydrate is that the main molecule symptoms that influence on different physiological response in regulated genes in photosynthesis, metabolism and self-protective retorts. There are alterations in the accumulation and distribution of carbohydrates among the two studied algae. There are variances in the accumulation and distribution of carbohydrates within the four studied macroalgae. In the current investigation, the data of carbohydrates accumulation exposed three situation of the accumulation of carbohydrate were recorded in four species as the following:
- Decrease in C. racemos and about the same content in D. simplex 42.40%
- Increased progressively in S. polycystum
- Moderate in C. myrica about 78.7 %.
Environmental factors and the method used to extraction (Peinado et al., 2014) the most vital role to alteration between species. Dhargalkar et al. (1980) and Sobha et al. (2001) illustrated that maximum value of carbohydrate accumulation in Rhodophycean members higher than in Phaeophycean and Chlorophycean members. In the current investigation, the contrastingly Phaeophycean members showed high carbohydrate content than Rhodophycean and Chlorophycean members. The higher accumulation of carbohydrate in phaeophycean might be due to higher phycocolloid content in their cell walls (Dhargalkar et al., 1980).
The all picture of protein in the four algae species revealed that the criteria of protein differ greatly among the different species of algae used (type of algae is the mainly factor on these fractions) for example:
- Moderate for green algae (17.81% of dry weight).
- Low for brown seaweeds (5.85& 10.35 % dry weight).
- High for red seaweeds (maximum 21.14 % dry weight)
The association among all algal species was nonsignificant (one-way ANOVA, p < 0.05). These variances might be predictable as dissimilarities in the protein content of seaweeds can be accredited to species variances and seasonal effects (Fleurence et al., 2018).
The total lipid contents within the studied seaweed species were relatively low (Fig. 1), the highest value was found in C. racemose 4.45 %, and however the lowest value was recorded in S. polycystum. Typically, seaweeds don’t seem to be good source of lipid (Ratana-arporn & Chirapart, 2006), and the total lipid content was perpetually found less than 4% (Herbreteau et al., 1997). These results are supported by the conclusions of (Shanmugam & Palpandi, 2008) in Sargassum wightii (0.45 %), in Caulerpa racemosa (7.56) and in brown alga jania (0.9 %). The dissimilarities might are because of factors like climate and geography of development of the seaweed (Herbreteau et al., 1997).
These results refer that the brown algae rich in dietary fibers when compared with other seaweeds. Conferring to the standard daily amount of dietary fiber (25 g per day) Susan and Robin, 2002. Seaweeds can deliver up to 12.5% of a person’s every day. This is relatively large amount when compared with other terrestrial foods.
Ion quotient Ca+Na/ Mg+K this molar ratio was calculated (Table I) to be 0.20, 0.99, 0.99 and 0.79 for D. simplex, S. polycystum, C. racemosa and C. myrica, respectively. The ion quotient usually diverges between 2.5 and 4.0 in human body (El-Said & El-Sikaily, 2013). These results infer that exhausting seaweed species in foods can reduction this range in human body and lessen related diseases such as hypertension, and heart disease.
Seaweeds are currently deliberated to be a promising source of fatty acids (FA). However, FA content and their composition can vary greatly depending on species and environmental conditions. As detected from table II, fatty acids were the predominant in types present in the all studied species. Species D. simplex & S. polycystum contain the highest percentage of total fatty acids, while, Brown seaweeds contain the lowest content of total fatty acids. This result corresponds with (Shanmugam & Palpandi, 2008) who found that the saturated fatty acids constituted 70.01% of the total fatty acids. As detected from table II, the unsaturated fatty acids present by nearly low concentration in the four studied species (Ishakani, 2017). In the recent search species C. racemosa was branded by the highest amount of polyunsaturated fatty acids among the premeditated algae, and it characterized by the present of Linoleic (ω6) (C18:2). This discrepancy could be due to various factors, allied result has been obtained (Colombo et al., 2006). Conferring to Nelson et al. (2002), total macroalgae lipid content accumulated during winter and spring and deteriorated in summer. Temperature considered the most important environmental factors that influenced on fatty acids cell membranes (Peng et al., 2015) wherever at low temperatures Fatty acids contents escalation and algae from cold waters are frequently richer in PUFA in contrast to those from warm waters.
The nutritive assessment of food can be determined by the content, proportion and availability of its amino acids, particularly for assessment of a new protein resource (Gressler et al., 2009). The four species contained large amount of aspartic and glutamic acids, which are responsible for the special flavor and taste. Related results have been obtained in prior studies (Gressler et al., 2010 and Wong &Cheung, 2000)
The studied species featured distinctive high concentrations of essential amino acids; whereas nonessential amino acids present with low concentration within the all studied species. These results coincide with (Ratana-arporn &Chirapart, 2006) who rumored that C. lentillifera and U. reticulata proteins were of prime quality as a result of the essential amino acids described virtually 40% of total amino acids. Geographic factors seemed to have a significant effect on the amino acid composition of macro-algae.
Hence, results of the current study determine that seaweeds are a prospective health food in human diets and in the food industry as a source of constituents with high nutritional worth. Seaweeds can provide a dietary alternate owing to its nutritional assessment and its commercial worth can be superior by improving the superiority and escalating the range of seaweed-based products. Supplementary research is needed to evaluate the nutritional value of marine algae; seaweeds can be regarded as an under-exploited source of health benefit molecules for food dispensation and nutraceutical industry.
The edible green, brown and red seaweeds, Caulerpa racemosa, Sargassum polycystum, cystoseria myrica and Digenia simplex, were analyzed for their nutritional compositions and were then compared to those in many different seaweeds and native vegetables. It absolutely was found that the four seaweeds studied seemed to be fascinating potential sources of plant food proteins due to their high protein levels and balanced amino acid profiles. On the opposite hand the highest carbohydrate contents obtained from the studied species may be used for fermentative production of bioethanol. The results of the current study concluded that these seaweeds will provide dietary alternatives owing to their nutritional values.