Differences in odor-active compounds and non-volatile precursors between spray-dried and freeze-dried Spirulina platensis revealed by GC×GC-TOFMS-O and UPLC-MS/MS

The effects of freeze-drying and spray-drying on odorants and precursors in Spirulina platensis (Sp) cultivated in different environments (gj: glass jar; rp: raceway pond; cp: circular pond) were investigated. Ninety-four odorants were identified, and hexanal, (Z)-4-decenal, (E, E)-2,4-decadienal, β-cyclocitral, β-ionone, dimethyl trisulfide exhibited higher flavor dilution factors (≥ 81). Spray-drying increased pyrazines and terpenoids formation, enhancing roasted and seaweed-like odors, whereas freeze-drying retained higher levels of aldehydes and acids, causing fishy and rancid odors. Freeze-dried Sp-gj was enriched in dimethyl sulfur, whereas spray-dried Sp-gj, Sp-rp, and Sp-cp were enriched in dimethyl trisulfide, emphasizing the influence of cultivar and drying on sulfide formation. Spray-drying converted β-carotene into β-cyclocitral and β-ionone and methionine into methional and dimethyl trisulfide, elucidating the mechanisms responsible for seaweed-like and fishy odors for Sp. These findings underscore the critical role of cultivar and drying in modulating S. platensis odor, providing valuable insights for optimizing its sensory attributes.