1.1 Equipment

Determination of the relative impact of various significant bioprocess parameters that influence traditional batch propagation of kefir grains and daily kefir grain increase mass using the Taguchi design methodology requires the performance of a series of experiments. In order to ensure the highest quality as well as repeatability of raw experimental data, it is desired to perform those experiments (batch propagations of kefir grains in enriched milk under different bioprocess conditions) in computer controlled state-of-the-art laboratory reactor or fermentor.

Perhaps one of the most user-friendly and at the same time the most efficient high quality aforementioned equipment is heat flow reaction calorimeter RC1 (Mettler Toledo, Greifensee, Switzerland). Basically, the RC1 system is actually both — state-of-the-art computer controlled, electronically safe-guarded bench-scale ‘model’ of a batch/ semi-batch reactor or fermentor from pilot and/or industrial plant (automated lab reactor (ALR)) and at the same time a heat-flow reaction calorimeter. The RC1 system allows real time measurement, monitor and control of all important bioprocess parameters such as rotational frequency of the stirrer, temperature of reaction or fermentation media, reactor jacket temperature, pH value of reaction or fermentation media, mass concentration of dissolved oxygen, amount of added (dosed) material, etc. Primarily, it is designed for determination of the complete mass and heat balance over the course of the entire chemical reaction or physical transformation (e. g. crystallization, dissolution, etc.). In addition, using specific modifications, it can be employed for investigating thermal effects during bioprocess (Marison et al., 1998). This means that by using RC1 system it is possible to gain and/or determine wide range of process thermal data and constants such as specific heat capacity of reaction mixture, heat flow profile of the reaction or physical transformation, reaction enthalpy, maximum heat flow due to reaction or physical transformation, potential adiabatic temperature increase in case of cooling failure, heat accumulation, etc.. All obtained time-depended calorimetric data (heat flow data) can be further used for kinetic studies, etc. The RC1 system enables performance of chemical and also bio(chemical) reactions or physical transformation under different modes such as isothermal conditions, adiabatic conditions, etc. Using RC1 it is possible to perform distillations and reactions (transformations) under reflux with heat balancing. Last but not least, the RC1 system is a recipe driven (managed) which means that all process operations can be programmed or written by recipe beforehand and thus its maximum flexibility is assured. Finally, it is worldwide recognized as an industrial standard to gain safety data for a later scale-up to pilot or production plant.