Agar Extraction, Physical Properties, FTIR Analysis and Biochemical Composition of Three Edible Species of Red Seaweeds Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S. G. Gmelin)........

Three species of red algae Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S.G. Gmelin), Steentoft, L. M; Irvine and Farnham (formerly Gracilaria verrucosa (Hudson) were collected from four different sites (Buleji, Hawks Bay, Manora and Paradise Point) of Karachi coast. The G. corticata was the dominant species and the highest yield of agar was compared to other studied species. The physical properties such as gel temperature, melting temperature, density, viscosity and gel strength showed large variations. Interestingly, the gel temperature, melting temperature, density, and gel strength had the highest value in G. corticata samples collected, while gel viscosity recorded the highest value in G. dentata samples. Intensive spectroscopic FTIR analysis was determined in all three species of G. corticata, G. dentata and G. longissima. The bands at 414.7/cm to 3917.2/cm represents stretching and bending vibrations of alcohol O-H, amine N-H, alkane C-H, alkyne C=C, nitriles C=N, carboxyl C=O, nitro aromatic N=O, alkane C-C, nitro methane C-N, aliphatic amines C-N, sulfoxides S=O, alkene C-H alkyl halide C-Cl, C-I groups. The ash content of all studied species (G. corticata, G. dentata and G. longissima) was in the range of 20-30%, while the carbohydrate content was in the range of 22-24%. The results of this study suggested the utilization of our natural resources present in Karachi coast. This could be achieved by determining the quantity and quality of agar in the edible species of Gracilaria/Gracilariopsis.

Seasonal studies on the carbohydrate content of some marine macroalgae in Gulf of Mannar coastal region, India

Carbohydrates were analysed in 40 species of marine macroalgae belonging to three classes collected at seasonal intervals between April 2018 to March 2019 from the intertidal habitats in Gulf of manner coastal regions.Among the 40 dominant seaweeds 11 species belonged to Chlorophyceae, 13 species to Phaeophyceae and the remaining 16 species to Rhodophyceae. The carbohydrate content of seaweeds varied from 4.50±0.12 to 72.25±3.15 % of DW during the summer season. The percentage of carbohydrate content was maximum in Gracilaria verrucosa (72.25±3.15 % of DW) during the summer season and minimum in Turbinaria ornata (4.50±0.12 DW) during the summer season. The carbohydrate content of seaweeds varied from 5.50±0.17 to 48.38±3.04 % of DW during the pre-monsoon season. The maximum values were observed in Gracilaria corticata var. corticata the minimum content was observed in Padina pavonica. The carbohydrate content of seaweeds varied from 4.83±0.12 to 58.18±4.56 % of DW during the monsoon season. The maximum value was observed in Gracilaria corticata var corticata and the minimum was in Padina pavonica. The carbohydrate content of seaweeds varied from 7.36±0.16 to 67.25±2.41 % of DW during the post-monsoon season. The maximum value was observed in Acanthophora spicifera and the minimum content was observed in Sargassum ilicifolium.

Preparation and Characterisation of Starchy Foods by Plant Polymers from Abelmoscus esculentus Agro Waste and Gracilaria corticata - for Commercial Food Applications

Objective: The surface modification of high temperature processed potato chips by structurally stable carbohydrate polymer from Abelmoscus esculentus and Gracilaria corticata were studied. The 1% A. esculentus carbohydrate polymer surface coated chips had less coating pick up than the chips coated with a combination of polysaccharide 1% A. esculentus + Gracilaria corticata polysaccharide. Methods: The mucilage polysaccharides were extracted from the A. esculentus and Gracilaria corticate by hot solvent extraction. The mucilage coating solutions were prepared at 1% concentration individually and in combination for coating the potato strips. The proximate analysis and characterisation of edible coated potato chips were investigated. Results and Discussion: The proximate analysis of carbohydrate polysaccharide coated potato chips showed a reduction in terms of fiber, ash, reducing sugar with a corresponding increase in protein content than control snacks without any coating treatment. The instrumental textural analysis revealed that maximum force required puncturing the surface structure of 1% A. esculentus and 1% A. esculentus + Gracilaria corticata was 16.3-14.04N and 16.95-14.17N which was higher than the force required for puncturing the surface structure of control chips (15.4-13.3N). The instrumental color analysis was performed by image analysis technique, and the effect of the color values of the structural polysaccharide on snack surface were expressed as L*a*b* values. Conclusion: The structural stability of both polysaccharides obtained by fracture force was well in agreement with all of the sensory attributes which showed that they could act as structurally stable polymers that could yield the highest crispiness value for the potato chips with better consumer acceptance.