Introduction to Porous Starch (PS)

Few pores have been reported in native starch. Artificial pores can be created using many approaches. For example, a portion of the macromolecules within a granule can be hydrolyzed by enzymes or acids to low molecular fragments, and pores are formed when these hydrolyzed products dissolve. Another approach involves starch chains in a microemulsion which are cross-linked to form microspheres, and pores are present in some of the resulting products. In addition, starch gels can exhibit a porous structure when treated with freeze-thaw processes. In recent years, a solvent exchange method and other methods have been used to produce porous starch (PS) or to enhance the pore-forming efficiency.

PS contains abundant pores from the surface to the center of the granules, which increase the specific surface area, and PS acts as an excellent natural absorbent and has been widely used in food, pharmaceuticals, agriculture, cosmetics, pulp and paper, and other industries. There is a growing interest in exploiting the properties of PS in various food and non-food areas. In the food industry, PSs are used as colorants, spices, flavorings, sweeteners, and carriers and to protect sensitive elements such as oils, minerals, vitamins, bioactive lipids, and food pigments such as β-carotene and lycopene which are sensitive to light, oxidation, or high temperature.

The structure and properties of PS have been determined by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and rheometry.

Starch is a natural polysaccharide and is an important energy source for humans, and native and unmodified starch has little industrial applicability. The interesting morphology of PS has attracted considerable attention in industrial applications, such as in food, pharmaceuticals, agriculture, cosmetics, pulp and paper, and other industries. PS can be obtained by physical, chemical, and biological methods, of which ultrasonic and enzyme treatments have mainly been used to produce PS.

Nowadays, starch is widely used as an abundant, renewable, inexpensive, biodegradable, and environmentally friendly biopolymer. However, the application of starch is limited by its naturally low surface area and pore volume. Thus, after physical, chemical, or biological modification, PS, with unique structures such as abundant micro-sized pores which extend from the surface of starch granules to the center, can be obtained and is widely used in the food, pharmaceuticals, agriculture, cosmetics, pulp and paper, and other industries. This chapter reviews the recent applications of PS and its functional properties in these applications.

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