A fiber-optic refractive index sensor detects the isoelectric point of gelatin

Abstract

In the present study, a set-up and a rapid method were developed to determine the isoelectric point (pI) of gelatin based on the combination of an automatic adding solution technique and fiber-optic refractive index sensing. The refractive index of the gelatin aqueous solution was measured as a function of pH and time using a fiber-optic sensor and pH meter. This is a typical acid-base titration process. The peak pH values of the refractive index-pH curve indicate the pI of the gelatins. With the aid of virtual instrument technology, the data acquisition, process and display were automatic, having the advantages of quick and labor saving. Furthermore, this improved analysis efficiency and reduced manual disturbance, which was typically an approximately 15 min period. The pI of these two kinds of gelatin, sample 1 and 2 were determined through this method and the pI s were consistent with the values obtained using a rotary viscometer. The test results revealed that this method is rapid, sensitive, accurate, and labor and reagent saving, and has the potential for the rapid determination of the pI of amino acids and proteins.

GRAPHICAL ABSTRACT

Keywords:

• gelaitn
• isoelectric point
• fiber-optic
• refractive index
• virtual instrument
• LabVIEW

PUBLIC INTEREST STATEMENT

Gelatin is a kind of low calorie health food with high nutritional value, which can be used to make confectionery additives, frozen food additives and so on. In addition, gelatin is widely used in medicine and chemical industry. Isoelectric point (pI) is one of the most important physical and chemical properties of gelatin, which will affect its application to a great extent. Therefore, the accurate determination of the pI of gelatin is of great academic significance as well as potential application price in some aspects. The research aim is to develop a new, rapid, simple and accurate technology to determine the pI of gelatin. The method is easy to operate. The results show that the method is reliable.

Acknowledgements

The authors gratefully acknowledge the financial support for this work from the Science and Technology Program of Guangzhou, China (201607010096)

Competing interests

The authors declare no competing interests.

Cover image

Source: Hui Su, Xu Guang Huang. Fresnel-reflection-based fiber sensor for on-line measurement of solute concentration in solutions. Sensors and Acutators B, 126 (2007) 579-582.

Correction

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the Science and Technology Program of Guangzhou [201607010096];

Notes on contributors

Chun Hua Tan

Chun Hua Tan, the corresponding author, is working as Associate Professor in South China Normal University, Guangzhou, China. He has received the Master of Science (Analytical Chemistry) degrees from China University of Geosciences of Wuhan, China, in June, 2000, and received the Doctor of Science (Optics) degrees from South China Normal University of Guangzhou, China, in June, 2005. His research interests are aimed at analytical chemistry and optical fiber sensing. The main research focus of his research group is to develop simple fiber-optic sensing technology for the determination of chemical parameters and to develop new fluorescent materials and studying their applications.