<![CDATA[General Background Seaweed represents a vital fishery commodity with extensive applications across the food, pharmaceutical, and cosmetic industries. Specific Background Gracilaria verrucosa, a prominent red algae species, yields agar molecules whose functional characteristics depend heavily on extraction conditions. Knowledge Gap Standard extraction pretreatments utilizing weak acids often fail to maximize agar recovery and functional parameters from algal cell structures. Aims This study evaluates the combination of strong alkali (NaOH) and strong acid (HCl) pretreatments on the physical characteristics of Gracilaria verrucosa agar powder. Results The empirical findings demonstrate that a pretreatment using 7.5% NaOH and 0.040% HCl delivers optimal structural outcomes, recording a yield of 13.82%, gel strength reaching 1032.5 g/cm², viscosity of 18.32 cP, and reduced syneresis at 0.96%. Novelty Synergistic strong acid-base pretreatment replaces traditional weak acid steps, efficiently cleaving sulfate esters while preserving structural polysaccharide integrity. Implications These standardized parameters offer an efficient industrial approach to produce high-grade agar powder meeting commercial standard specifications. Key Findings Highlights Pretreatment with combined strong alkali and strong acid solutions significantly improves physical properties of agar powder. Increasing concentrations of sodium hydroxide and hydrochloric acid reduce syneresis while elevating viscosity and gel strength. The treatment using 7.5% alkali and 0.040% acid concentration yields the highest extraction recovery and optimal structural performance. Keywords : Agar Powder, Gracilaria Verrucosa, Acid-Base Pretreatment, Gel Strength, Extraction Yield]]>
