Hydration kinetics of direct expanded tef flour breakfast cereals in water and milk
Hydration kinetics of tef flour breakfast cereals extruded at barrel temperatures of 110, 130, and 150°C was investigated by hydrating them in water and whole milk at 25°C (±1°C). The normalized Weibull model described the rehydration characteristics of the extrudates in water and milk adequately (R2 = 0.98–0.99). Water absorption rate was significantly (P < 0.05) influenced by barrel temperature where extrudates processed at 150°C barrel temperature exhibited high water absorption rate followed by those extruded at 130 and 100°C, respectively. Hydration rate and equilibrium moisture content were higher for samples hydrated in water than those in milk. In view of the values of the shape parameter β, the hydration process is predominantly controlled by diffusion (β = 0.40–0.51) for samples extruded at 110°C whereas external resistance to mass transfer dominated (β = 0.60–0.73) those extruded using 150 and 130°C. Extrudates processed at 130 and 150°C exhibited better hydration characteristics. Thus, these temperature ranges could be used to produce extruded products from tef.
Kinetics of moisture uptake and soluble‐solids loss by puffed breakfast cereals immersed in water
Breakfast cereals readily take up moisture when immersed in a liquid medium, leading to undesirable changes in texture. The mechanism of moisture uptake is related to both the water movement within the cereal and the ability of the cereal to hydrate. In this work, the kinetics of moisture uptake and soluble-solids loss by puffed corn and peanut butter breakfast cereals immersed in water were experimentally measured under isothermal conditions covering a wide range of temperatures (5-55 °C). Different mathematical models, often reported in the literature to describe soaking processes, were applied to the experimental data. Peleg, first-order, diffusion and Weibull models were used. The fit provided by the first two models was clearly biased, and the best results were obtained with the Weibull model. The equilibrium conditions were found to be independent of temperature. whereas the rate constants showed an Arrhenius-type dependency. The relaxation phenomena, which are related to the hydration of the cereal matrix, are probably the main controlling step of the process. Furthermore, fat content appears to play a major role in the ability of the cereal to hydrate, with fat hindering the process.
First Insights into the Draft Genome Sequence of the Endophyte Paenibacillus amylolyticus Strain GM1FR, Isolated from Festuca rubra L.
ABSTRACT Paenibacillus amylolyticus strain GM1FR is an endophyte isolated from aerial plant tissues of Festuca rubra L. Here, we report the draft genome sequence (7.3 Mb) of GM1FR containing 6,241 protein-coding genes, some of which are potentially involved in plant growth promotion and biocontrol.