Hot water extraction, a sizable quantity of fibers were dispersed within the agar answer and filtered out with all the agar inside the approach of stress filtration. In addition, the presence of sulfate groups within the structure may cause electrostatic repulsion amongst the polysaccharide chains. The decreased entanglement of the polysaccharide chain possibly resulted within the decreased viscosity. Immediately after alkaline pretreatment, the degree of chain entanglement enhanced together with the raise on the three,6-AG content, therefore major for the higher viscosity. ML-SA1 Description Additionally, the viscosity of agar solution also is dependent upon the molecular weight or the chain length of molecules [26]. Yarnpakdee et al. [14] found that viscosity of agar from G. tenuistipitata pretreated with NaOH at all concentrations utilised was higher than these pretreated with KOH mainly because the polysaccharide chain may be further degraded by KOH. Meanwhile, agar extracted from G. tenuistipitata with higher alkaline concentration (7 NaOH, w/v) showed a decreased viscosity. Similarly, Praiboon et al. [11] reported that the decrease in viscosity of agar pretreated with five NaOH was due to the hydrolysis of the polysaccharide chain by alkaline. In general, the viscosity could reflect the purity or high quality on the solution. In production, the viscosity of agar could also be adjusted by different pretreatment methods based on the actual desires. Dissolving, gelling, and melting temperatures of agars with diverse treatments are presented in Table 1. The native agar from G. tenuistipitata showed lower gelling and melting temperatures of 30.four C and 82.eight C, respectively. It was discovered that native agars from G. corticata from collected from Kenya, G. tenuistipitata collected from the Philippines, and G. blodgettii and G. crassissima collected from the Yucatan Peninsula showed distinctive gelling and melting temperatures, and their gelling and melting temperatures are inside the variety of 425 C and 868 C, respectively [279]. The gelling and melting temperatures differ based around the location exactly where the algae are harvested. In addition, each gelling and melting temperatures are impacted by distinctive extraction processes. For agar with alkaline pretreatment for the duration of alkali extraction (7 NaOH, w/v) and enzyme-assisted extraction (three NaOH, w/v), these with NaOH pretreatment formed gel at temperature of 42.4 C and 34.eight C, respectively, and also the corresponding gels molt at 86.4 C and 84.four C. That is definitely, agar with higher gelling and melting temperatures is usually extracted from G. tenuistipitata immediately after alkaline pretreatment. The higher melting temperature is attributed to the higher power essential to cleave the network, indicating that the alkali pretreated agar gels had been more stable than native agar. The higher melting temperature is ascribed to the high energy necessary to break down the network, indicating that the agar gel with alkaline pretreatment have been more steady than native agar [30]. Tianeptine sodium salt Cancer Villanueva et al. [30] reported that the gelling and melting temperatures of native agar from G. vermiculophylla have been the 21.66.four C and 62.70.0 C, respectively; however, both gelling and melting temperatures rose to 31.05.8 C and 73.60.4 C, respectively, when G. vermiculophylla was treated with 4 NaOH. Furthermore, the substitution degree of methoxy group on the agar polysaccharide chain was also certainly one of vital things affecting the gelling temperature. The amount and location of sulfate groups had been also thought to inhibit or delay the gelation mecha.
