Alternative Drying Processes for the Industrial Preservation of Lactic Acid Starter Cultures

Abstract

The preservation of lactic acid starter cultures by alternative drying processes has attracted increasing attention due to the high costs and energy consumption of freezing and freeze drying. This review thus aims to provide a survey regarding the state of knowledge of starter culture production at high levels of viability. The results from numerous studies on various drying processes and lactic acid bacteria are summarized. The alternative drying processes considered, such as spray drying, fluidized bed drying, and vacuum drying, are mainly of industrial interest. The features, advantages, and disadvantages of these drying processes are described. In conclusion, the important factors that need to be considered, standardized, or optimized to achieve high levels of viability include intrinsic tolerance of cultures, growth media and conditions, stress induction, cell harvesting conditions, protective agents, rehydration conditions, enumeration of cells, and storage conditions.

Influence of Temperature and Drying Time on Extraction Yield of Phenolic Compounds from Grape Pomace Variety “Portogizac”

“…Furthermore, fluid-bed drying generates lower costs than freeze-drying 38 . This method is suitable for drying grains and other particulate materials.…”

“…This method is suitable for drying grains and other particulate materials. Application of fluid-bed drying for drying seeds 39 , lactic acid starter culture 38 , olive pomace 40 has been investigated previously. However, reports on fluid-bed drying of grape pomace in the literature are scarce concerning its effects on the phenolic content and antioxidant activity of extracts.…”

Influence of lyophilization, fluidized bed drying, addition of protectants, and storage on the viability of lactic acid bacteria

“…Furthermore the findings underline the need of strain selection with regard to the performance during fermentation and downstream processing. In addition the fact that fluidized bed drying produces less than a fifth of the fixed and manufacturing costs estimated for freeze drying (Santivarangkna et al 2007) needs to be considered when choosing a drying method on a large scale.…”

“…For many years lactic acid bacteria have been mainly preserved by freeze drying, which is a gentle, but timeconsuming and expensive drying method (Ratti 2001;Morgan et al 2006;Santivarangkna et al 2007). Spray drying would allow inexpensive production of large amounts, as the costs of spray drying can be six times lower per kilogram water removed than the cost of freeze drying (Knorr 1998).…”

“…Furthermore this study comprises a direct comparison of the drying methods lyophilization and fluidized bed drying in terms of survival of lactic acid bacteria, which is often impossible due to distinct experimental setups and strains applied. In general, literature on fluidized bed drying of lactic acid bacteria -especially on pilot scale as done in this studyis limited (Santivarangkna et al 2007). The effect taken by protective carbohydrate compounds on bacterial cells was investigated because the preconditioning of bacterial cells prior to the drying process appears to be of particular importance.…”