Article

Development and Evaluation of Probiotic Delivery Systems using the Rennet-induced Gelation of Milk Proteins

Ho-Kyung Ha1,2, Ji-Young Hong3, Istifiani Lola Ayu4, Mee-Ryung Lee4,*, Won-Jae Lee3,**
Author Information & Copyright
1Department of Animal Science and Technology, Sunchon National University, Sunchon 57922, Korea.
2Interdisciplinary Program in IT-Bio Convergence System, Sunchon National University, Sunchon 57922, Korea.
3Department of Animal Bioscience (Institute of Agriculture and Life Science), Jinju 52828, Korea.
4Department of Food and Nutrition, Daegu University, Gyeongsan 38453, Korea.
*Corresponding Author: Mee-Ryung Lee, Department of Food and Nutrition, Daegu University, Gyeongsan 38453, Korea, Republic of. Phone: +82-53-850-6837. E-mail: mrlee@daegu.ac.kr.
**Corresponding Author: Won-Jae Lee, Department of Animal Bioscience (Institute of Agriculture and Life Science), Jinju 52828, Korea, Republic of. Phone: +82-55-772-1884. E-mail: wjleewisc@gnu.ac.kr.

© Copyright 2021 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: May 27, 2021; Revised: Jul 09, 2021; Accepted: Jul 21, 2021

Published Online: Jul 26, 2021

Abstract

The aims of this study were to develop a milk protein-based probiotic delivery system using a modified rennet-induced gelation method and to determine how the milk protein concentration level and pH, which can affect the rennet-induced intra- and inter-molecular association of milk proteins, affect the physicochemical properties of the probiotic delivery systems, such as the particle size, size distribution, encapsulation efficiency, and viability of probiotics in simulated gastrointestinal tract. To prepare a milk protein-based delivery system, skim milk powder was used as a source of milk proteins with various concentration levels from 3% to 10% (w/w) and rennet was added to skim milk solutions followed by adjustment of pH from 5.4 or 6.2. <italic>L</italic>.<italic> rhamnosus</italic> GG was used as a probiotic culture. In confocal laser scanning microscopic images, globular particles with a size ranging from 10 μm to 20 μm were observed, indicating that milk protein-based probiotic delivery systems were successfully created. When the milk protein concentration was increased from 3% to 10% (w/w), the size of the delivery system was significantly (p <italic>&lt; </italic>0.05) increased from 27.5 μm to 44.4 μm, while a significant (<italic>p </italic>&lt; 0.05) increase in size from 26.3 μm to 34.5 μm was observed as the pH was increased from 5.4 to 6.4. An increase in the milk protein concentration level and a decrease in pH led to a significant (<italic>p</italic> &lt; 0.05) increase in the encapsulation efficiency of probiotics. The viability of probiotics in a simulated stomach condition was increased when probiotics were encapsulated in milk protein-based delivery systems. An increase in the milk protein concentration and a decrease in pH resulted in an increase in the viability of probiotics in simulated stomach conditions. It was concluded that the milk protein concentration level and pH were the key manufacturing variables affecting the physicochemical properties of milk protein-based probiotic delivery systems.

Keywords: milk protein; probiotics; delivery system; rennet