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The article contains sections titled: 1. Introduction 2. Analysis and Characterization 3. Pectin 3.1. Occurrence and Structure 3.2. Pectolytic Enzymes 3.3. Production 3.4. Properties 3.4.1. Physical Properties 3.4.2. Gel Properties 3.4.3. Stability and Chemical Reactions 3.5. Analysis 3.5.1. Measurement and Standardization of Gel‐Forming Capacity 3.5.2. Chemical Analysis 3.6. Pharmaceutical and Nutritional Characteristics 3.7. Application in the Food Industry 3.8. Market 4. Alginates 4.1. Occurrence 4.2. Production 4.3. Structure 4.4. Properties 4.5. Propylene Glycol (Propane‐1,2‐diol) Alginate 4.6. Bacterial Alginates 4.7. Analysis 4.8. Applications 4.9. Market 5. Carrageenan 5.1. Structure 5.2. Sources and Raw Materials 5.3. Production 5.4. Analysis 5.5. Properties 5.6. Applications 5.7. Physiological Properties 6. Agar 6.1. Production 6.2. Structure and Gelling Mechanism 6.3. Quick Soluble Agar 7. Gum Arabic 8. Gum Tragacanth 9. Gum Karaya 10. Gum Ghatti 11. Xanthan Gum 11.1. Production 11.2. Structure and Properties 11.3. Analysis 11.4. Applications, Market 12. Gellan Gum 13. Galactomannans 13.1. Structure 13.2. Production 13.3. Properties 13.4. Analysis and Composition of Commercial Preparations 13.5. Derivatives 13.6. Applications 13.7. Market 14. Acknowledgement

Agar-based extracts from Gelidium sesquipedale were generated by heat and combined heatsonication, with and without the application of alkali pre-treatment. Pre-treatment yielded extracts with greater agar contents; however, it produced partial degradation of the agar, reducing its molecular weight. Sonication produced extracts with lower agar contents and decreased molecular weights. A gelation mechanism is proposed based on the rheological and small angle scattering characterization of the extracts. The formation of strong hydrogels upon cooling was caused by the association of agarose chains into double helices and bundles, the sizes of which depended on the agar purity and molecular weight. These different arrangements at the molecular scale consequently affected the mechanical performance of the obtained hydrogels. Heating of the hydrogels produced a gradual disruption of the bundles; weaker or smaller bundles were formed upon subsequent cooling, suggesting that the process was not completely reversible.