Wall porosity in isolated cells from food plants: Implications for nutritional functionality

Area of Science:

• Plant cell biology
• Food science
• Biophysics

Background:

• Macronutrients in whole plant foods are contained within cells.
• Cell-wall porosity influences the passage of digestive enzymes, affecting nutrient metabolism.
• Understanding these barriers is crucial for optimizing nutrient absorption from plant-based diets.

Purpose of the Study:

• To investigate the impact of plant cell wall porosity on the diffusion of digestive enzyme mimics.
• To quantify the physical barrier effects of cell walls on nutrient accessibility.
• To provide insights for designing plant-based foods with enhanced nutritional value.

Main Methods:

• Used isolated plant cells from potato, red kidney bean, and banana.
• Employed fluorescently-labelled dextran (20-kDa and 70-kDa) and albumin as non-interacting size mimics of digestive enzymes.
• Quantified probe diffusion rates using fluorescence recovery after photobleaching (FRAP).

Main Results:

• A consistent reduction in diffusion rate (approximately 40%) was observed across plant cell walls compared to free diffusion.
• This reduction was attributed to the limiting porosity of the cell wall matrix.
• Demonstrated that physical barrier effects and non-catalytic binding limit enzyme access to intracellular macronutrients.

Conclusions:

• Plant cell walls act as a significant physical barrier, restricting the diffusion of digestive enzymes.
• The porosity of the cell wall matrix is a key factor limiting nutrient hydrolysis.
• Further understanding of cell wall structure can guide the development of foods with improved nutrient bioavailability from plant sources.