The study, published in Innovative Food Science & Emerging Technologies, noted that the design of biopolymer-based micro-particles to encapsulate, protect and release specific bioactive nutrients that are believed to benefit human health is gaining widespread interest.
Led by J. Burgain from the Université de Lorraine, France, the researchers also noted that the use of dairy ingredients to protect certain nutraceuticals has become commonplace, however their use for the protection of probiotic strains remains less explored.
The team therefore explored the possibility of encapsulation of Lactobacillus rhamnosus GG in a combination of micro-particles made up of milk proteins in differing combinations of casein, native whey and/or denatured whey proteins. These were then subjected to a model of digestion to assess survival.
"Although the initial particles were similar, their disintegration in simulated gastric media was totally different and characterized by two stages. An initial decrease in particle size more or less quick depending on the protein composition was followed by a stable phase characterized by the particle size and shape retention," explained Burgain and his colleagues.
While they noted that a 'significant' amount of intact particles were still noticeable at the end of a gastric simulation for each formulation - the formulation containing a mix of casein and denatured whey presented the best bacterial survival (99%) and encapsulation rate (97%) when compared to those containing either only casein or casein and native whey or casein in mixture with native and denatured whey proteins.
Applications and further work
"The industrial aims are to optimise and control the processes to suit the needs of industrial criterions: encapsulation rate, gastric resistance, intestinal release, storage in the final food," explained the research team - who added that the next step of their work is to use the micro-particles identified in the current study for the protection of other sensitive bioactives against adverse environmental conditions encountered in the stomach.
"Studies are under progress for polyphenolic compounds and other probiotic bacteria," they said.
In addition to their findings on the micro-particles themselves, the research team noted that for the first time, original equipment was used to follow in situ the micro-particle size and shape evolution during digestion in the stomach.
"This equipment could be used in the future to improve the target delivery of bioactives by a simple, direct and easy method," they stated.
Volume 19, Pages 233–242, doi: 10.1016/j.ifset.2013.04.012
‘Encapsulation of Lactobacillus rhamnosus GG in microparticles: Influence of casein to whey protein ratio on bacterial survival during digestion’
Authors: J. Burgain, C. Gaiani, C. Cailliez-Grimal, et al