Thermal Characteristics of Lactobacillus Plantarum on Various Types of Carrier for Starter Powder Preparation

Abstract

Mocaf  fermentation  usually carried out by depping raw cassava in water and added by lactic acid starter.  Powder starter for mocaf fermentation prepared by Solid State Fermentation (SSF) has not been provided.  Actually this method able for  energy saving use for drying the fermented product. in so far there is now starter powder for mocaf  fermentation is still no data. Whereas this proses design for starter production is very important for support this kind for fermentation. In relation of starter powder production the higher viability and stability the strain should be found in starter. Thermal characteristics of Lactobacillus plantarum on various carrier and its thermal conductivity is required to design the process starter production with high viability. The aim of the study was to determine the heat resistance of  L. plantarum cells on several carriers so determine the best carrier and thermal conductivity of the carrier needed for designing a good starter production. Heat resistance cells were measured by determining the value of D and Z of the cell on different carrier. Three kinds of carrier are tapioca starch, rice flour and grated cassava. Heat resistance measurements using Yamazaki et al. (1997) method. Thermal conductivity of the carrier using  Heat Conduction Apparatus Radial Conduction (HCARC). The results show that thermal conductivity of carrier was 0.460, 0.455, and 0.453 W/m⁰C, for rice-flour, grated cassava and tapioca-flour respectively. Based on the heat resistance test, the highest D value (9.17 h) was obtained when rice flour was heating at 35â°C and its Z value was 20â°C, so the rice flour is the best for carrier among others carriers.    Based on these data the process for starter powder production could be designed using L. plantarum with rice flour carrier at 55â°C for 55 minutes to get the cells concentration 10⁹ cel/g, if desired only 1 log cycle reduction in cells content. Prolonged heating to 2.75 h would reduce 3 log cycles of cells amount to get the starter powder with cel viability 10⁶ cel/g.