Phenolic-Bioactivity Connectivity Networks Reveal How Lactic Fermentation Restructures Function in Murta Berry Juice

Area of Science:

• Food Science and Technology
• Microbiology
• Biochemistry

Background:

• Lactic fermentation significantly alters polyphenol profiles in plant-based foods.
• The functional consequences of these phenolic changes, particularly across different extractable (EP) and hydrolyzable (HP) fractions, are not fully understood.
• Murta (Ugni molinae) juice is a rich source of bioactive polyphenols.

Purpose of the Study:

• To investigate how lactic fermentation impacts the phenolic composition and bioactivity of murta juice.
• To correlate specific phenolic compounds with functional outcomes, including antimicrobial activity, enzyme inhibition, and oxidative stress modulation.
• To establish a framework for designing fermentation strategies to achieve targeted bioactivity.

Main Methods:

• Fermentation of murta juice using Lactobacillus acidophilus, Lactiplantibacillus plantarum, and a coculture under optimized GDF and SAW strategies.
• Comprehensive phenolic profiling using advanced analytical techniques.
• Assessment of antimicrobial activity against E. coli, S. enterica, and S. aureus.
• Enzyme inhibition assays for α-amylase, α-glucosidase, and DPP-IV.
• Evaluation of oxidative stress modulation in Caco-2 cells.
• Application of a phenolic-bioactivity connectivity framework and bipartite correlation network analysis.

Main Results:

• Principal component analysis clearly distinguished fermented from unfermented samples, with coculture fermentation (MIX-GDF) showing the most significant compositional divergence.
• Extractable polyphenol (EP) fractions were primarily responsible for antimicrobial effects and α-glucosidase inhibition.
• Hydrolyzable polyphenol (HP) fractions were key contributors to DPP-IV inhibition and modulation of intracellular reactive oxygen species (ROS).
• A structured correlation network revealed distinct mechanisms: specific flavonoid-bioactivity links for enzyme inhibition and collective interactions for antimicrobial activity.

Conclusions:

• Fermentation-induced phenolic remodeling in murta juice leads to structured and predictable functional outcomes.
• The study provides a rational basis for optimizing fermentation processes to tailor specific bioactivity profiles.
• Understanding the differential contributions of EP and HP fractions is crucial for harnessing the full functional potential of fermented plant matrices.