Degradation of pigments in Limnospira platensis extracts

Limnospira platensis, commonly known as spirulina, holds promise for application as a food ingredient and nutraceutical due to its rich protein and antioxidant content, including chlorophylls, carotenoids and phycocyanin. Despite its potential, the vibrant colour poses a challenge for consumer acceptance, hampering the marketability of spirulina-based products. To overcome this, innovative strategies are needed to effectively reduce colour while preserving its nutritional value.

This study sought to compare the impact of endogenous enzymatic and exogenous horseradish peroxidase (HRP)-mediated processes on colour degradation in spirulina extracts. Intrinsic and extrinsic colour degradation experiments were conducted, with and without hydrogen peroxide (H₂O₂) and 4-hydroxybenzenesulfonic acid (PSA) as co-substrate and analysed using UV-visible spectroscopy. Specifically, the absorbance changes were monitored at 440 and 677 nm, corresponding to chlorophylls a and b, the predominant pigments in spirulina extracts. The degradation of spirulina extracts exhibited a distinct two-stage pattern. The initial stage, observed within the first hour, displayed a rapid decrease in absorbance, followed by a slower decline in the subsequent stage. In the presence of H₂O₂, intrinsic degradation caused a gradual absorbance reduction of less than 30% after 24 h. Importantly, the introduction of exogenous factors, including HRP and PSA, resulted in a remarkable 40% absorbance decrease within less than 30 min.

This substantial enhancement in decoloration efficiency, surpassing the intrinsic metabolic activity, underscores the potential of extrinsic enzymatic approaches. These findings hold promise for addressing the challenge of spirulina extract colouration in products, potentially enabling improved market acceptance and viability. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.