Microencapsulation of Lacticaseibacillus rhamnosus GG ATCC 53103 by freeze-drying: evaluation of storage stability and survival in simulated infant gastrointestinal digestion

It is important for the probiotic to maintain its viability during food processing, gastrointestinal conditions, and storage. This study was aimed to apply the freeze-drying process to microencapsulate probiotic Lacticaseibacillus rhamnosus GG ATCC 53103. Wall materials consisted of whey protein isolate (WPI), WPI + fructooligosaccharides (WPI + FOS), WPI + galactooligosaccharides (WPI + GOS), and WPI + FOS + GOS. The results showed optimal levels of moisture content (3.85–4.1%) and water activity (0.087–0.115) in the freeze-dried powder (FDP) that contributed to the survival of L. rhamnosus during storage. The morphology of un-encapsulated FDP indicated cell deformation and pile up whereas, for encapsulated samples, they were well entrapped and randomly distributed. Freeze-dried free cells were larger than encapsulated cells, irrespective of the wall material type. The survival rate results were over 96% after freeze-drying, depending on the type of wall materials. However, in the simulated infant gastrointestinal digestion, WPI + FOS + GOS-encapsulated cells showed a minimum decline in cellular survival. The survival of encapsulated probiotics was about 11.2 and 10.22 log cfu/g before storage and at 24 weeks of storage, respectively. This decline in survivability is within an acceptable range since the encapsulated L. rhamnosus GG 53103 are for incorporation into an infant formula powder. Overall, the data demonstrated that using combination of wall materials shows a better protective effect when encapsulated L. rhamnosus GG 53,103 is freeze dried and can be used in infant formula and baby food industries.