토토 사이트 순위 systems refer to the state in which insoluble liquids are stably dispersed in other liquids and can be found in many products, such as foods, cosmetics, and household goods. The main 토토 사이트 순위 system is liquid phase. However, currently, consumers are negatively concerned about the use of chemical surfactants in liquid 토토 사이트 순위 system and many researchers try to replace them;; Professor Young Jin Choi's research team of College of Agriculture and Life Sciences of Seoul National University focused on Pickering 토토 사이트 순위s involving the use of solids as emulsifying agents.
Pickering 토토 사이트 순위, proposed by Pickering in 1904, refers to a stabilized 토토 사이트 순위 involving the use of solid particles, unlike traditional 토토 사이트 순위s that stabilize with surfactants. Only solid particles that are amphiphilic to water and oil can stabilize 토토 사이트 순위s. Professor Choi (Corresponding Author) and Myeongsu Jo(First Author) have established a research plan to overcome the above problems. They used starch as an emulsifying agent in Pickering 토토 사이트 순위. Among organic solid particles, starches are easy to control the properties such as size and amphiphilicity.
Solid particles used in Pickering 토토 사이트 순위 should be amphiphilic. Because natural starch has a higher affinity to water than oil, it is necessary to combine octenyl succinic acid (OSA) with starch to increase affinity to oil. In addition, because natural starch is too large (typically up to tens of mm), Pickering 토토 사이트 순위 stabilized with it results in large fat globules dispersed in water, which breaks the stability leading to separate the water and oil layers in the end. To overcome this, it is necessary to reduce its size less than tens of nm by hydrolysis of starch. Then, Pickering 토토 사이트 순위 systems with those starch nanocrystals (SNC) have a fat globule size from tens of nm to hundreds of nm . Therefore, this research team combined the process of starch hydrolysis with that of attaching octenyl succinic anhydride to starch to manufacture modified starch (OSA-SNC) for use in Pickering 토토 사이트 순위.
The size and shape of modified starch were observed using transmission electron microscopes (scale bar is 300 nm) in Fig. 1. The average size is approximately 42 nm.
Fig. 2. Atomic force microscopy and the height profile of OSA-SNC embedded at the oil/water interface (left) and the schematic representation and the calculated angle of OSA-SNCs embedded at the interface (right).
Modified starch produced by Professor Choi has a size of approximately 40 nm and has almost the same level of hydrophilicity and lipophilicity unlike hydrophilic natural starch. The Pickering 토토 사이트 순위 system, stabilized using this modified starch, had fat globules with a size of approximately 500 nm, and its stability lasted for 2 months in a neutral and alkaline environments.
[Pickering 토토 사이트 순위 Stabilized with Chitosan in Acidic Environment]
However, Pickering 토토 사이트 순위 stabilized with modified starch was found to be that it only lasts for approximately 10 days in an environment with a pH of <4.5. Taking advantage of the fact that this problem is owing to the loss of surface charge in acidic environments of the stabilized Pickering 토토 사이트 순위 with modified starch, Professor Choi’s research team conducted a study to coat the surface of Pickering 토토 사이트 순위 having a negative charge with chitosan that has a strong positive charge in acids.
Fig. 3.In vitrochanges in digestive process of Pickering 토토 사이트 순위 stabilized with modified starch and chitosan.
Fig. 3 is an illustration of the observed shape of Pickering 토토 사이트 순위 stabilized with modified starch and chitosan in the digestive tract environment via confocal laser scanning microscopy (scale bar size 10 μm). Pickering 토토 사이트 순위 stabilized with modified starch and the same added with chitosan coating are well dispersed and stable without being aggregated in the pre-ingestion or oral phase before exposure to the digestive tract environment. In the case of Pickering 토토 사이트 순위 stabilized only with modified starch when exposed to the gastric phase, 토토 사이트 순위 particles are formed into large lumps; however, in the case of Pickering 토토 사이트 순위 in which chitosan coating is added, it does not cohere and remains stable in a well-dispersed form. When exposed to the small intestinal phase for 2 hours, Pickering 토토 사이트 순위 stabilized only with modified starch formed mixed micelles after full lipolysis. On the other hand, in case of Pickering 토토 사이트 순위 stabilized with modified starch and chitosan, some droplets formed mixed micelles but some were undigested showing their original shapes. And the higher amount of chitosan coated, the lower the digestion occurred.The 토토 사이트 순위 stabilized with modified starch and chitosan showed excellent stability under acidic conditions.
Therefore, the digestion rate of Pickering 토토 사이트 순위s can be controlled by controlling the amount of chitosan coating.Fig. 4 shows the degree to which 토토 사이트 순위 is digested over time in the small intestine by adding 0.0%, 0.1%, and 0.4% chitosan coating to Pickering 토토 사이트 순위 stabilized with modified starch. It showed that the higher the amount of chitosan coating added, the lower the initial digestion rate and the total digestion amount for 2 hours.
In the case of an 토토 사이트 순위 system used primarily to transport health functional substances, if stability is not maintained within the digestive tract or if it is digested extremely fast, there is a risk that the concentration of health-functioning substances in a particular location will rise sharply and cause side effects. Therefore, this study is significant because the results have indicated that it is possible to control the digestion rate of Pickering 토토 사이트 순위 through chitosan coating.
Professor Choi’s research team effectively stabilized the 토토 사이트 순위 system, which is widely used in food, medicine, and cosmetics, with the use of modified starch instead of surfactants that are avoided by consumers. The 토토 사이트 순위 stabilized with modified starch and chitosan have important advantages such as maintaining stability for 2 months in the pH range of 1–11; this 토토 사이트 순위 can be widely used as a carrier of health functional substances and material aspects that do not involve the use of surfactants as well as for protecting health functional substances in the mouth and stomach and controlling the digestive speed in the small intestine.
Jo, Myeongsu, a Ph.D. candidate in the Department of Agricultural and Biotechnology, analyzed all the properties of the Pickering 토토 사이트 순위 system using modified starch and confirmed its stability; the researcher explained the further plan to confirm whether it is actually absorbed well in the intestines by putting health functional substances inside. Professor Choi, Young Jin stated that they are conducting research to modify the surface of the 토토 사이트 순위 system for enhancing its lasting effects while it is in the intestine so that it can control the digestion speed.
Members of Professor Choi’s laboratory are trying to incorporate nanotechnology into food studies. Professor Choi stated that “There are three major areas of research in our laboratory. We are performing related studies as those on nanomaterials as well as those utilizing nanotechnology related to 토토 사이트 순위 systems, those on developing nanobiosensors that can quickly detect harmful factors in foods, and those on processes for optimizing food processing steps, which are the areas of traditional food engineering.”
The findings of Professor Choi’s team on Pickering 토토 사이트 순위 were published in the Food Hydrocolloids, the most influential international journal in the food sector (Food Hydrocolloids (2018) 84, 343-352, Food Hydrocolloids (2019) 94, 603-612), in recognition of its originality and importance.
《Professor Young Jin Choi》
Written byJeongyeon Kim, Shi-Eun Yoo
Student Press of College of Agriculture and Life Sciences
