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Biological Fate of Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
S. Parthasarathi, C. Anandharamakrishnan
The intestinal compartment is divided into three parts: duodenum, a short section receiving digestive secretions from the pancreas and liver, and two longer ones, the jejunum and ileum. The small intestinal segment is responsible for the breakdown of macromolecules and absorption of water and nutrients. In the duodenum, acidic chyme is neutralized by sodium bicarbonate (NaHCO3) and the secretion of pancreatic enzymes (containing proteases, amylases, and lipases) and other digestive enzymes helps in the breakdown of food constituents. Bile secretio n (produced by the liver) plays a crucial role in lipid digestion by emulsifying dietary fats into small droplets promoting pancreatic lipase activity. The segmentation and peristalsis activities of the intestinal segment allow chyme to mix and propel the digesta through the small intestine. Water and nutrients are absorbed by villus enterocytes via different mechanisms: simple diffusion, facilitated diffusion, or active transport (Guerra et al., 2012).
Properties of Starch and Modified Starches
Published in Jean-Luc Wertz, Bénédicte Goffin, Starch in the Bioeconomy, 2020
Jean-Luc Wertz, Bénédicte Goffin
The digestion of polysaccharides such as starch includes four steps22: In the mouth: Digestion begins in the mouth. The salivary glands in the mouth secrete saliva, which helps moisten the food. The food is then chewed while the salivary glands also release α-amylase, which begins the process of breaking down the polysaccharides.In the stomach: After the carbohydrate food is chewed into smaller pieces and mixed with salivary amylase and other salivary juices, it is swallowed and passed through the esophagus. The mixture enters then the stomach. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme. There is no further digestion in the stomach, as the latter produces acid, which destroys bacteria in the food and stops the action of the salivary amylase.In the pancreas and small intestine: After being in the stomach, the chyme enters the beginning portion of the small intestine, called the duodenum. In response to chyme being in the duodenum, the pancreas releases the enzyme pancreatic amylase, which breaks the polysaccharide down into a disaccharide. The small intestine then produces enzymes called lactase, sucrase, and maltase, which break down the disaccharides into monosaccharides. The monosaccharides are then absorbed in the small intestine.In the large intestine (colon): Carbohydrates that are not digested and absorbed by the small intestine reach the colon where they are partly broken down by intestinal bacteria.
Simulation based investigation of 2D soft-elastic reactors for better mixing performance
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Changyong Li, Stefan Gasow, Yan Jin, Jie Xiao, Xiao Dong Chen
Biology is a rich source of innovative ideas that can be the inspiration to find successful alternatives for solving specific and challenging problems in the chemical industry (Chen, 2016; Coppens, 2012). Chemical engineering equipment and processes, designed and built by imitating biological systems (including physical, chemical and mechanical structures), can lead to superb performance (Chen, 2016). The digestive systems of people and animals can be thought of as a series of miniature chemical reactors in which various unit operations occur (Chen & Yoo, 2006). The muscle tissues of the digestive organs exhibit peristaltic movements (a series of wavelike muscle contractions), and there is no mixing device (e.g. static mixer or impeller) in the lumen to promote the mixing. From an engineering viewpoint, the digestive tract is composed of multiple soft chemical reactors (Chen, 2016). These chemical reactors are special since none of them has a conventional agitation devices inside. They can be classified as soft-elastic reactors, whose walls are not rigid and the mixing is initiated by wall movements (Liu, Xiao, et al., 2018). The digestive tract can effectively enhance the mixing, crushing and transport of chyme, which mainly attributes to the physiological structure and wall motion of the digestive system (Liu, Xiao, et al., 2018; Liu, Zou, et al., 2018). In recent years, biological reactors in the digestive tract have gained more and more attention (Ji et al., 2021; Li, Yu, et al., 2020; Li, Zhu, et al., 2020; Wu & Chen, 2020). Chen et al. carried out food digestion studies using ‘near real’ in vitro digestive systems. Those systems take into account the physical movements, digestion environment and realistic morphology of digestive organs. For example, the human stomach system was used to investigate the effects of gastric morphology (including the complex geometrical shape and internal wrinkles) on emptying behaviors (Chen et al., 2016). The soft tubular model reactor was used to mimic the small intestine, based on which Deng et al. (2016) concluded that the movement of the reactor wall can accelerate starch hydrolysis. The rat stomach model, fabricated with the aid of 3D-printing technology, was used to explore the effects of the injection pattern of the gastric juice and the contraction frequency on the digestibility of casein powder suspensions (Zhang et al., 2018). Extended from those efforts, a prototype soft-elastic reactor (SER) was constructed to offer one potential alternative to traditional mixing equipment with rigid walls and agitators (Liu, Xiao, et al., 2018; Liu, Zou, et al., 2018). It is a standard cylindrical-shaped container made from silicone, in which the mixing is induced by the wall deformation triggered by the periodic protrusion of a beater from one side of the vessel (Chen & Liu, 2015). It was found that the SER could effectively mix highly viscous fluids (Liu, Xiao, et al., 2018).