Surface modification and protein engineering to enhance monellin stability for food applications

Overview

This research program focuses on enhancing the stability and functionality of monellin, a naturally sweet protein, through two complementary approaches: surface modification via carbohydrate conjugation and targeted protein engineering. Monellin offers significant potential as a natural, low-calorie sweetener, but its practical use in food applications is limited by thermal instability and poor solubility at low pH. By addressing these limitations, the program aims to produce a more robust sweetener ingredient suitable for a wider range of food and beverage formulations.

The value proposition centers on delivering a naturally derived sweetener with improved shelf-life and performance characteristics, addressing key barriers that currently restrict the commercial use of protein-based sweeteners. The approach combines well-established food chemistry principles with modern computational protein design tools to create synergistic improvements in stability.

Technical specifications

Surface modification approach:

• Conjugation of monellin with small carbohydrates via the Maillard reaction
• Use of inulin (degree of polymerization under 10) to achieve higher solubility with minimal viscosity
• Glycation with glucose to improve solubility and prevent aggregation
• Incorporation of galacturonic acid to introduce negative charges that enhance stability and sweetness response

Protein engineering approach:

• Site-directed mutagenesis to alter amino acid sequence
• Bioinformatics-informed mutation design using computational tools such as AlphaFold and ASR (ancestral sequence reconstruction)
• Recombinant protein expression in bacterial systems
• Purification using ion exchange, size exclusion, and reverse phase chromatography

Characterization methods:

• Conjugate size analysis via light scattering
• Molecular weight determination through electrophoresis and mass spectrometry
• Native folding assessment using circular dichroism
• Thermal stability measurement via fluorescence and calorimetry
• Solubility and aggregation profiling through turbidimetry
• Sensory evaluation for sweetness assessment

Technology readiness level

This research is at an early-to-mid stage of development. The underlying chemistry of protein-carbohydrate conjugation via the Maillard reaction is well-established in food science, providing a strong foundation. However, the specific application to monellin represents novel work. The research team at the University of British Columbia brings complementary expertise in food protein biophysics and carbohydrate chemistry, along with established methodologies for biopolymer characterization and sensory evaluation. Future validation will focus on optimizing conjugation conditions, characterizing modified proteins, and assessing sweetness through sensory testing. The technology is currently at the laboratory research and proof-of-concept stage, with further development needed before commercial application.