Comprehensive Investigation of Borde, an Ethiopian Traditional Cereal-Based Beverage: Characterization, Probiotic Strain Isolation, and Functional Beverage Development for Antiobesity
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Date
2025-01
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Addis Ababa University
Abstract
Ethiopia has a long-standing tradition of producing and consuming cereal-based beverages. One of the most popular traditional drinks is borde, which undergoes spontaneous fermentation using grains such as sorghum, maize, wheat, barley, millet, and their malts. However, this natural fermentation process poses challenges in terms of predictability, control, and quality. Undesirable outcomes like slow or incomplete fermentation, off flavors, short shelf life, and inconsistent quality can occur. Therefore, the main task of this work is to comprehensively study borde production. Various aspects including traditional processing techniques, microbiology, antioxidant properties, functionality, rheology, physicochemical characteristics, probiotic potential, identification of metabolites, and evaluation of effectiveness using the C. elegans model were investigated. Borde samples were collected from Addis Ababa (AA), Wolayita Sodo (WS), and Arba Minch (AM), Ethiopia, chosen based on their relevance to production, accessibility, and suitability for sample collection. The average physicochemical parameters of the borde samples included total acidity (TA) of 0.63 (g/100g), alcohol content of 3.26 %, pH of 4.04 and electrical conductivity of 0.78 ms/cm. The early stages of fermentation exhibited prevalence of enterobacteriaceae and aerobic mesophilic bacteria. Towards the end of fermentation, yeast and LAB dominated the microbiological profile of all borde samples. Antioxidant activities, assessed through DPPH and ABTS values, ranged between 51.5–64.6% and 47.4–62.9.1%, respectively. The average value of α-glucosidase and pancreatic lipase inhibition for borde samples were ranged from 36.56 – 43.23 % and 31.08 – 40.19 %, respectively. Rheological investigations indicated pseudoplastic fluid behavior, as evidenced by the decreasing viscosity values with shear rate. Eleven LAB and thirteen yeast strains were selected based on their bile salt hydrolase (BSH) activity and evaluate their cholesterol lowering ability and antioxidant activities. The results showed that LAB strains exhibited a strong potential to lower cholesterol (85-90%), while yeast strains showed the highest cholesterol removal (82-89%). All strains demonstrated strong antioxidant activity and survived simulated gastrointestinal tract (GIT) conditions. LAB and yeast isolates were selected as the most promising probiotics based on their ability to resist simulated GIT environments. Safety evaluation revealed that none of the strains exhibited undesirable hemolytic activity or mucin hydrolysis. LAB strains were not resistant to most tested antibiotics except for vancomycin, gentamycin, and streptomycin, whereas yeast isolates were resistant to all antibiotics. The LAB strains were identified as Pediococcus acidilactici, while, yeast isolates were identified as Saccharomyces cerevisiae, and Pichia cecembensis. The probiotic strains, Pediococcus acidilactici WS07 and Saccharomyces cerevisiae AM18 was used singly and in co-culture to ferment a cereal-based substrates. The viability of every tested strain remained higher than 7 log CFU/mL, satisfying the requirements suggested for probiotic food items. The formation of organic acids is what caused the pH to decrease from roughly 6.6 to 3.8, yet this had no effect on the viability of the microorganisms. A total of 25 volatile substances, such as aldehydes, alcohols, esters, acids, ketones, and other substances, were found. The extracts from fermented cereals were comprehensively assessed for antioxidant activity, pancreatic lipase and α-glucosidase inhibition, UHPLC-Q-TOF-MS/MS metabolite identification, and in vivo efficacy using the C. elegans model. The findings highlight the remarkable improvements in metabolites and fat-reducing effects of the extracts from fermented cereals, presenting encouraging avenues for anti-obesity research. Notably, the fermented sorghum extracts improved lipase (88.23%), α-glucosidase (85.62%), DPPH (71.86%), and ABTS (59.92%) inhibitory activities compared to unfermented sorghum extract. All fermented extracts displayed strong antioxidant properties, as shown by increased DPPH (67.77–71.86%) and ABTS (59.91–65.49%) scavenging activities. The study further unveiled substantial increases in total polyphenols, flavonoid contents, and individual polyphenols following fermentation. Untargeted metabolite profiling using UHPLC-Q-TOF-MS/MS demonstrated significant changes in the metabolite composition of fermented samples. Additionally, supplementing C. elegans with fermented extracts resulted in an extended lifespan, reduced lipid content, and diminished triglycerides, indicating potential health benefits. This research emphasizes the potential of P. acidilactici WS07-fermented sorghum and sorghum-maize extracts as valuable resources for the development of functional foods with enhanced antioxidant and anti-obesity properties. The study contributes valuable insights into the bioconversion of cereals through microbial fermentation, showcasing their potential for promoting health and combating obesity.
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Keywords
Borde, Pediococcus, Saccharomyces, antioxidant, antiobesity, physicochemical, rheology