Differential effects of polymers PVP90 and Ficoll400 on storage stability and viability ofLactobacillus coryniformisSi3 freeze‐dried in sucrose

Abstract

Aims: To investigate the effect of freeze‐dried Lactobacillus coryniformis Si3 on storage stability by adding polymers to sucrose‐based formulations and to examine the relationship between amorphous matrix stability and cell viability. Methods and Results: The resistance to moisture‐induced sucrose crystallization and effects on the glass transition temperature (Tg) by the addition of polymers to the formulation were determined by different calorimetric techniques. Both polymers increased the amorphous matrix stability compared to the control, and poly(vinyl)pyrrolidone K90 was more effective in increasing amorphous stability than Ficoll 400. The viability of Lact. coryniformis Si3 after storage was investigated by plate counts following exposure to different moisture levels and temperatures for up to 3 months. The polymers enhanced the cellular viability to different degrees, dependent upon polymer and storage condition. Conclusions: Polymers can be used to enhance the stability of freeze‐dried Lact. coryniformis Si3 products, but cell viability and matrix stability do not always correlate. The general rule of thumb to keep a highly amorphous product 50° below its Tg for overall stability seemed to apply for this type of bacterial products. We showed that by combining thermal analysis with plate counts, it was possible to determine storage conditions where cell viability and matrix stability were kept high. Significance and Impact of the Study: The results will aid in the rational formulation design and proper determination of storage conditions for freeze‐dried and highly amorphous lactic acid bacteria formulations. We propose a hypothesis of reason for different stabilizing effects on the cells by the different polymers based on our findings and previous findings.

Next Generation Drying Technologies for Pharmaceutical Applications

“…Vacuum dried L. paracasei was reported to be highly stable during storage at 4°C, and no significant inactivation was reported following 3 months of storage. This result is in accordance with studies on storage of freeze‐dried lactic acid bacteria . Comparatively, the inactivation rate constants of cells dried by vacuum drying were lower than those of the same strain dried by freeze‐drying.…”

“…This result is in accordance with studies on storage of freeze-dried lactic acid bacteria. 217,218 Comparatively, the inactivation rate constants of cells dried by vacuum drying were lower than those of the same strain dried by freeze-drying. Conrad et al 219 examined the effect of vacuum drying on the stability of Lactobacillus acidophilus (L. acidophilus).…”

Role of Glassy State on Stabilities of Freeze‐Dried Probiotics

“…It was suggested that in order to achieve nearly complete reduction of molecular movements, amorphous pharmaceutical solids should be stored 50 °C below T g (Hancock and others 1995). Similar findings were reported also in a study with L. coryniformis by Schoug and others (2010) and with L. rhamnosus by Miao and others (2008) where viability of cells clearly decreased at T – T g higher than –50 °C and ca. –30 °C, respectively.…”

Impact of matrix properties on the survival of freeze‐dried bacteria

“…The formulated cell suspensions were freeze dried in a pilot plant freeze dryer (Lyostar II; FTS Kinetics, Stone Ridge, NY, USA) using a previously developed method optimised for freeze drying of sucrose 35. Briefly, 10 ‐mL glass vials were filled with 1–2 mL of the formulated cell suspensions, cooled on the shelf in the freeze dryer at 5 °C min −1 until a temperature of − 50 °C was reached and held isothermally at that temperature for 50 min.…”