The influence of particle size on the structure, physicochemical properties, and sensory quality of insoluble dietary fiber in lotus leaves
Dietary fiber has the effects of regulating blood sugar, lowering blood lipids, preventing obesity, and regulating gut microbiota, and has become a favored functional food ingredient for consumers. Dietary fiber extracted from agricultural and sideline products such as fruit peels, vegetables, asparagus leaves, wolfberry leaves, and mulberry leaves has a diverse fiber composition and contains antioxidant components such as plant polyphenols. It is known as antioxidant dietary fiber and has better functional characteristics. This type of dietary fiber has a wide range of sources, and reasonable development can greatly increase the added value of agricultural products, which has attracted the attention of many researchers. In the gradually deepening research, it was found that many factors directly affect the structure and components of insoluble dietary fiber during the preparation process, further affecting its physical and chemical functional properties. Especially for raw materials with relatively dense fiber structures, the particle size during the early preparation process is even more crucial. However, the influence of particle size on functional properties is still overlooked in many studies and developments of dietary fiber.

Lotus leaves are the dried leaves of the water lily plant in the family Nymphaeaceae. The Compendium of Materia Medica records that “taking lotus leaves can make people lose weight.” In China, it is often used as a raw material for weight loss, slimming, and lipid-lowering drugs or functional foods. Lotus leaves are rich in polyphenols and dietary fiber, which meet the requirements for natural high-quality dietary fiber sources. At the same time, consumers have a high recognition of lotus leaves. Lotus leaves are a medicinal and edible resource that can be used as auxiliary materials for ordinary foods, with a low development threshold. Lotus leaf dietary fiber has great potential for development as a high fiber food auxiliary material. Most dietary fiber has a rough taste. In order to reduce the adverse effects on the sensory quality of food, dietary fiber is often crushed or even micronized before being added to food. Generally speaking, the smaller the particle size of dietary fiber particles, the higher the sensory evaluation. At the same time, studies have found that particle sizes that are too large or too small are not conducive to the functional properties of insoluble dietary fiber. This article compares and analyzes the structure, functional component content, in vitro adsorption characteristics, and sensory quality of lotus leaf insoluble dietary fiber (LIDF) with four different particle sizes. LIDF is selected as a suitable particle size for high fiber food excipients, providing reference for further research on lotus leaf dietary fiber.

 

 

Lotus leaves are rich in polyphenols and dietary fiber, which meet the natural requirements for high-quality dietary fiber sources and have good potential for development. This experiment compared and analyzed the structure, physicochemical properties, and sensory quality of four different particle sizes of LIDF, and screened the optimal particle size for the development of LIDF as a high fiber food excipient. Lotus leaves were hydrolyzed by amylase, protease, and glucosidase to prepare LIDF. The microstructure showed that pores appeared on the surface of LIDF. As the particle size decreased, the degree of exposure of lotus leaf endoplasmic reticulum reticular fibers increased. Spectral analysis shows that LIDF has a cellulose type I crystal structure, and the decrease in particle size does not cause any changes in the molecular structure of LIDF, which can reduce the crystallinity index of cellulose. As the particle size decreases, the total flavonoid and polyphenol content of LIDF decreases, while the insoluble dietary fiber content increases. The difference in content between the two groups with larger particle sizes (LIDF-A and LIDF-B) and the two groups with smaller particle sizes (LIDF-C and LIDF-D) is more significant. As the particle size decreases, the in vitro adsorption characteristics of LIDF increase and then decrease. LIDF-B and LIDF-C have relatively better in vitro adsorption characteristics, while LIDF particles with larger or smaller particle sizes are not conducive to the in vitro adsorption characteristics of LIDF. The a * value (red), b * value (yellow), and sensory score of LIDF powder increase as the particle size decreases. This experiment combines considerations to evaluate the development potential of LIDF-C (D50 58.35 μ m) as a high fiber functional food excipient, providing a theoretical basis for further research on the functional properties of lotus leaf dietary fiber.