Atmospheric Freeze-Impingement Drying of an Autochthonous Microencapsulated Probiotic Strain

Abstract

The purpose of this study was to evaluate the viability of an autochthonous lactic acid bacteria with probiotic activity (Lactobacillus acidophilus) encapsulated in alginate beads and dehydrated using atmospheric freeze-impingement drying. Different materials were used to protect the strain (lactic solids, monosodium glutamate, and sorbitol). It was demonstrated that microencapsulated strains can be dried successfully. After 3 h of drying the worst result was 87% of survival without protection, and the best result was 100% of survival using a mixture of whey protein, sucrose, monosodium glutamate, sorbitol, and magnesium stearate as a protective agent. The moisture of dehydrated product containing a microencapsulated Lactobacillus acidophilus strain was in the range of 6 to 10%, ensuring its shelf life. The drying kinetics showed the typical exponential decay associated with control of the process by diffusion and were successfully modeled by semi-empirical equations derived from Fick's law.

Products obtained using this kind of stabilization operation are a good alternative to reducing the consumption of antibiotics, avoiding that viability and desired properties depend on incorrect preservation methods, reducing their access to other high demanding markets. In addition, the potential to dehydrate microencapsulated biomaterials in a lab-scale prototype of an impingement jet system adapted as an atmospheric freeze dryer is shown.

Keywords:

• Atmospheric freeze drying
• Encapsulation
• Impingement
• Probiotics

ACKNOWLEDGMENT

This study received financial support from FONDECYT Grant 1110097.

Notes

^a Maltodextrin.

^b Reconstituted skim milk.

^c Data not available.

^d Soy protein isolate.

^e Whey protein isolate.