Over the last years, the cyanobacteria Spirulina platensis (SP) has attracted special attention, as it possesses remarkable antioxidant activity and high amounts of bioactive compounds, such as phycocyanin, carotenoids and phenolics. Since Spirulina platensis biomass shows extremely high moisture content, dehydration is a crucial treatment step, which ensures the prolonged shelf life of the final product. However, drying affects drastically the qualitative characteristics of heat-sensitive foodstuffs with high nutritional value, such as SP. In this study, four different drying techniques, atmospheric drying (AD), freeze drying (FD), vacuum drying (VD) and accelerated solar drying (ASD), were examined and compared considering crucial parameters, i.e., moisture content reduction, change of structure, colour deterioration, pigment content and antioxidant activity. As shown from the obtained results, vacuum drying achieves faster moisture lowering and higher carotenoid content equal to 0.58 + 0.01 mg (g dry solids)⁻¹. On the other hand, atmospheric drying is efficient in preserving phycocyanin since its content was found equal to 9.65 + 0.19%dry weight, but in general cannot be industrially applied due to the long dehydration time. Finally, accelerated solar dried biomass showed the highest antioxidant activity (31.28 ± 0.90% dry weight) mainly due to the degradation products after heating at high temperatures and stress conditions.

Microalgae are being recognized as valuable sources of bioactive chemicals with important medical properties, attracting interest from multiple industries, such as food, feed, cosmetics, and medicines. This review study explores the extensive research on identifying important bioactive chemicals from microalgae, and choosing the best strains for nutraceutical manufacturing. It explores the most recent developments in recovery and formulation strategies for creating stable, high-purity, and quality end products for various industrial uses. This paper stresses the significance of using Life Cycle Analysis (LCA) as a strategic tool with which to improve the entire process. By incorporating LCA into decision-making processes, researchers and industry stakeholders can assess the environmental impact, cost-effectiveness, and sustainability of raw materials of several approaches. This comprehensive strategy will allow for the choosing of the most effective techniques, which in turn will promote sustainable practices for developing microalgae-based products. This review offers a detailed analysis of the bioactive compounds, strain selection methods, advanced processing techniques, and the incorporation of LCA. It will serve as a valuable resource for researchers and industry experts interested in utilizing microalgae for producing bioactive products with medicinal properties.

Worldwide, fruit processing industries reject high volumes of fruit waste, which represent rich sources of phenolic compounds and can be valorised through extraction, and then be reused for food, nutraceutical or cosmetic applications. In the present work, the optimisation of the recovery of phenolic compounds from apricot kernels and pulp, as well as peach pulp, through the green method of ultrasound and microwave assisted extraction (UMAE) is performed. Prior to extraction, a drying step of the pulps is conducted using freeze, vacuum and hot air drying. Except for the conventional extraction solvents of water and ethanol:water, a deep eutectic solvent (DES) formed by choline chloride/urea, and a natural deep eutectic solvent (NaDES) from choline chloride with lactic acid, are used, something that presentsecological benefits. With the aim of discovering the optimum extraction conditions, different values of the parameters of extraction time, utrasonic power and solvent/dry solid ratio are examined, and a mathematical model is developed to correlate them to the extraction yield (EY). The phenolic compounds and the antioxidant activity are determined through UV-Vis spectroscopy and High-Performance Liquid Chromatography (HPLC). The results of the study demonstrated that the most effective solvent in the extraction of apricot kernels is ethanol: water; DES is more efficient in the extraction of apricot pulp and NaDES in the extraction of peach pulps, reaching EYs of 25.65, 26.83 and 17.13%, respectively. In conclusion, both types of fruit waste are proved to have a significant content of valuable compounds, and the use of DES in fruit by-product extraction is effective and seems to be a promising alternative. Thus, the unexploited amounts of waste can be valorised through simple techniques and innovative solvents.