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This study aimed to investigate the interaction mechanism of the waxy starch and kappa carrageenan (KC) gel with different ratios during co-gelatinization and storage. Water distributions, mobilities and rheological properties of the mixture gels were studied. When KC concentration was low (0.5%KC and 4% starch), the starch dominated the system, and the gel strength was the lowest. When KC concentration increased to 0.75%, the gel had the lowest change rate of fracture force, and the most homogeneous network of the freeze-dried gel was observed. When KC concentration increased to 1.0%, the gel strength was high, but the uneven structure led to the instability of the gel. Overall, the gel with 0.75%KC and 4% starch was the most stable during storage, and the exclusion of the two components to each other was the weakest, resulting in the uniform structure of the gel., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

New amphiphilic derivatives of kappa-carrageenan (KC) were synthesized by hydrophobic modification with octyl chloride. Two different methods based on microwave and conventional heating were used. All KC derivatives (KCRs) were characterized by different techniques. The FT-IR and 1 HNMR studies demonstrated that the octyl groups were effectively grafted onto KC backbone and confirmed that the derivative KCRMM, obtained by microwave heating, presented a higher degree of substitution (DS = 0.77) compared to KCRCM (0.45). The amphiphilic character investigation also revealed that KCRMM exhibited a lower critical aggregation concentration (CAC) value of 0.13% w/v than KCRCM (0.15%). Furthermore, KCRs greatly improved the stability of oil/water emulsions as the droplet size decreased with increasing DS. Unlike the conventional heating method, novel derivatives with a higher DS, greater amphiphilic character, and an improved emulsifying power were obtained by microwave-assisted synthesis. These derivatives could potentially be used in food, cosmetics, or as excipients in pharmaceutics., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Usually to prepare a gel from kappa carrageenan, an aqueous dispersion of carrageenan powder is heated. This research presents evidence of cold gelation of carrageenan dispersions while no heat is needed. The occurrence of cold gelation is investigated in the absence or presence of potassium ions during ultrasound treatment by studying the mechanical and microstructural properties of the prepared gels using a texture analyzer and scanning electron microscopy, respectively. Carrageenan gels were obtained by applying power ultrasound. By increasing sonication time, gel hardness increased up to a certain level (in absence or presence of K(+) during ultrasound treatment) and further ultrasound application had a negative effect. Moreover, the mechanical properties of the gels in which K(+) ions were added before ultrasound were weaker than the samples when K(+) ions were added after sonication. Relaxation times of gels were calculated using the generalized Maxwell model with three elements., (Copyright © 2013. Published by Elsevier Ltd.)