Determination of the presence of microplastic (MP) in marketed Spirulina platensis products

Spirulina platensis is a blue-green algae that is produced and marketed as a health supplement due to its rich nutritional content. Since microplastic (MP) contamination has been detected in many foods and threatens health, there is a need to investigate microplastic contamination in commercially sold Spirulina platensis products and this research has not been done before. In this study, 29 Spirulina samples were obtained from different brands and origins in different packages and analyzed for MP using microscopic and μ-Raman techniques. C-phycocyanin levels were analyzed to confirm Spirulina content and for comparison with MP content. In total, 251 MP-like particles were observed, 26 of the 29 packaged Spirulina samples were identified by visual inspection as potentially containing MP, and 35 of these particles were confirmed to be indeed MP. 73% of the particles analyzed were actual MPs. The average MP content was estimated at 13.77 ± 2.45 MP/100 g dry weight (k.a.). When the amount of MPs in Spirulina products in powder, capsule/tablet form were compared, no statistically significant difference was found between the products. Of the MPs examined, 38.3% were particles and 61.7% were fibers, with particle sizes ranging from 0.07 to 2.15 mm and fiber sizes ranging from 0.19 to 5.691 mm. The color distribution of MPs in spirulina samples was mainly navy blue (33.20%), black (25.51%) and blue (19.43%). Other colors were white (10.93%), red (2.83%), purple (2.43%), gray (2.0%), brown (1.21%), green (1.62%), yellow (0.4%) and transparent (0.4%). µ-Raman analysis identified 10 different synthetic polymers and celluloses, the most common being polypropylene (31.6%) and polystyrene (8.3%). No significant correlation was found between the amounts of C-phycocyanin and MP. The presence of MP is thought to be due to product packaging and processing stages. It is of great importance to identify potential sources of MP in spirulina products and to evaluate the possible effects on human health.