Cellulase enzyme and citric acid in producing iodine-enriched agar powder from Gracilaria tenuistipitata

Seaweed is a valuable source of iodine, an essential micronutrient critical for thyroid function. However, conventional iodine fortification methods often result in nutrient loss and environmental issues, necessitating more sustainable alternatives. This study established an environmentally sustainable process to produce iodine-enriched agar powder from Gracilaria tenuistipitata C.F. Chang & B.-M. Xia, 1976, a red seaweed commonly cultivated in Vietnam. The production involved pretreatment, agar extraction, blending of functional ingredients, and organic iodine enrichment. Response Surface Methodology optimized critical factors, including enzyme concentration, citric acid usage, and iodine supplementation. The developed agar-based powder had a stable iodine content (7.42 mg/100 g), protein level (8.51%), and a firm, elastic gel texture. Utilizing MPB cellulase enzyme and citric acid improved the agar yield by ~ 20%, minimized the environmental impact, preserved bioactive compounds, and stabilized iodine. Optimal extraction conditions included cellulase (0.4–0.6%), temperature (45–50°C), and duration (36–48 h). The final optimal formulation combined agar, carrageenan, and gelatin (60:30:10). It was supplemented with 0.2% of sea grapes and 2.5% fermented red algae to significantly enhance iodine retention and sensory quality. Analytical tests (HPLC, UV-Vis) and sensory evaluation verified the product’s quality. The agar powder demonstrated excellent iodine stability and maintained sensory acceptability after six months of refrigeration storage. Integrating cellulase enzymatic treatment, citric acid refinement, and organic iodine enrichment effectively enhanced the nutritional value and addresses iodine deficiency in health-oriented functional foods.