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

Alaeddinoğlu, G.
Güven, Abamuesluem
Özilgen, Mustafa
Lactic acid starter cultures were freeze-dried in whey and nonfat skim milk (NFSM) suspending media with varying amounts of glycerol, adonitol, and sucrose as the additives. Generally additives had different cryoprotective effects in NFSM and whey media. There was also an optimum cryoprotective additive concentration where viability and activity were protected best. The best results were obtained with freeze-dried L. bulgaricus with 0.29 m sucrose, 0.75 m adonitol, or 0.75 m glycerol in whey medium. Similarly, the best protection was obtained with S. thermophilus with 1 m, 0.5 m, and 0.75 m adonitol in NFSM medium and 1 m adonitol in whey medium. Viability loss during freeze-dried storage was modeled with a first-order kinetic expression in viable cell concentration. Activity loss was modeled with a first-order kinetic expression in activity. The major cause of activity loss was death of the microorganisms. Activity loss and viability loss were parallell during storage; an occasional deviation from such a parallel trend occurred due to the presence of injured microorganisms that did not produce lactic acid.
Enzyme and Microbial Technology


OZADALI, F; OZILGEN, M (Springer Science and Business Media LLC, 1988-09-01)
Fed-batch fermenters are generally operated with the addition of small doses of nutrients, therefore the volume of the fermentation broth increases with time. Batch fermenters generally contain and almost constant volume of broth and a logistic equation has been commonly employed to simulate microbial growth in them. Mass balances were determined with fed-batch fermentation to obtain expressions which account for the effect of volume increase and the subsequent dilution of the biomass. A growth rate express...
Kinetics of riboflavin production by Brewers' yeasts
Tamer, I.M.; Özilgen , Mustafa; Ungan, Suat (Elsevier BV, 1988-12)
The kinetics of riboflavin production by Saccharomyces cerevisiae and Saccharomyces carlsbergensis in synthetic media and wort were studied. The results indicated that riboflavin was produced by growing cells only. Riboflavin production rate was proportional to growth rate of the yeasts in the exponential phase. Riboflavin was depleted in the stationary phase. The depletion rate was expressed with a first-order kinetic expression in yeast concentration. The kinetics of substrate utilization and ethanol prod...
BOZOGLU, F; OZILGEN, M; BAKIR, U (Elsevier BV, 1987-09-01)
Survival kinetics of lactic acid starter cultures were modeled considering the microorganism and external medium interfacial area as the critical factors determining the resistance of the microorganisms to freeze-drying. Surviving fraction of the microorganisms increased with the increasing biomass concentration during freeze-drying, and this is attributed to the mutual shielding effect of the microorganisms against the severe conditions of the external medium. Survival of the microorganisms over the storag...
AKDOGAN, H; OZILGEN, M (Elsevier BV, 1992-02-01)
Microbial growth, gas production, and volume increase were studied experimentally at 10-degrees-C, 15-degrees-C, 20-degrees-C, 25-degrees-C, and 30-degrees-C in a sourdough production process. Microbial growth was simulated with the logistic equation. Gas production and dough volume increase rates were simulated with the Luede-king-Piret and saturation equations, respectively. In a leavening process, carbon dioxide is produced by the Bakers' yeast and entrapped into the gas cells formed by the gluten fil...
Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus
Sevinç, Pelin; Gündüz, Ufuk; Department of Biotechnology (2010)
Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth...
Citation Formats
G. Alaeddinoğlu, A. Güven, and M. Özilgen, “Activity-loss kinetics of freeze-dried lactic acid starter cultures,” Enzyme and Microbial Technology, pp. 765–769, 1989, Accessed: 00, 2020. [Online]. Available: