The viability of complex coacervates encapsulated probiotics during simulated sequential gastrointestinal digestion as affected by wall materials and drying methods

Authors: QI, XIAOXI - North Dakota State University; LAN, YANG - North Dakota State University; Ohm, Jae-Bom; CHEN, BINGCAN - North Dakota State University; RAO, JIAJIA - North Dakota State University

Submitted to: Food & Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2021
Publication Date: 6/29/2021
Citation: Qi, X., Lan, Y., Ohm, J., Chen, B., Rao, J. 2021. The viability of complex coacervates encapsulated probiotics during simulated sequential gastrointestinal digestion as affected by wall materials and drying methods. Food & Function. 12:8907-8919. https://doi.org/10.1039/D1FO01533H.
DOI: https://doi.org/10.1039/D1FO01533H

Interpretive Summary: Probiotics are living microorganisms that can provide numerous health benefits. Probiotics are effective when they survive passage through the digestive tract in humans. However, the majority of probiotics die in the digestive tract. The viability of probiotics can be increased by encapsulation. Few reports have been published on the use of plant proteins in probiotic encapsulation. Pea protein isolates are plant-based proteins while sodium caseinate is a protein found in animals. They are potentially useful in probiotic encapsulation. This research aimed to evaluate the protective effect of pea protein isolate and sodium caseinate on probiotics. A protein process procedure was established to improve encapsulation of probiotics in a preliminary experiment. The result indicated that pea protein isolates performed better than sodium caseinate in protection of probiotics when used as an encapsulation material. The information attained from this research will be a valuable reference in the development of plant-based materials that are useful in encapsulation of probiotics.

Technical Abstract: The objective of this study was to investigate the impact of protein type (sodium caseinate and pea protein isolate), protein to sugar beet pectin mixing ratio (5:1 and 2:1) on complex coacervation formation, as well as the finishing technology (freeze-drying and spray-drying) for improving the viability of encapsulated Lactobacillus rhamnosus GG (LGG) in the complex coacervates during simulated sequential gastrointestinal (GI) digestion. The physicochemical properties of LGG encapsulated microcapsules in liquid and powder form were evaluated. The state diagram and '-potential results indicated the pH 3.0 was the optimum coacervates formation pH in the current systems. Confocal laser scanning microscopy (CLSM), viscoelastic analysis, and Fourier transform infrared spectroscopy (FTIR) confirmed that the gel-like network structure of complex coacervates were successfully formed between protein and SBP at pH 3.0 through electrostatic interaction. In terms of physiochemical properties and viability of LGG encapsulated in the microcapsules powder, drying method played a crucial role on particle size, microstructure and death rate of encapsulated LGG during simulated sequential GI digestion compared to protein type and biopolymer mixing ratio. For example, the microstructure of spray-dried microcapsules exhibited smaller spherical particles with some cavities, whereas the larger particle size of freeze-dried samples showed porous sponge network structure with larger particle sizes. As a result, spray-dried LGG microcapsules generally had a lower death rate during simulated sequential gastrointestinal digestion compared to the freeze-dried counterpart. Among all samples, spray-dried PPI'SBP microcapsules demonstrated superior performance against cell loss and maintained more than 7.5 Log CFU/g viable cells after digestion.