Enhancement of nutritional and functional properties of sacha inchi meal by solid-state fermentation

• Solid-state fermentation (SSF) improved nutritive value of sacha inchi meal (SM). • SSF enhanced the total phenolic content and antioxidant activity of SM. • Protease, α-amylase and β- glucosidase play important roles in phenolic release. • The compositions of phenolic compounds increased after the fermentation. • Fermentation increased lysine and alanine contents, enhancing protein quality This study aimed to enhance the nutritional and functional properties of sacha inchi meal (SM) through solid-state fermentation (SSF). SM was fermented using different fermentation systems: Bacillus subtilis at 35°C for 48 h (BSM), Rhizopus oligosporus at 25°C for 24 h (RSM), and Lactobacillus acidophilus at 35°C for 72 h (LSM), with unfermented SM (USM) used as a control. Fermentation significantly increased total phenolic content (TPC), with BSM and RSM showing 8.2- and 3.0-fold increases, respectively, compared to USM, while TPC in LSM remained comparable to that of USM (1.0-fold). HPLC analysis confirmed significant increases of eight phenolic compounds in all fermented samples compared to USM ( p ≤ 0.05). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis -3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activities were enhanced in BSM, RSM, and LSM relative to USM, ranging 25.20-73.84% and 69.56-81.23%, respectively. Enhanced antioxidant activities, particularly in BSM and RSM, correlated positively with increased TPC and enzymatic activities of protease, α-amylase, and β -glucosidase. The SEM surface morphologies of SM powders showed degradation of the cell wall structure caused by microbial enzymatic hydrolysis, which led to the release of phenolics. Although amino acid compositions did not significantly differ ( p > 0.05), lysine and alanine increased ( p ≤ 0.05), improving the essential amino acid index. All samples exhibited strong ACE inhibitory activity (78.75-81.10%, p > 0.05), indicating antihypertensive potential. These findings highlight SSF as an effective method for enhancing the quality of SM, supporting its potential in functional food applications.