Lactic Acid Bacterial Culture Selection for Orange Pomace Fermentation and Its Potential Use in Functional Orange Juice

The main goal of this study is to improve the bioactivity of citrus pomace by subjecting it to solid-state fermentation by Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus plantarum over varying periods of time. The viability of Lactobacillus, as well as the total phenolic content (TPC) and total antioxidant capacity (TAC) values of orange pomace (OP), varied depending on the Lactobacillus species and fermentation period. The incorporation of pomace into orange juice samples at a ratio of 5% considerably enhanced the viability of probiotics. The TPC and TAC of orange juice samples were reduced after fermentation. The addition of orange pomace to orange juice significantly increased prostaglandin H2 and improved antioxidant capacity with more pronounced effects at increased pomace concentrations. After postfermentation with L. plantarum, key bioactive compounds such as corynoxeine and phenolics were upregulated, while picroside III and allocryptopine levels were decreased. On the other hand, metabolomics analysis revealed significant changes after fermentation in amino acid, sphingolipid, and fatty acid metabolism and the synthesis of secondary metabolites improving the nutritional profile and bioactivity of fermented orange juice. These findings highlight the potential of pomace addition and fermentation to improve the health benefits and quality of orange juice products. Therefore, the combined use of fermentation and fortification with OP could be a promising approach to creating new functional foods and promoting the use of edible food waste and byproducts.