Optimization of fermentation process of pineapple peel residue for astaxanthin production with composite strains

To determine the optimal process for producing astaxanthin by pineapple residues fermentation with composite strains, using pineapple peel residues as raw materials and using Lactiplantibacillus plantarum CG1, Saccharomyces cerevisiae FP-8, and Phaffia rhodozyma XYV3 as fermentation strains, with astaxanthin yield and P. rhodozyma biomass as evaluation indicators, the fermentation conditions were optimized by single- factor tests and response surface methodology. The results revealed that the optimal fermentation conditions were as follows: S. cerevisiae FP-8 and L. plantarum CG1 ratio 2:1, inoculum 10%, P. rhodozyma addition 8% after fermentation for 51 h, followed by aerobic fermentation in a shaker at 22.5 ℃ and 180 r/min for 96 h. Under these optimized parameters, the astaxanthin yield reached 3.12 mg/L, which increased 67.47% compared to P. rhodozyma single-strain fermentation (1.86 mg/L). The results indicated that the combined-strain fermentation of S. cerevisiae, L. plantarum, and P. rhodozyma was a more efficient approach than the single-strain fermentation of P. rhodozyma, which could significantly enhance astaxanthin production.