Banana Pseudostem By-Product: A Sustainable Source of Prebiotics and Protection for Probiotic Lactic Acid Bacteria Under Gastrointestinal Conditions

Agricultural by-products, such as banana pseudostems (BPS), present a sustainable solution for waste reduction and the recovery of valuable metabolites with biotechnological applications. This study investigated the potential of BPS as a substrate for bio-fermentation, specifically for the cultivation of lactic acid bacteria (LAB). Maçã cultivar BPSs (MBPS) and Nanica cultivar BPSs (NBPS) flour samples showed differences in carbohydrate composition, especially in resistant starch (16.7 and 2.7%), cellulose (27.0 and 52.4%), and hemicellulose (25.4 and 33.8%), respectively. Phenolic compound content in NBPS was higher than in MBPS (193.9 and 153.5 GAE/100 g, respectively). The BPS starches and flour were well assimilated by the probiotic LAB cultures. Limosilactobacillus fermentum SJRP30 and SJRP43 showed significant growth in media with gelatinized Maçã flour (GMF) and non-gelatinized Nanica flour (NGNF) BPS by-products (Log 9.18 and 9.75 CFU/mL, respectively), while Lacticaseibacillus rhamnosus GG exhibited the highest growth (Log 11.31 CFU/mL) in the medium with NGNF BPS by-products. The probiotic Lbs. casei SJRP146 and Lmb. fermentum SJRP30 and SJRP43 presented high enzymatic activity and the ability to assimilate D-xylose. Only Lactobacillus delbrueckii subsp. bulgaricus SJRP57 and SJRP49 were able to assimilate starch. Their prebiotic potential under in vitro gastrointestinal digestion was evidenced by promoting the selected probiotic bacteria’s protection and maintaining their viable cells after challenging conditions, likely associated with the BPS composition. Lab. delbrueckii subsp. bulgaricus SJRP57, Lacticaseibacillus casei SJRP145, and Lmb. fermentum SJRP43 performed similarly to the commercial strain Lbs. rhamnosus GG. These results demonstrate the feasibility of using cost-effective and abundant agricultural waste as a promising sustainable ingredient with potential prebiotic activity, via eco-friendly production methods that do not require chemical or enzymatic extraction.