Effect of Solid-State Lactic Acid Fermentation on the Antimicrobial Activity and Biochemical Properties of Argan Press Cake

Argan oil production generates large amounts of press cake that remain underexploited despite their potential as a functional ingredient due to their high protein and fiber content. This study aimed to evaluate the effects of solid-state fermentation of argan press cake (APC) for 24 h and 48 h at 30 °C using Pediococcus pentosaceus LUHS183, Pediococcus acidilactici LUHS29, and Lactiplantibacillus plantarum LUHS135. The effects of fermentation were assessed by determining pH, viable counts of lactic acid bacteria (LAB), free amino acid (FAA) profiles, including γ-aminobutyric acid, biogenic amine (BA) concentrations, fatty acid (FA) and volatile compound (VC) profiles. Additionally, antimicrobial activity was evaluated against 15 pathogenic strains. Fermented samples showed LAB growth, lower pH values than the control, and antimicrobial activity against several of the tested strains. FAA profiles varied among the samples. Only two of the eight BA analyzed, namely spermidine and spermine, were detected in all APC samples. Their concentrations in the control were 29.4 ± 2.29 mg/kg and 29.7 ± 3.66 mg/kg, respectively. Unfermented and fermented samples shared the same predominant FA. Overall, the observed biochemical profiles and antimicrobial activity support further investigation of fermented APC as a potential value-added ingredient in food applications.