Unveiling the biomass conversion potential: study on drying methods’ influence on polyphenols and linked antioxidant activities in euryhaline microalgal biomass with AI-predicted drying kinetics

This study investigates a salt-tolerant microalga, Chlorosarcinopsis eremi (GenBank accession no. MN796425) to assess its polyphenol potential, the effect of drying methods, viz., freeze drying (FD), oven drying (OD), and shade drying (SD) on polyphenols, antioxidative activities, analysis of drying kinetics, and effective moisture diffusivity (Deff). A comparison between mathematical and artificial neural network (ANN) modeling to predict moisture ratio (MR) was also studied. OD and SD decrease free polyphenols compared to FD (P < 0.05). OD preserved bound phenols and exhibited the highest DPPH and superoxide scavenging activities, correspondingly depicted by the highest positive correlation (r = 0.98 and r = 0.95). FD showed the highest ferric reducing and total reducing powers due to high free phenols and is highly positively correlated. Nitric oxide scavenging activities showed a high positive correlation with total flavonoids (r = 0.99). Hydroxyl radical scavenging activity increased by the number of polyphenols and strongly correlated with free-form phenols (r = 0.92) Ferrous ion chelating activity correlated with total phenols and flavonoids (r = 0.99), highest in FD. OD showed the highest rate of drying, followed by FD and SD. Deff values were in the expected range for agricultural materials. The Modified Page model provided the best fit for experimental data in all three drying methods. ANN proved more accurate in predicting drying kinetics for all three drying methods in comparison to mathematical modeling with R2 = 0.9992. Cholorosarcinopsis showed potential as a polyphenol-rich source for nutraceuticals and pharmaceuticals. OD emphasizes bound form, while FD captures total polyphenol content. Specific drying methods can be targeted for desired antioxidant activity.