Resistant starch is known to be a beneficial food component. An efficient method for producing it with clearly defined dimensions is required to increase its texture and sensing properties.
In an article published in the journal Carbohydrate Polymers, a simple method was reported to synthesize homogeneous resistant starch nanoparticles (RSNP) using fractional crystallization of short-chain glucan derived from debranched starch.
What is Resistant Starch?
Resistant starch is a type of carbohydrate which resists digestion inside the small intestine and undergoes fermentation inside the large intestine. When the starch fibers undergo fermentation, they function as prebiotics and encourage the formation of good bacteria inside the gut. This leads to the formation of short-chain fatty acids, which help in providing better metabolism and colon health benefits.
Starch usually breaks down into glucose when it is digested. However, resistant starch does not undergo digestion inside the small intestine and therefore does not elevate glucose levels.
Resistant starch also offers various other benefits, including a greater sensation of fullness, prevention and treatment of constipation, reduced cholesterol levels, and decreased chances of colon cancer. Resistant starch causes less gas than other fibers because of its slower fermentation.
There is increasing focus on the regulation of starch digestion, particularly via an increase in the levels of resistant starch in starch-based consumables, because of the fear of chronic illnesses linked to quickly digesting starch.
Properties of Type 3 Resistant Starch
When gelatinized digestible starches are cooled down, they are converted into type 3 resistant starch via retrogradation. Type 3 resistant starch has gained popularity because of its thick and condensed structure and improved thermal stability compared with other kinds of resistant starch.
Nanoparticles derived from starch, like type 3 resistant starch nanoparticles, generally have dimensions of around a few hundred nanometers. Resistant starch nanoparticles are becoming increasingly appealing in the food sector as multifunctional additives with texture and sensing benefits over dietary fiber because they are healthy and affordable.
Production of Resistant Starch Nanoparticles
Thanks to its self-assembling characteristic without needing a solvent or chemical cross-linkages, short-chain glucan (SCG) has emerged as a viable platform for scalable manufacturing resistant starch nanoparticles.
Waxy maize starch (WMS) is better suited than regular maize starch for synthesizing resistant starch nanoparticles. This is due to the presence of big amylose molecules in normal maize starch, which may persist after the debranching event and impede the self-assembly of SCG.
Challenges in SCG Self-assembly
The thermodynamic mechanism of short-chain glucan self-assembly is highly sensitive to ambient factors, including temperature, pH, and the solvent.
If the thermodynamic factors are not regulated during self-assembly of short-chain glucan particles, it often leads to the creation of resistant starch nanoparticles with a highly non-uniform and aggregated arrangement. This may have a detrimental impact on the sensing properties of the nanoparticles when employed as a powder or colloidal dispersion in consumable items.
Such agglomeration can potentially restrict the practical uses of resistant starch nanoparticles in the food sector. Surfactants like chitosan and lecithin can inhibit resistant starch nanoparticle agglomeration through electrostatic repulsion and steric stabilization.
Surfactant usage, on the other hand, can negatively affect human health. Furthermore, the steric stabilization of polyelectrolytes is influenced by the pH of the reactant solution, which limits their effective usage.
A scalable manufacturing technique is needed that produces homogeneous and monodisperse resistant starch nanoparticles and does not require chemical alteration or steric stabilization.
Results of the Study
In this study, the team produced monodisperse and uniform resistant starch nanoparticles without stabilizing agents, chemical alterations, or cross-linkages.
The fabrication procedure was exclusively dictated by the self-assembling characteristic of SCG, which was prepared in an aqueous setting using enzymatically-debranched WMS.
The concentration of SCG in comparison with partially debranched amylopectin in the reaction mixture affected the shape and dimensions of the self-arranged nanoparticles. The SCG-rich reaction mixture formed uniform resistant starch nanoparticles having a small size distribution concentrated at roughly 150 nm.
The produced resistant starch nanoparticles were stable in acidic as well as alkaline conditions and possessed a negative charge on the surface. Certain temperature-triggered stimuli may be used to cause the self-assembly of the resistant starch nanoparticles into predefined nanoparticle shapes and dimensions without compromising fabrication output.
The concentration of resistant starch in RSNP was determined to be about 80 percent, which was unaffected by the consecutive cycles of the assembly/disassembly procedure.
The developed starch-based nanomaterial, with its distinct properties including significant resistant starch concentration, safety, low cost, and excellent colloid stability, shows good prospects in several areas like cosmetic, pharmaceutical, and food industries.
Adra, H. J., Zhi, J., Luo, K., & Kim, Y.-R. (2022). Facile preparation of highly uniform type 3 resistant starch nanoparticles. Carbohydrate Polymers. Available at: https://doi.org/10.1016/j.carbpol.2022.119842