Optimization of Hydrolysis and Fermentation of <i>Spirulina Platensis</i> Proteins for Production of Amino Nitrogen-Enriched Seasoning

Abstract Spirulina contains high protein content, essential amino acids, and bioactive compounds; however, their food products are often limited due to great reliance on costly imports and underdeveloped local production. To address this gap, the transformation of Spirulina protein into bioavailable and flavorful hydrolysates is necessary. Here, we investigated key parameters (e.g., protease activity, hydrolysis temperature, and pH) on the degree of enzymatic hydrolysis. Fermentation conditions, including salt concentration (5–25%), incubation temperature (30–70°C), and duration (2–14 days) were also tested on the amino nitrogen content for seasoning sauce production. Using response surface methodology, optimal hydrolysis conditions were determined as 80.46 UI/g protease activity, 44°C, and pH 8.39, yielding a maximum degree of hydrolysis of 50.75% after 2 hours. The resulting hydrolysate was fermented under controlled conditions (20% NaCl, 30°C, 6 days) and produced a seasoning sauce with an amino nitrogen content of 15.45 g/L. Fermentation parameters, e.g., time, temperature, and salt concentration, had significant effects on product quality. Thus, enzymatic hydrolysis followed by controlled fermentation was effective for enhancing the nutritional and functional value of Spirulina proteins. This integrated approach offers a viable pathway for developing high-value algae-based seasonings, and can bring an innovative and sustainable food bioprocessing strategy.