There has been huge industrial interest in improving the stability of beneficial bacterial strains through the use of microencapsulation techniques - leading to a boom in research in the area in research in recent years.
Writing in LWT - Food Science and Technology, a team of Chinese researchers now believe that an encapsulation material made from alginate and an arabinoxylan (AX) prebiotic could improve survival rates by around 50%.
Using a simulated gastrointestinal model, microspheres prepared by co-gelation of sodium alginate (SA) and arabinoxylan (AX) significantly increased gastric stability, encapsulation efficiency and bile salt resistance.
“Compared to microspheres formed by alginate alone, the AX composite microspheres significantly improved the encapsulation efficiency (2.5 folds), gastric stability (survival rate from 51.1% to 74.0%) and the bile salt resistance (survival rate from 70.6% to 81.6%),” wrote Professor Genyi Zhang, leader of the study team from the School of Food Science and Technology, Jiangnan University, Wuxi, China.
Arabinoxylan is a dietary fibre found in the cell walls of cereal grains, which has previously been shown to produce health-giving metabolites and has been identified as a prebiotic.
The researchers subsequently incorporated the oligosaccharide form of arabinoxylan (AXOS) into the AX-SA microspheres. This further increased the encapsulation efficiency from 67% to 85%, as well as inducing further improvements in probiotic survival rate, bile salt resistance and storage stability.
Fermentation with AXOS of the probiotic strain (Lactobacillus plantarum) used in the study showed a decrease in pH of the culture medium and molecular weights of AX and AXOS and an increase in the number of live L. plantarum. This finding confirmed the prebiotic capability of AX and AXOS.
Possible mechanism
The researchers found evidence that the SA and AX molecules became physically entangled in the composite microspheres. This effect, together with co-gelation of the two materials, may combine to entrap the bacteria in the SA-AX network, the scientists suggested.
The promising findings using simulated gastrointestinal conditions justify further research in humans, the scientists advocated.
“Positive results of high encapsulation efficiency and high resistance to gastrointestinal conditions make the synbiotic encapsulation an efficient approach to deliver probiotics, which also warrants further in vivo study to explore the colonization of probiotics and resulted health benefits,” commented Zhang.
If in vivo trials also prove successful, the technique could be an effective means of delivering both probiotics and prebiotics together, the researchers concluded.
Source: LWT - Food Science and Technology
Volume 93 (2018), pages 135-141, doi: 10.1111/jam.12762
“Synbiotic encapsulation of probiotic Lactobacillus plantarum by alginate-arabinoxylan composite microspheres”
Authors: Yue Wu, Genyi Zhang