Activity-loss kinetics of freeze-dried lactic acid starter cultures

Alaeddinoğlu, Gürdal; Güven, Aysel; Özilgen, Mustafa

doi:10.1016/0141-0229(89)90127-0

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…A lowering of the hydrophobicity of membrane phospholipids owing to the introduction of hydrophilic groups and a decrease in ATPase activity might partially explain why upon storage a progressive reduction in the activity of freeze-dried lactic acid bacteria is observed (El-Sadek et aZ., 1975, Alaeddinoglu et al, 1989. According with Malis and Bonventre (1986), oxidation in mitochondria is responsible for an increase in the permeability of the cell membrane to protons.…”

Section: Discussionmentioning

confidence: 99%

“…Microbial cultures can be kept in a "dormant" state, especially if they are kept at low temperatures (Foster, 1962;Clementi and Rossi, 1984). Nevertheless, during storage, bacterial cells are likely to lose their viability and activity (acid production capacity) (Alaeddinoglu et al, 1989). In a previous paper (Castro et aZ., 1993, a change in the lipid profile during storage of Lactobacillus bulgaricus lyophilized in skim milk powder was reported.…”

Section: Introductionmentioning

confidence: 96%

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Changes in the cell membrane of Lactobacillus bulgaricus during storage following freeze-drying

1996

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The mechanism of inactivation of freeze-dried Lactobacillus bu1gaticu.s during storage in maltodextrin under controlled humidity was investigated Evidence is presented supporting the hypothesis that membrane damage occurs during storage. A study on the lipid composition of the cells by gas chromatography showed a decrease in the unsaturated and saturated fatty acid content of the cell. Further evidence indicating membrane damage includes a decrease in membrane bound proton-translocating ATPase activity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Changes in the cell membrane of Lactobacillus bulgaricus during storage following freeze-drying

1996

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“…Calcium may increase the survival rate of microbial cells during freeze drying (King and Su 1993). High concentration of protective agents is not always desirable when a mixture of protection agents is used (Alaeddinoglu et al 1989;Abraham et al 1990). Microencapsulation of probiotic bacteria is another technique that can be used to increase the protection against extreme processing conditions (Sabikhi et al 2008).…”

Section: Introductionmentioning

confidence: 98%

Formulation of Protective Agents for Improvement of Lactobacillus salivarius I 24 Survival Rate Subjected to Freeze Drying for Production of Live Cells in Powderized Form

Ming

Rahim

Wan

et al. 2009

Food Bioprocess Technol

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The effectiveness of formulations using different protective agents to maintain viability of Lactobacillus salivarius I 24 during freeze drying for production of live cell in powdered form was investigated. The influence of prefreezing and cultivation conditions on viability of cells after freeze drying was also studied. Surface methodology was used to determine the most suitable combination of the protective agents. Concentrations of skim milk, sucrose, glycerol, and calcium carbonate were selected as operating variables, and survivals of cultures after freeze drying were used as results. Skim milk and sucrose were better protective agents than glycerol and calcium carbonate when used individually for preserving L. salivarius I 24 during freeze drying. Their protective abilities could be enhanced significantly when using them as a mixture (9.85% w/v skim milk and 10.65% w/v sucrose). Prefreezing of the cells at −80°C for 5 h prior to freeze drying and cultivation with regulated pH and temperature gave the highest cell viability.

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“…Since a small variation of temperature can greatly modify the primary drying time as well as the dried product structure, an accurate determination of the collapse temperature is critical for the process optimization. Although several works have been reported on freeze‐drying of various bacteria (4–8), few data are available on the physical properties of complex biological systems such as freeze‐dried industrial starters (concentrated lactic acid bacteria) used in the manufacturing of fermented milks and cheeses (9). The collapse temperature of these materials has never been explored.…”

Section: Introductionmentioning

confidence: 99%

Collapse Temperature of Freeze-Dried Lactobacillus bulgaricusSuspensions and Protective Media

Fonseca

Passot

Cunin

et al. 2008

Biotechnol Progress

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Optimization of the freeze-drying process needs to characterize the physical state of frozen and dried products. A protocol to measure the collapse temperature of complex biological media such as concentrated lactic acid bacteria using freeze-drying microscopy was first elaborated. Afterward, aqueous solutions of one or several components as well as concentrated lactic acid bacterial suspensions were analyzed in order to study how the structure of these materials is degraded during freeze-drying. A similar behavior toward collapse was observed for all aqueous solutions, which was characterized by two temperatures: the "microcollapse" temperature (T(microc), beginning of a local loss of structure) and the "collapse" temperature (T(c), beginning of an overall loss of structure). For aqueous solutions, these two temperatures were close, differing by less than 3 degrees C. Nevertheless, when lactic acid bacteria were added to aqueous solutions, the collapse temperatures increased. Moreover, the interval between microcollapse and collapse temperatures became larger. Lactic acid bacterial cells gave a kind of "robustness" to the freeze-dried product. Finally, comparing glass transition, measured by differential scanning calorimetry (DSC) and collapse temperature for aqueous solutions with noncrystallizable solutes, showed that these values belonged to the same temperature range (differing by less than 5 degrees C). As suggested in the literature, the glass transition temperature can thus be used as a first approximation of the collapse temperature of these media. However, for lactic acid bacterial suspensions, because the difference between collapse and glass transition temperatures was about 10 degrees C, this approximation was not justified. An elegant physical appearance of the dried cakes and an acceptable acidification activity recovery were obtained, when applying operating conditions during freeze-drying in vials that allowed the product temperature to be maintained during primary drying at a level lower than the collapse temperature of lactic acid bacterial suspensions. Consequently, the collapse temperature T(c) was proposed as the maximal product temperature preserving the structure from macroscopic collapse and an acceptable biological activity of cells.

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Activity-loss kinetics of freeze-dried lactic acid starter cultures

Cited by 11 publications

References 9 publications

Changes in the cell membrane of Lactobacillus bulgaricus during storage following freeze-drying

Changes in the cell membrane of Lactobacillus bulgaricus during storage following freeze-drying

Formulation of Protective Agents for Improvement of Lactobacillus salivarius I 24 Survival Rate Subjected to Freeze Drying for Production of Live Cells in Powderized Form

Collapse Temperature of Freeze-Dried Lactobacillus bulgaricusSuspensions and Protective Media

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