Foam‐Mat Freeze‐Drying of Bifidobacterium longum RO175: Viability and Refrigerated Storage Stability

Abstract

Foaming as a pretreatment was used prior to freeze-drying of Bifidobacterium longum RO175 to investigate the potential acceleration of the drying rate and increase in microorganism viability after the process. A study on storage of foamed and nonfoamed freeze-dried products at 4 °C completed this study. B. longum RO175 in foamed medium could be freeze-dried in 1/7 to 1/4 of the time required for nonfoamed suspensions. In addition, foamed suspensions presented higher viability immediately after freeze-drying (13.6% compared to 12.81 % or 11.46%, depending on the cryoprotective media). Refrigerated storage led to a reduction in B. longum RO175 viability for all tested protective agents (foamed and nonfoamed). No correlation between glass transition temperature and stability of probiotic powders was observed during storage. In addition, lower viability after 56 d of storage was observed for foamed materials, probably due to foam porous structure and higher hygroscopicity, and oxygen presence and moisture pickup during storage.

Dual Porosity Protein-based Scaffolds with Enhanced Cell Infiltration and Proliferation

“…The suggested method, in turn, allows facilitated diffusion of water molecules and sublimation of ice crystals without damaging the structural integrity of the scaffold. Indeed, the trapped bubbles not only reduce the diffusion resistance compared to condensed phase, but also provide a high surface area for mass transfer, ultimately improving the drying rate and quality 35 . Using this strategy, the deformation could be avoided and the shrinkage reduced to less than 5%, as pointed out in the “Results” section.…”

Effect of foaming agents on process conditions, characteristics, and stability of foam‐mat freeze‐dried pandan (Pandanus amaryllifolius) powder

“…Physicochemical properties of the control and the foam-mat freeze-dried pandan powder during storage time at 4 and 37ºC. F-EW = foam-mat with egg white protein, F-NaCn = foam-mat with sodium caseinate, and F-Mix = foam-mat with the mixture of egg white protein, sodium caseinate, and METHOCEL Izquierdo-Lopez et al (2016) reported the disadvantages of F-FD, mainly due to the porous foam structure and high hygroscopicity of F-FD samples which allow oxygen and moisture to become attached to samples during storage in a refrigerator. The porous structure of FDPP or F-FDPPs allows moisture and oxygen to react more easily with the samples, whereas foaming agents (EW, NaCn, and their mixture with METHOCEL) might provide a film barrier surrounding the particles of pandan powder, which could retard moisture adsorption and oxygen exposure.…”

“…The porosity of freeze-dried products allows water to adsorb rapidly, thus enhancing high solubility as well as maintaining the original color pigment and fragrant compound. However, the porosity and hygroscopicity of the end product may lead to an increase in oxidation reactions during utilization and storage and destabilize the powder ingredients (Izquierdo-Lopez, Goulet, & Ratti, 2016).…”

“…In their experiment, the FD rate of foamed apple juice was faster than that of nonfoamed apple juice for equal sample thicknesses. A smaller EW bubble size provides a larger surface to volume ratio for heat and mass transfer during drying and can shorten the FD time when compared to methylcellulose foams Izquierdo-Lopez et al (2016). reported the potential of F-FD to accelerate the drying rate.…”

Impact of hydrocolloid and foaming agent on the physicochemical, microstructural and bioactive characteristics of foam‐mat freeze‐dried tapai (fermented black glutinous rice) powder

“…However, the primary disadvantage of this procedure is the duration of time required for drying. To shorten the freeze‐drying time, foaming is used prior to the dying process (Izquierdo‐López et al, 2017 ).…”