Supplementation of date palm (Phoenix dactylifera L.) residue for growth and lactic acid production of probiotic bacterial Lactobacillus spp.

Date palm is an age-old cultivated plant that thrives in tropical and subtropical regions. The date palm is a bountiful source of carbohydrates, encompassing sucrose, glucose, and fructose and proteins. The date industry generates a significant volume of unused by-products. Dates offer a diverse range of by-products beyond the agri-food sector. LAB have garnered extensive utilisation across diverse food sectors, spanning meat, vegetables, beverages, dairy products, and other fermented foods. In the quest for establishing a new large-scale fermentation process for lactic acid there has been a concerted effort to utilise more cost-effective medium components. In the present work, date palm residue (DPR) derived from date palm fruit, after sugar extraction, was incorporated into MRS. The fermentation process was executed through two distinct fermentation systems. Initially, experiments were conducted in flasks. Afterward, the optimal conditions for bacterial growth were determined, and the experiment was carried out using a bioreactor. DPR supported the probiotic Lactobacillus spp. growth especially after 48 h incubation. The prebiotic effect of DPR on Lactobacillus spp. was reported. An increase in the total number of bacterial populations was observed in response to the addition the DPR until 48 h. Specifically, the supplementing DPR at a concentration of 1.5% in batch fermentation enhanced the growth and lactic acid production of Lactobacillus casei . This study suggests that DPR could potentially function as an economical prebiotic source and could be seamlessly incorporated as a functional food ingredient, thereby transforming a waste product into an economically sustainable food substrate.