Species Of Edible Seaweeds Research Articles

Variation in heavy metals concentrations among seaweed species from Mkwiro seaweed farm, Kwale County, Kenya

This study, conducted at the Mkwiro seaweed farm in Kwale County, Kenya, aimed to assess the concentrations of heavy metals (Cd and Pb) and essential elements (Na, Fe, Ca, and K) in selected edible seaweed species. The study used a cross-sectional, descriptive research design and probability sampling method to collect data. Seaweed samples of three selected species, Cottonii (Kappaphycus alvarezii), Sea lettuce (Ulva lactuca), and Bubble-green seaweed (Boergesenia forbesii) were collected in quadrants and subjected to chemical analysis. Statistical analyses were conducted using R Studio version 4.3.2, with a significance level set at α=0.05. The Kruskal-Wallis test revealed significant differences in lead concentrations among seaweed types (χ² (2) = 7.01, p = 0.03). Cadmium concentrations did not show significant differences (χ² (2) = 3.88, p = 0.14). For calcium concentrations, ANOVA indicated no significant effect of seaweed type (F (2,33) = 0.6381, p = 0.5347). Iron concentrations differed significantly among seaweed types (χ² (2) = 23.35, p = 0.00000849), with B. forbesii having the highest median concentration. Potassium and sodium concentrations did not significantly vary among seaweed types (p > 0.05). The study uncovers elevated cadmium levels in seaweed, indicating potential contamination risks. However, concentrations of essential elements were lower. To address these findings, it is recommended to initiate regular monitoring and pollution control measures in seaweed farms. Additionally, diversifying cultivation with low-metal species can enhance product safety and quality.

Potential of Edible Seaweed of the Kenyan Coast as a Micronutrient Source

Edible seaweed, a rich source of micronutrients, remains underutilized despite its availability at the Kenyan coast, while micronutrient deficiencies remain a major health concern in Kenya. The study assessed micronutrient content of randomly sampled seaweed and consumption patterns, interviewing 175 seaweed farmers and analysing 58 samples from Mombasa, Kilifi, and Kwale counties. Micronutrients (vitamin A, D, B9, B12, iron, zinc, iodine) and heavy metals (mercury, lead, arsenic, cadmium) were measured. Predominantly female seaweed farmers, aged 30-40, with low income and education levels, focused on commercial farming over personal consumption due to limited nutritional awareness. A diverse array of edible seaweed species was identified; 11 Phaeophyceae (Sargassum, Turninaria, Dictyota, Padina, Eucheuma), 9 Chlorophyta (Ulva, Caulerpa, Eucheuma) and 8 Rhodophyta (Gracilaria, Hypnea, Soliera, Eucheuma). Significant regional and species variations were observed; Kilifi samples had higher vitamin A (p= 0.031), D (p=0.047), B9 (p=0.006), Kwale exhibited elevated iron levels (p= 0.047). Green phyla showed higher vitamin B12, D, zinc, iodine levels, while red phyla were rich in vitamin B9, A, and iron. Eucheuma cotonii had the highest vitamin B12 (696.6 μg/100 g) and vitamin A (298.6 μg/100 g) levels, Ulva intestinalis recorded highest iron (637.85 mg/kg) and Caulerpa taxifolia had highest zinc (277.74 mg/kg). Though some species contained traces of lead and cadmium within permissible limits, mercury was found in only four species, with no arsenic detected. Increasing awareness of seaweed's nutritional value is crucial to combatting micronutrient deficiencies, alongside further research into processing, value addition, market integration, and heavy metal mitigation strategies. Keywords; Edible seaweed, Micronutrients, Micronutrient deficiencies, Kenyan coast

Biochemical and Nutritional Characterization of Edible Seaweeds from the Peruvian Coast.

In Peru, the number of species of edible seaweeds within the genera Chondracanthus, Porphyra (hereafter P.), Pyropia (hereafter Py.), and Ulva has not been fully established, nor is there a significant level of information available related to their chemical and nutritional composition. This study involved the biochemical analysis of species belonging to ten genera of macroalgae, known edible and some of which have the potential to be used as food, including six red (Callophyllis, Chondracanthus, Mazzaella, Porphyra, Pyropia, and Rhodymenia), two green (Ulva and Codium), and two brown (Eisenia and Lessonia) species collected along the Peruvian coast (6°-17° S). In the evaluation of 37 specimens, differences were found in the proximal composition, amino acid composition, and fatty acid profiles, which were specific to subgroups and supported their taxonomic classification, mainly at the order level. The red algae Porphyra/Pyropia (Bangiales) had the highest average percentage of protein (24.10%) and carbohydrates (59.85%) and the lowest percentage of ash (7.95%). Conversely, the brown alga Eisenia (Laminariales) had the lowest average percentage of protein, with different values related to the structure: 14.11% at the level of the frond and 9.46% at the level of the stipe. On the other hand, Bryopsidales green algae showed the highest average percentages of lipids (5.38%). The moisture percentages ranged from 4 to 16%, and no relevant significant differences were shown between the orders. The characteristic amino acids in all of the studied groups were glutamic acid, aspartic acid, alanine, and leucine. The highest average of the essential amino acids ratio was obtained for the Gigartinales red algae (48.65%), and the highest values of the essential amino acid index (EAAI) were obtained for the Ulvales, Laminariales, Gigartinales, and Rhodymeniales algae (EAAI > 0.92). The highest average relative percentage of fatty acids was obtained for polyunsaturated fatty acids, followed by saturated fatty acids. The major component of the ω6 fatty acids from red and brown algae was arachidonic acid (C20:4n - 6). The highest level of ω3 fatty acids was observed for the eicosapentaenoic acids (EPA) in red algae. The highest median ω6/ω3 ratio was displayed by the red alga Callophyllis variegata (Gigartinales). A detailed knowledge of edible seaweeds, and those considered potentially edible, would help to diversify the diet based on macroalgae in Peru.

New Analytical Strategy for Bioaccessibility Evaluation of Bromine and Iodine from Edible Seaweeds.

A strategy for determining the bioaccessibility of bromine and iodine from edible seaweeds was proposed for the first time using microwave-induced combustion (MIC) and ion chromatography coupled to mass spectrometry (IC-MS) after in vitro digestion. The concentrations of bromine and iodine in edible seaweeds using the proposed methods (MIC and IC-MS) were not statistically different from those using MIC and inductively coupled plasma mass spectrometry (p > 0.05). Trueness was assessed by recovery experiments (101-110%, relative standard deviation <10%). Following an in vitro digestion protocol, MIC was proposed as sample preparation for bioaccessible and residual fractions. Using this strategy, the mass balance totaled from 97 to 111%. No statistical difference (p > 0.05) was observed between the total concentration of bromine or iodine and their concentration in bioaccessible and residual fractions for three edible seaweed species, indicating full analyte quantification in the fractions.

Trust your seaweeds: Fine-scale multi-elemental traceability of edible seaweed species harvested within an estuarine system

Seafood traceability is a matter of concern for producers and consumers, providing insights that can simultaneously inform the consumers on the origin of the product, nutritional value and safety while adding market value to the products. Edible seaweed harvest has been pointed out as an environmentally friendly sustainable food production solution. Ulva spp. and Fucus vesiculosus are among the most abundant naturally occurring estuarine seaweeds with high biomass production on the Portuguese coast, making them a potentially important seafood resource. Seaweed elemental signatures chemometric analysis made it possible to confirm species authenticity with 100 % accuracy, which can be of major importance for powdered seaweed food supplements certification. Using the seaweed thallus elemental signatures through Variable Importance in Projection Partial Least-Squares Discriminant Analysis (VIP-PLS-DA) it was also possible to pinpoint the harvest location of the seaweeds with 82.5 and 92.5 % accuracy for F. vesiculosus and Ulva respectively. These same multi-elemental signatures were also able to depict the harvest season of the seaweeds (100.0 and 85.0 % accuracy for F. vesiculosus and Ulva respectively). Analysing the elements with higher importance for the PLS-DA models, it was evident that several elements with higher discriminatory ability are linked to anthropogenic sources. Considering the anthropogenic pressure gradient in the Tagus estuary, it is no surprise that these elements have a fine-scale spatial variability. While providing key models for fine-scale spatial traceability of seaweeds, the multi-elemental signatures here presented also provide key insights on their nutritional value in terms of recommended mineral daily intake, given that in some of the harvest areas analysed, seaweed thallus presented values above the maximum admissible threshold for human consumption. Thus, the developed models can be of added value for seaweed consumers, authorities and stakeholders, namely for the safe and sustainable development and monitoring of conservation and harvesting plans within estuarine systems.

Proximate Composition, Physicochemical and Microbiological Characterization of Edible Seaweeds Available in the Portuguese Market.

The aim of this work was the study of the proximate composition and profile of fatty acids, minerals, and some microbiological aspects of four edible seaweed species (Chondrus crispus, Palmaria palmata, Porphyra sp., and Ulva sp.) available in the Portuguese market for food consumption, and produced in a national Integrated Multi-Trophic System (IMTA). Moisture, ash, and total lipids were determined gravimetrically. Crude protein was analysed by Duma's combustion procedures. The total carbohydrate content was assayed by the phenol/sulphuric acid method. The assessment of the fatty acids methyl esters (FAMEs) was determined through GC-MS. Characterization of elemental analysis was performed by ICP-AES. Different standard microbiological methods were applied for microorganisms. Statistics were performed using the non-parametric Mann-Whitney U test to assess significant differences between samples. Lipid contents (n = 3) were very low (1.6-2.3%), particularly in Palmaria palmata, and Chondrus crispus (1.6-1.7%). The protein content (n = 4) varied from 14.4% in P. palmata to 23.7% in Porphyra sp. Carbohydrates (n = 3) were the major constituent of most seaweeds (31-34%), except in Porphyra sp., with higher content in proteins than carbohydrates. Regarding the fatty acid content (n = 4), in general, saturated fatty acids (SFAs) were the most abundant followed by polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs). Among macro and trace elements (n = 3), Chondrus crispus shows the highest average content in Zn (71.1 mg ⋅ kg - 1 D.W.), Palmaria palmata the highest average content in K (124.8 g ⋅ kg - 1 D.W.), Porphyra sp. the highest average content in P (2.1 g ⋅ kg - 1 D.W.), and Ulva sp. the highest average content of Ca (5.5 g ⋅ kg - 1 D.W.), Mg (55.8 g ⋅ kg - 1 D.W.), and Fe (336.3 mg ⋅ kg - 1 D.W.). In general, Na and K were the most abundant elements among analysed seaweed. Additionally, the microbiological results (n = 4) comply with the Portuguese guidelines (subgroup 2D) on the application of general principles of food hygiene in ready-to-eat foods. Overall, the results highlight the potential of using these seaweeds as an alternative and sustainable source of elements and bioactive compounds to produce enriched food products with a beneficial potential for human nutrition.

Antioxidant properties of edible sea weed from the Northern Coast of the Sea of Japan

Introduction. New natural antioxidants remain a relevant research task of food science. Natural antioxidants neutralize free radicals in food systems, as well as in human body. The antioxidant properties of seaweed have attracted scientific attention for many years. However, most experiments featured non-polar extracts while aqueous extracts still remain understudied. The present research objective was to evaluate the antioxidant properties of hydrothermal extracts of edible seaweed from the Northern Coast of the Sea of Japan.&#x0D; Study objects and methods. The study featured hot-water and autoclave (30 and 60 min) extracts of three edible seaweed species from Russia’s Far East. The research focused on dry matter yield, total phenol content, phenolic profile, antiradical properties, hydroxylion (OH•) scavenging activity, and superoxide radical (O2•−) scavenging activity.&#x0D; Results and discussion. The hot-water extracts appeared to have a higher yield than the autoclave extracts. The hot-water extract of red-purple seaweed Gracilaria verrucosa had the highest yield – 15.90%. The extract of brown seaweed Sargassum miyabei demonstrated the highest total phenol content. The phenolic profile of the extracts revealed 10 compounds, syringic acid and epicatechin being the major ones. The radical scavenging activity of the extracts varied from 48.2 to 88.9%, the highest value was observed in the hot-water extract of S. miyabei. The autoclave S. miyabei extracts also had a high radical scavenging activity, which exceeded other samples by 5.0–13.3%. The hot-water (30 min) extract of G. verrucosa had the lowest antiradical activity. Hot-water and autoclave extracts of S. miyabei showed the best OH• scavenging activity. Only the samples of G. verrucosa demonstrated signs of superoxide radical scavenging.&#x0D; Conclusion. The extracts of brown seaweed S. miyabei proved to be the most active. The hot-water and autoclave extracts had the highest total phenol content and the strongest DPPH and OH• inhibitory activity.

Determination of total iodine content in edible seaweeds: Application of inductively coupled plasma-atomic emission spectroscopy

Iodine is an essential element necessary for the synthesis of thyroid hormones, and its deficiency is a common problem worldwide. To avoid iodine insufficiency, the intake of this element must be properly evaluated concerning its adequate intake (AI), which is estimated at 90, 150, and 200 μg per day, for children, adults, and pregnant women, respectively. One of the most abundant resources available for iodine is the consumption of edible seaweeds. In this work, ten species of edible seaweeds: one green (Ulva rigida), five red (Chondracanthus teedei var. lusitanicus, Chondrus crispus, Gracilaria gracilis, Grateloupia turuturu, Osmundea pinnatifida), and four brown species (Bifurcaria bifurcata, Fucus vesiculosus, Saccorhiza polyschides, Undaria pinnatifida), collected from the near-pristine Portuguese seashore, were analyzed for iodine content. The iodine concentration was determined by optimized microwave-assisted extraction in aqua regia (AR), followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis. The method was validated by using the standard reference material (kelp) obtaining a maximum recovery of 100 ± 15%. The studied species contained a wide range of iodine concentrations, ranging from 33 ± 3 μg g−1 dry weight (dw) (U. rigida), up to 302 ± 26 μg g−1 dw (O. pinnatifida), 352 ± 21 μg g−1 dw (F. vesiculosus) and 391 ± 24 μg g−1 dw (B. bifurcata). The results show that the analyzed seaweeds can serve as a beneficial resource for iodine, however, their consumption must be balanced in a way that does not exceed the adequate estimated iodine intake for population groups.

Cheese supplementation with five species of edible seaweeds: Effect on proteolysis, lipolysis and volatile compounds

The effect on the biochemical characteristics of Ibérico semi-hard cheese supplemented with Himanthalia elongata (HE), Laminaria ochroleuca (LO), Porphyra umbilicalis (PU), Ulva lactuca (UL) or Undaria pinnatifida (UP) seaweeds was investigated. Addition of 1% dehydrated seaweed to curd increased total free amino acids in LO cheese and decreased them in HE and UP cheeses at 60 days with respect to control cheese. Lipolysis was markedly enhanced in UL cheese, which showed on day 60 a 6.0-fold higher concentration of total free fatty acids than control cheese. Seventy-six volatile compounds were detected in cheeses with seaweeds and 54 in control cheese. Aldehydes and alcohols reached higher levels in the control cheese, esters and ketones in PU cheese, acids and sulphur compounds in UL cheese, hydrocarbons in HE and PU cheeses, and furans in HE and UP cheeses.

Variations in polyphenol and heavy metal contents of wild-harvested and cultivated seaweed bulk biomass: Health risk assessment and implication for food applications

Seaweeds are increasingly used in European cuisines due to their nutritional value. Many algal constituents, such as polyphenols, are important antioxidants and thus considered beneficial to humans. However, many seaweed species can accumulate heavy metals and exhibit potential health risks upon ingestion. We investigated temporal and spatial variations in polyphenol and heavy metal (As, Cd, Hg, Pb) concentrations of three edible seaweed species. The brown algae Saccharina latissima and Alaria esculenta, and the red alga Palmaria palmata were sourced from natural populations and aquaculture in the NE Atlantic and processed as bulk biomass mimicking industrial scales. The mean polyphenol content was species-specific (Alaria > Saccharina > Palmaria), and highest in winter (for Alaria and Saccharina) and spring (for Palmaria); inter-annual and spatial variations were marginal. Heavy metal concentrations varied between species and depended on collection site, but seasonal variations were minimal. Our data suggest that all three species are good sources of antioxidants, and the heavy metal concentrations are below the upper limits set by the French recommendation and the EU Commission Regulation on contaminants in foodstuffs. A health risk assessment indicated that consumption of these seaweed species poses a low risk for humans with regard to heavy metals. However, an EU-wide regulation on maximal concentration of heavy metals in seaweeds should be established.

Edible seaweeds’ phlorotannins in allergy: A natural multi-target approach

The anti-allergenicity of phlorotannin-targeted extracts from four edible seaweed species of Fucus genus was evaluated herein for the first time. Extracts were able to act upon cellular events triggered by immunological reaction (IgE/antigen), and on cellular events downstream the Ca2+ influx caused by a chemical stimulus (calcium ionophore A23187), preventing degranulation of RBL-2H3 cells. Furthermore, a dose-dependent behaviour towards allergy-related enzymatic systems was observed for all the phlorotannin extracts. Linear correlations were found between reduction of the allergic mediators released and the total phlorotannin content, as well as between the enzyme inhibition and the amount of phlorotannins in the extracts. These results point to a multi-target anti-allergic capacity of phlorotannin-targeted extracts, which displayed effects on different critical steps of the allergic response, contributing to the valorisation of Fucus spp. both as food and for nutraceutical applications.

Cheese supplementation with five species of edible seaweeds: Effect on microbiota, antioxidant activity, colour, texture and sensory characteristics

Supplementation of dairy products with non-dairy ingredients with the aim of increasing the concentration of particular nutrients is a common industrial practice. In the present study, a semi-hard cheese was supplemented with each of five seaweeds (Himanthalia elongata, Laminaria ochroleuca, Porphyra umbilicalis, Ulva lactuca, Undaria pinnatifida). Addition of 10 g of dehydrated seaweed per kg of curd caused significant differences in dry matter and pH value, but it hardly influenced cheese microbiota. Antioxidant activity, which was correlated with total phenolic compounds, was significantly higher in cheese supplemented with H. elongata than in control cheese. Instrumental colour and texture parameters of cheese varied significantly with the added seaweed species. Cheeses supplemented with H. elongata, U. pinnatifida and L. ochroleuca received odour and flavour quality scores from panellists that did not differ from those of the respective control cheese until day 60 and were associated with low seaweed odour and flavour scores.

Iodine content in bulk biomass of wild-harvested and cultivated edible seaweeds: Inherent variations determine species-specific daily allowable consumption

This study represents a large-scale investigation into iodine contents in three commercially important and edible seaweed species from the North Atlantic: the brown algae Saccharina latissima and Alaria esculenta, and the red alga Palmaria palmata. Variability among and within species were explored in terms of temporal and spatial variations in addition to biomass source. Mean iodine concentration in bulk seaweed biomass was species-specific: Saccharina > Alaria > Palmaria. Iodine contents of Saccharina biomass were similar between years and seasons, but varied significantly between sampling locations and biomass sources. In Alaria and Palmaria, none of the independent variables examined contributed significantly to the small variations observed. Our data suggest that all three species are rich sources of iodine, and only 32, 283, or 2149 mg dry weight of unprocessed dry biomass of Saccharina, Alaria, or Palmaria, respectively, meets the recommended daily intake levels for most healthy humans.

Characterisation and chemometric evaluation of 21 trace elements in three edible seaweed species imported from south-east Asia

This study was performed to delineate a characterisation of 21 trace elements (Al, As, Be, Cd, Co, Cr, Cu, Fe, Hg, Mo, Mn, Ni, Pb, Sb, Se, Sn, Sr, Tl, U, V, and Zn), in 92 samples of edible seaweeds, belonging to three species (Laminaria Japonica, 16; Porphyra Yezoensis, 54; Undaria Pinnatifida, 22) produced in south-eastern Asiatic countries. Analytical method based on inductively coupled plasma mass spectrometry was used. The compliance of samples with current European regulations was investigated and the 26% of samples was found not-compliant for Cd level. The suitability of the method due to multi-elemental determination allowed a multivariate approach to study the differentiation between species and to investigate the contribution of each element in differentiation. Influence of the geographical origin onto trace element profile was evaluated, and correlation study between each pair of elements was performed by Pearson coefficients. Taxonomic genus and, although to a lesser extent, the geographic origin have a great influence on trace element profile. Comparison with other similar studies was also performed. Discussion on safety aspects concerning heavy metal exposure related to seaweed consumption has been addressed, by comparing the tolerable levels of the most important toxic elements and the intake brought by seaweed species. For some toxic metals, such as Al and Cd, a remarkable risk related to seaweed consumption has been assessed, though with differences between species.

Macromolecular Antioxidants and Dietary Fiber in Edible Seaweeds.

Seaweeds are rich in different bioactive compounds with potential uses in drugs, cosmetics and the food industry. The objective of this study was to analyze macromolecular antioxidants or nonextractable polyphenols, in several edible seaweed species collected in Chile (Gracilaria chilensis, Callophyllis concepcionensis, Macrocystis pyrifera, Scytosyphon lomentaria, Ulva sp. and Enteromorpha compressa), including their 1st HPLC characterization. Macromolecular antioxidants are commonly ignored in studies of bioactive compounds. They are associated with insoluble dietary fiber and exhibit significant biological activity, with specific features that are different from those of both dietary fiber and extractable polyphenols. We also evaluated extractable polyphenols and dietary fiber, given their relationship with macromolecular antioxidants. Our results show that macromolecular antioxidants are a major polyphenol fraction (averaging 42% to total polyphenol content), with hydroxycinnamic acids, hydroxybenzoic acids and flavonols being the main constituents. This fraction also showed remarkable antioxidant capacity, as determined by 2 complementary assays. The dietary fiber content was over 50% of dry weight, with some samples exhibiting the target proportionality between soluble and insoluble dietary fiber for adequate nutrition. Overall, our data show that seaweed could be an important source of commonly ignored macromolecular antioxidants.

Assessment of the Antioxidant and Antibacterial Activities of Three Species of Edible Seaweeds

Extraction of secondary metabolites from St. Lawrence Estuary edible seaweeds – Saccharina longicruris, Ascophyllum nodosum and Ulva lactuca – was carried out by pressurized liquid extraction using ethanol. The antioxidant potential of extracts was evaluated through DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, oxygen radical absorbance capacity and ferric reducing antioxidant power assays, and the antibacterial activity was tested against food spoilage bacteria: Escherichia coli, Micrococcus luteus and Brochothrix thermosphacta. Of all seaweed extracts, A. nodosum exhibited the highest phenolic and carotenoid contents, 50.2 mg GAE/g and 85 μg/g, respectively. A. nodosum also displayed the best DPPH scavenging activity, EC50 10.4 μg/mL, and best capacity to reduce ferric ion, 677.2 μmol TE/g dry weight at a concentration of 100 μg/mL. U. lactuca extracts showed the highest growth inhibition of E. coli, 69.5%; M. luteus, 61.4%; and B. thermosphacta, 21.4%. These findings suggest a high potential of St. Lawrence Estuary seaweed extracts for application in the food industry. Practical Applications Food producers, food industries, governments and consumers are aware of the importance to look into effective preventive measures in food quality and food safety fields. The decay of foods is caused by physical, chemical and biological factors, which leads to the loss of the organoleptic characteristics and consumer safety. Natural extracts combining both antioxidant and antibacterial activities can be used for further applications in reducing food spoilage and prolonging food shelf life. The majority of natural extracts could be approved as Generally Recognized As Safe (GRAS). St. Lawrence Estuary seaweed extracts possess high potential for application in the food industry using pressurized liquid extraction (PLE) method, which was selected for extraction efficiency purposes. In addition, production of seaweeds extracts using approved food-grade ethanol solvent by PLE method involves, on an industrial scale, cost savings.

식용해조류 6종의 페놀성화합물 함량 및 항산화 활성

갈조류(미역, 톳, 다시마), 홍조류(김, 꼬시래기) 및 녹조류(파래) 등 식용해조류 6종으로부터 제조한 추출물의 페놀성 화합물 함량과 항산화 활성을 분석하였다. 추출수율은 꼬시래기 분말을 물(pH 8.0)을 용매로 추출하였을 때 가장 높았으며(44.23 %), 페놀성 화합물은 톳을 75 % 에탄올 용액으로 추출하였을 때 가장 높았다(52.82 <TEX>${\mu}g/mg$</TEX>). 25% 에탄올 용액으로 추출한 파래 추출물에서 가장 높은 DPPH 라디칼 소거활성이 나타났으며(19.29 %), superoxide 음이온 소거활성은 다른 해조류 추출물에 비해 물(pH 8.0)로 추출한 톳 추출물(81.20 %)에서 더 높았다. 6종의 식용해조류 추출물에서의 페놀성 화합물의 함량은 항산화 활성과 강하게 상관관계를 보였다(R2=0.852). 종합해 보면, 이러한 결과는 갈조류인 톳이 천연 항산화제 개발을 위한 좋은 원료가 될 수 있음을 의미한다. Phenolic contents and antioxidant activities were determined in the water and ethanol extracts from six species of edible seaweeds, Phaeophyceae (Laminaria japonica, Hizikia fusiformis and Undaria pinnatifida), Rhodophyceae (Porphyra tenera and Gracilaria verrucosa) and Chlorophyceae (Ulva lactuca). The highest extraction yield was observed in water extract (pH 8.0) of G. verrucosa (44.23 %) and phenolic content was the highest in ethanolic (75 %) extract of H. fusiformis (52.82 <TEX>${\mu}g/mg$</TEX>). 25 % ethanolic extract from U. lactuca was found to have the highest DPPH radicals scavenging activity(19.29 %) and superoxide anion scavenging activitiy was higher in water extract (pH 8.0) from H. fusiformis (81.20 %) than that other seaweeds. Phenolic contents were strongly correlated with antioxidant activity in the six edible seaweeds extracts (<TEX>$R^2$</TEX>=0.852). Taken together, these results indicate that H fusiformis may be a excellent source for development of natural antioxidants.

SEASONALITY OF SELECTED NUTRITIONAL CONSTITUENTS OF EDIBLE DELMARVA SEAWEEDS.

Edible seaweeds have not been thoroughly explored for food, medicinal, or industrial purposes in the United States. This study compared selected proximate constituents of three edible seaweed species (Ulva lactuca L., Fucus vesiculosus L., and Gracilaria tikvahiae McLachan) at two sites for possible future development as a food crop on the Delmarva Peninsula. Sampling was conducted bimonthly at Chincoteague Memorial Park, Virginia, and Indian River Inlet, Delaware, from 2005 to 2008. Proximate constituents of moisture, ash, dietary fiber, proteins, and fat were measured seasonally and calorific values were calculated. Data were analyzed using correlation, paired samples t-tests and one- and two-way ANOVA. Significant variations in the proximate constituents were found among seasons, species, and between sites. The brown seaweed (Fucus) at both sites had higher fiber, fat, and ash (mineral) content than the green (Ulva) or the red (Gracilaria). Ulva and Gracilaria had higher protein content than Fucus. Seaweeds from Delaware had more fat, ash, and protein than from Virginia, potentially because of the more polluted, nutrient rich environment at the Delaware site. Positive correlations between seaweed fat and protein content may indicate an increase in the synthesis of both components under optimal growth conditions. Species' physiology differences and the water quality at the two sites likely impacted proximate constituent values. This study contributed new information to the existing body of knowledge in the areas of nutrition and ecology of seaweeds and their potential as a cash crop.

Estimation of total as well as bioaccessible levels and average daily dietary intake of iodine from Japanese edible seaweeds by epithermal neutron activation analysis

An epi-thermal instrumental neutron activation analysis (EINAA) method in conjunction with Compton suppression spectrometry (EINAA-CSS) was used for the determination of total iodine in eight different species of edible seaweeds from Japan. This method gave an absolute detection limit of about 2 μg. The accuracy of the method was evaluated using various reference materials and found to be generally in agreement within ±6% of the certified values. The longitudinal distributions of iodine at different growing stages in Japanese sea mustard and tangle seaweeds were investigated. For a 150-cm-high tangle, the highest concentration (5,360 mg/kg) of iodine was found at the root, then decreased slowly to 780 mg/kg in the middle portion (60–75 cm), and increased to 2,300 mg/kg at the apex. On the other hand, for a 190-cm-high sea mustard the highest levels of iodine were found both at the roots (164 mg/kg) and apex (152 mg/kg) with lower values (98 mg/kg) in the middle section. In order to estimate the bioaccessible fraction of iodine, seaweeds were digested by an in vitro enzymolysis method, dietary fibre separated from residue, and both fractions analyzed by EINAA-CSS. The average daily dietary intakes of total (0.14 mg) as well as bioaccessible fraction (0.12 mg) of iodine from the consumption of sea mustards were estimated.

Nutritional analysis of Vietnamese seaweeds for food and medicine

Vietnamese edible marine macro-algae (seaweed) are of interest because of their value in nutrition and medicine. Vietnamese living in the coastal have traditionally utilized seaweeds species as food supplement and herbal medicine. They consumed seaweed as food in various forms: raw as salad and vegetable, pickle with sauce or with vinegar, relish or sweetened jellies and also cooked for vegetable soup. As herbal medicine, seaweed is usually used for traditional comestics, treatments for cough, asthma, hemorrhoid, boils, goitres, stomach ailments, urinary diseases, reduce the incidence of tumors, ulcers and headaches. Although Vietnam has an abundance of algae floral with total number of species is estimated to be nearly 1000 spp. in which there are 638 species of marine algae identified. However, there have been no intense study regarding to changes in marine algal chemistry. The fifteen species of edible seaweeds studied in this paper include green, brown and red algae. The proximate compositions as ash, protein, lipid, carbohydrate, fatty acids, vitamins, pigments, macro and micro-elements were compared among different species examined and the genetic relationships among them by analyzing the species-specific differences in nucleotide sequences of ITS-1 region of the ribosomal DNA was identified.