Effect of Enzyme Supplementation and Fermentation Time on the Nutritional Composition of Olive Pomace Fermented with Lactobacillus acidophilus

Nutritional changes of olive pomace during solid-state fermentation by Lactobacillus acidophilus with different fermentation times and enzyme supplementation were investigated in this study. A 3 x 2 factorial design was performed to investigate the effect of fermentation time (3, 5, and 7 days) and enzyme supplementation (with or without) with five replicates in each group. Before fermentation, olive pomace was ground to a 1 mm particle size and sterilized after mixing with distilled water at 121 °C for 15 min. The enzyme mixture (phytase, xylanase, and beta-glucanase) sterilized by UV lights was added to half of the fermentation medium. The olive pomace was inoculated with L. acidophilus and incubated at 30 °C for 3, 5, and 7 days. Solid-state fermentation using L. acidophilus increased (P<0.001) the crude protein and crude fiber content, decreased (P=0.007) the ether extract content, and had no influence (P=0.094) on the ash content of olive pomace. The highest crude protein content was observed (P<0.001) in fermented olive pomace for 3 days with enzyme and for 5 days without enzyme supplementation. Fermented olive pomace for 7 days without enzymes had the lowest (P<0.001) crude fiber content. The highest ether extract level was found (P=0.001) in fermented olive pomace for 3 days with or without enzyme. Enzyme supplementation caused (P=0.001) higher ash level in fermented olive pomace. Besides, a linear increase was observed (P=0.024) in ash content with increased fermentation time. The highest ash level in fermented olive pomace was found (P=0.048) at 7 days of fermentation. The result showed that L. acidophilus improved the nutritional composition of olive pomace in solid-state fermentation. Considering the highest crude protein content and relatively lower crude fiber and higher ether extract content, 3 days of fermentation with enzyme is the most effective fermentation conditions with L. acidophilus for olive pomace.