Table 1.

Summary of two‐layer microparticles for probiotic delivery

Fabrication technique	Core component/s	Shell component/s	Probiotic strain	Results	Ref.
Extrusion + Dip coating	Ca cross‐linked alginate	Chitosan	Saccharomyces boulardii	Enhanced storage viability (120 days at 30 °C), and gastrointestinal resistance compared to single alginate particles.	[ 85 ]
Emulsion + Dip coating	Ca cross‐linked alginate oligosaccharide	Chitosan oligosaccharide	Bifidobacterium longum	20% reduction in cell viability after in vitro gastrointestinal testing, compared to 40% for alginate containing particles. Improved growth and increased amount of probiotics in the intestine (mice), leading to reduced pathogenic bacteria.	[ 86 ]
Emulsion + Dip coating	Ca cross‐linked alginate	Chitosan	Bifidobacterium longum	50% improvement in viability loss after 180 days at 25 °C, compared to free cells. Only 30% reduction in viability after gastrointestinal testing, compared to 100% reduction for single alginate particles.	[ 70 ]
Electrospray + Dip coating	Ca cross‐linked alginate	Chitosan	Lactobacillus plantarum	Excellent gastric‐mucoadhesion after 120 min of washing with simulated gastric fluid (Ex vivo‐porcine gastric mucosa).	[ 88 ]
Emulsion + Dip coating	Ca cross‐linked alginate	Chitosan	Enterococcus sp. (Fluorescent labeled)	6 Logs higher cell concentration in the gastrointestinal tract (In vivo‐ Black‐footed abalone), compared to conventionally fed animals.	[ 68 ]
Extrusion + Dip coating	Ca cross‐linked polyacrylate‐grafted alginate	Chitosan	Lactobacillus plantarum (Fluorescent labeled)	Cell viability increased by ninefold after incubation in simulated intestinal and colon fluids. 5 Logs and 2 Logs higher cell viability in ileum and colon (In vivo Wistar rats), respectively (compared with alginate particles).	[ 71 ]
Extrusion + Dip coating	Ca cross‐linked alginate	Chitosan cross‐linked with Na‐tripolyphosphate	Lactobacillus plantarum	Lowest reduction in cell viability after simulated gastrointestinal conditions, compared to single alginate and chitosan‐coated alginate.	[ 90 ]
Emulsion + Dip coating	Ca cross‐linked alginate	PVP‐co‐DMAEMA	Lactobacillus plantarum	Significantly higher cell viability after 24 h in osmotic stress, compared to not coated particles	[ 92 ]
Extrusion + Dip coating	Ca cross‐linked alginate	Zein	Bifidobacterium bifidum	Maximum viable cell count with minimum log reduction after exposure to SGJ and SIF. Highest cell viability after 32 days storage at 4 °C.	[ 63 ]
Extrusion + Dip coating	Ca cross‐linked alginate + various grades of inulin	Chitosan	Lacticaseibacillus casei	Microparticles containing long‐chain inulin had the lowest reduction in viability upon gastrointestinal and bile salts testing, when compared to pristine alginate–chitosan formulations.	[ 72 ]
Electrospray + Dip coating	Ca cross‐linked alginate + long‐chain inulin or resistant starch	Chitosan	Lactobacillus plantarum or Bifidobacterium lactis	Microcapsules containing resistant starch had a better cell viability under gastrointestinal conditions. On the other hand, inulin‐containing microcapsules improved the survival of cells during 90 days of storage (at 25, 4, or −18 °C).	[ 100 ]
Extrusion + Dip coating	Ca cross‐linked alginate + xanthan gum	Chitosan	Lactobacillus plantarum	Higher cell viability after exposure to simulated gastric fluid when compared to chitosan‐coated alginate particles.	[ 102 ]
Extrusion + Dip coating	Ca cross‐linked alginate + pea protein	Chitosan	Lacticaseibacillus rhamnosus and Lactobacillus helveticus	No loss in viable cell counts observed after treatment with simulated gastrointestinal conditions in samples stored under different temperatures (4 or 22 °C).	[ 103 ]
Emulsion + Dip coating	Ca cross‐linked pectin + green tea extract	Whey protein isolate	Lactobacillus helveticus	After exposure to simulated gastric juice, the mean survival rate of cells in core–shell microparticles containing 1000 µg mL−1 GTE was significantly higher (100%) than the one of cells in core–shell formulations without GTE (69%).	[ 67 ]
Electrospray + Dip coating	Ca cross‐linked alginate	Egg albumen + stearic acid	Lactobacillus acidophilus	Increase in relative proportion of stearic acid led to enhanced encapsulation efficiency, and significant improvement in viability of encapsulated cells exposed to the moist‐heat treatment	[ 65 ]
Co‐extrusion	Sunflower oil	Ca cross‐linked alginate + Shellac	Lactobacillus acidophilus	Higher cell viability after both storage and exposure to gastrointestinal conditions when compared to particles without shellac.	[ 108 ]
Co‐extrusion	Sunflower oil or Coconut fat	Ca cross‐linked alginate + Shellac	Lactobacillus paracasei	Core–shell particles containing alginate–shellac blend in the shell and coconut fat in the effectively protected the encapsulated probiotic under simulated gastrointestinal conditions, as compared to particles with sunflower oil.	[ 35 ]