Globally, up to 40% of food is wasted, resulting in the loss of valuable nutrients and resources. Fruit and vegetable processing alone generates around 50% by-product waste, largely composed of plant cell wall polysaccharides such as pectin. Among pectic components, rhamnogalacturonan-I (RG-I) is particularly underexplored due to the difficulty of isolating it in its native, branched form. Yet, RG-I’s complex structure and its potential functional properties—such as gelling, emulsifying, and prebiotic activity—suggest a high value for food applications. Current extraction methods rely on harsh chemical or physical treatments that degrade RG-I, preventing both structural characterization and sustainable large-scale production.
RHAPPLE addresses this challenge by developing a biotechnological route for the selective isolation of intact RG-I from fruit and vegetable side-streams using a fermentative approach. The project uses the yeast Kluyveromyces (K.) lactis, which can be genetically modified to secrete specific enzymes that degrade other plant cell wall polysaccharides while leaving RG-I intact. This strategy replaces chemical extraction with a mild, low-resource, and scalable process.
The project’s objectives are to (1) establish K. lactis as a biotechnological platform for RG-I isolation, (2) engineer strains producing targeted enzyme sets, and (3) elucidate structure–function relationships of the isolated RG-I. By creating a sustainable process for producing high-quality RG-I and mapping its functional properties, RHAPPLE will unlock the potential of this polysaccharide as a multifunctional ingredient. The expected impact includes reducing food waste, promoting circular bioeconomy approaches, and fostering innovation in the European food and biotechnology sectors.
