A few days ago, researchers from Zhejiang Industrial and Commercial University published a research paper in the international journal Journal of Agricultural and Food Chemistry, saying that the team used controllable lipase-amylase to prepare new porous starch granules with digestion resistance.

According to reports, the surface of starch granules contains a large number of pores, pits, cracks and damaged areas, which can be used as the initial site of enzyme attack when producing porous starch. But cereal starches, such as wheat and corn starches, contain higher levels of lipids on their surface than tuber, root or legume starches. Although the lipid content of starch granules accounts for less than 1% of its total weight, the presence of the lipid layer will inhibit the ability of amylase to interact with the surface of starch granules, hinder the penetration of digestive enzymes into starch granules, and reduce the sensitivity of starch granules to enzymatic hydrolysis; on the other hand, the lipid layer will further affect the interaction between starch and water, inhibit the expansion of starch in water, thereby increasing the absorption rate of starch by the human body.

In this study, lipase was used to treat native starch granules to remove the outer lipid layer of the granules, exposing the starch molecules below the lipid-rich area on the surface, increasing the swelling of the starch granules in aqueous solution and making the peripheral area of the starch more loose, which is conducive to subsequent starch hydrolysis and the formation of large cavities. After that, the researchers adjusted the porosity and surface hydrophilicity of porous starch by optimizing the treatment of lipase and α-amylase, thus changing the pasting behavior, adsorption characteristics and digestibility of starch granules, making its pasting performance greatly reduced, the adsorption capacity of hydrophobic substances increased, and the digestibility decreased.

In addition, it is understood that the production cycle of porous starch produced by the general method is about 8-24 hours, and the production cycle can be reduced to 2-4 hours by this method, and the pore distribution of porous starch is more uniform, and it has good digestion resistance.

This study demonstrates that combined lipase-amylase treatment can be used to prepare porous starches that can be used to encapsulate, protect, and deliver hydrophobic bioactive substances such as oil-soluble vitamins, lipids, or nutraceuticals, as well as to produce foods that lower the glycemic index, with important implications for the design and manufacture of novel functional ingredients that have a wide range of applications.