Carotenoids are tetraterpene compounds acting as precursors to vitamin A, with functions that include protecting eyesight, enhancing immunity, promoting cell growth and differentiation, and providing antioxidative benefits. Lycopene, β-carotene, and astaxanthin are particularly critical for health and have diverse applications in food, health products, and medicine. However, natural carotenoids are encased within cell structures, necessitating mechanical methods to disrupt the cell wall for their extraction and purification—a process often influenced by environmental conditions. Thus, improving the efficiency of carotenoid extraction from natural resources is of great interest. This review delves into the research progress made on the extraction processes, structures, and biological functions of carotenoids, focusing on lycopene, β-carotene, and astaxanthin. Traditional extraction methods primarily involve organic solvent-assisted mechanical crushing. With deeper research and technological advancements, more environmentally friendly solvents, advanced machinery, and suitable methods are being employed to enhance the extraction and purification of carotenoids. These improvements have significantly increased extraction efficiency, reduced preparation time, and lowered production costs, laying the groundwork for new carotenoid product developments.

Phycoerythrin and polysaccharides have significant commercial value in medicine, cosmetics, and food industries due to their excellent bioactive functions. To maximize the production of biomass, phycoerythrin, and polysaccharides in Porphyridium purpureum, culture media were supplemented with calcium gluconate (CG), magnesium gluconate (MG) and polypeptides (BT), and their optimal amounts were determined using the response surface methodology (RSM) based on three single-factor experiments. The optimal concentrations of CG, MG, and BT were determined to be 4, 12, and 2 g L⁻¹, respectively. The RSM-based models indicated that biomass and phycoerythrin production were significantly affected only by MG and BT, respectively. However, polysaccharide production was significantly affected by the interactions between CG and BT and those between MG and BT, with no significant effect from BT alone. Using the optimized culture conditions, the maximum biomass (5.97 g L⁻¹), phycoerythrin (102.95 mg L⁻¹), and polysaccharide (1.42 g L⁻¹) concentrations met and even surpassed the model-predicted maximums. After optimization, biomass, phycoerythrin, and polysaccharides concentrations increased by 132.3%, 27.97%, and 136.67%, respectively, compared to the control. Overall, this study establishes a strong foundation for the highly efficient production of phycoerythrin and polysaccharides using P. purpureum.

The gut microbiota plays important functions in human health and influences immune responses, metabolic processes, and several physiological activities. The modulation of the gut microbiota through dietary interventions has emerged as a promising approach, leading to significant interest in the development of functional foods that provide health benefits. In this context, our study investigated the effects of raspberry juice fermented by Limosilactobacillus fermentum FUA033 on the structure and metabolism of the gut microbiota. We performed 16S rRNA gene sequencing and nontargeted metabolomics analyses to evaluate changes in the microbial composition and metabolite profiles resulting from fermentation. Our findings revealed that fermented raspberry juice considerably increased the gut microbial diversity and promoted the abundance of beneficial genera. Fermentation substantially increased the production of short-chain fatty acids, such as acetate and butyrate, which increased from 30.09 ± 5.23 mmol/L to 43.07 ± 3.31 mmol/L, and from 7.72 ± 1.72 mmol/L to 15.01 ± 1.26 mmol/L, respectively. Metabolomic analyses also showed significant enhancements in amino acid metabolism pathways, particularly those involving tyrosine, arginine, and proline. These results highlight the potential of fermented raspberry juice as a functional food to improve gut health and metabolic functions.