Strategy comparison for purifying phycocyanin from microplastic-contaminated Spirulina platensis: A dual evaluation...

Microplastic contamination in Spirulina platensis (S. platensis)-derived foods poses significant safety risks, yet previous phycocyanin purification processes lack targeted microplastic removal strategies. This study developed integrated purification strategies, including activated carbon adsorption (AC), liquid biphasic flotation, ammonium sulfate precipitation (AS), and their combinations, to recover phycocyanin from microplastic-contaminated S. platensis. The effectiveness of purification processes wascompared in terms of yield, purity (A₆₂₀/A₂₈₀), microplastic residual rates, and processing time. Microplastic residues were quantified using Raman imaging and Py-GC/MS. The results indicated that the AC-AS and AS-AS methods effectively reduced the residues of polyethylene, polypropylene, nylon-6, and polyethylene terephthalate to 2.81 % and 2.58 %, respectively, through density gradient separation. Moreover, both processes achieved food-grade purity (∼1.3) and higher yield (50.25-50.64 mg/g), outperforming other approaches. Considering efficiency and time cost, the AC-AS method was found to be optimal. This work provides strategies for producing food-grade phycocyanin and mitigating microplastic contamination in the food industry.