Storage-Induced Changes in Raw vs. Commercial Spirulina: A Molecular, Nutritional and Microbial Perspective

Abstract

Introduction: Spirulina, a nutrient-rich cyanobacterium, is widely used in functional foods and nutraceuticals, but its stability during storage—especially in raw form—remains a critical challenge. Today, Spirulina is widely incorporated into functional foods, nutraceuticals, and pharmaceuticals, typically in a processed form. However, raw Spirulina, which refers to the unprocessed biomass prior to drying or formulation, presents distinct challenges in terms of stability and safety. Aim: This study elucidates the molecular, nutritional, and microbial changes that occur in raw and commercial Spirulina during storage under varying conditions. Materials and Methods: This study compared molecular, nutritional, and microbial changes in raw and commercial Spirulina stored under ambient, refrigerated, and vacuum-sealed conditions over 42 days. FTIR spectroscopy was used for molecular profiling; protein, lipid, carbohydrate, and antioxidant content were measured via standard assays; microbial dynamics were analyzed through culture methods and VITEK 2 identification. Results and Discussion: FTIR analysis showed marked molecular degradation in raw Spirulina stored at ambient temperature, with reduced spectral intensity for proteins, lipids, and carbohydrates. Commercial Spirulina, particularly under refrigerated and vacuum conditions, retained higher biochemical stability. Nutritional assays confirmed greater retention of proteins (up to 85%), lipids, and carbohydrates in commercial samples. DPPH assay showed antioxidant activity declined in all conditions but was best preserved under refrigeration. Microbial analysis revealed higher bacterial loads in raw Spirulina (up to 6.8 log CFU/g), with dominant species including Pseudomonas, Bacillus, and Enterobacter. Commercial formulations exhibited significantly lower contamination. Conclusion: Storage method significantly influences Spirulina quality, with refrigeration and vacuum sealing proving effective in preserving functional and microbial stability. These findings offer actionable guidance for optimising Spirulina storage strategies to extend shelf life and maintain product quality in both raw and commercial forms. They also provide a scientific basis for informing consumer storage practices and support the development of standardised industry protocols to enhance product safety and nutritional retention.