Development and Fundamental Characteristics of a Human Gastric Digestion Simulator for Analysis of Food Disintegration

Gastric digestion is the major digestion process in humans and is strongly affected by both physical and chemical digestion. In vitro approaches using different gastric digestion models have received a great deal of attention in several scientific and industrial fields, including food science and technology, due to experiments being conducted under various conditions and with better reproducibility of the experiment data. The development of simple in vitro gastric digestion devices that enable quantitative consideration of the influence of gastric peristalsis has been necessary for simulating and analyzing the disintegration of solid foods in the stomach. The authors and co-workers recently developed a human gastric digestion simulator (GDS) that simplifies the antrum geometry, is capable of simulated gastric peristalsis, and which enables direct observation of the disintegration of food particles in the gastric contents. This article provides a brief overview of our findings regarding the GDS. First, the concept and development of the GDS is introduced. The disintegration characteristics of representative (model) foods using the GDS are described next, providing insights into the digestion processes influenced by gastric peristalsis. After further improvement, the GDS is expected to offer potential as a tool for designing novel nutraceutical and functional foods for which digestibility is well controlled. Discipline: Food Additional key words: Antrum, direct observation, human stomach, in vitro device, peristalsis *Corresponding author: e-mail isaok@affrc.go. jp Received 28 December 2015; accepted 26 May 2016. Introduction The stomach is a major digestive organ in the human body and plays important roles in disintegrating ingested foods into smaller sizes, and making the nutrients and functional components embedded in them accessible to digestion and adsorption. The human digestion process can be divided into physical, chemical, and biological processes. The oral digestion process that includes mastication and swallowing is greatly influenced by the physical digestion process. The small-intestinal digestion process depends on the chemical digestion process as well as the physical digestion process. The biological digestion process entailing a sort of microbial fermentation occurs in the large intestine. Unlike the processes described above, the gastric digestion process is strongly affected by both the physical and chemical digestion processes. The stomach has functions such as for storing a bolus (a masticated mixture of food particles and saliva) in its upper part (body), mixing, breaking down, and grinding of the gastric contents, induced by peristalsis that is generated on the gastric wall, chemical and enzymatic reactions of the gastric contents with gastric fluid secreted from the gastric wall, and the emptying of gastric digesta (chyme) from the gastric outlet (pylorus) (Kong et al. 2008). Food particles in the bolus usually undergo dramatic changes as a result of the physical and chemical digestion processes. It is therefore important to simulate and analyze the gastric digestion process for a better understanding of key gastric digestion phenomena and the design of novel foods with adequately controlled digestibility. Gastric digestion studies of foods have been conducted