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Fermentation efficiency of thermally dried kefir
Harris Papapostolou1, Loulouda A Bosnea, Athanasios A Koutinas
1Food Biotechnology Group, Section of Analytical Environmental and Applied Chemistry, Department of Chemistry, University of Patras, GR-26500 Patras, Greece.
Bioresource Technology
|February 23, 2008
Summary
Convective drying of kefir biomass enhances ethanol production from whey fermentation. Conventional drying is better for lactic acid production, but both methods show reduced fermentability after storage.
Area of Science:
- Biotechnology
- Food Science
- Microbiology
Background:
- Kefir biomass is a rich source of microorganisms with potential applications in fermentation.
- Thermal drying is a common method for preserving microbial biomass, but its effect on fermentative activity needs investigation.
- Optimizing drying methods is crucial for maintaining the viability and functionality of kefir biomass for industrial applications.
Purpose of the Study:
- To evaluate the impact of three thermal drying methods (conventional, vacuum, convective) on kefir biomass.
- To assess the effect of dried kefir biomass on cell viability and fermentation kinetics of lactose and whey.
- To determine the optimal drying method for maximizing ethanol and lactic acid production.
Main Methods:
- Kefir biomass was dried using conventional, vacuum, and convective methods at temperatures of 28, 33, and 38°C.
- Drying rates were compared across the different methods and temperatures.
- Fermentations using the dried kefir biomass were conducted to measure ethanol and lactic acid production, as well as productivity and yield.
Main Results:
- Convective drying exhibited higher drying rates than conventional and vacuum methods across all tested temperatures.
- Whey fermentations with convectively dried kefir biomass yielded higher ethanol concentrations, productivity, and yield.
- Conventional drying resulted in higher lactic acid concentrations compared to vacuum and convective methods.
- Storage of convectively dried kefir biomass at 33°C for 4 months reduced fermentability, decreasing ethanol and lactic acid productivity by 31% and 20%, respectively.
Conclusions:
- Convective drying is superior for enhancing ethanol production in whey fermentation using kefir biomass.
- Conventional drying is more effective for lactic acid production.
- While storage impacts fermentability, dried kefir biomass retains significant fermentative activity, indicating its potential as a preserved microbial agent.
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