Crispy banana obtained by the combination of a high temperature and short time drying stage and a drying process

The effect of the high temperature and short time (HTST) drying stage was combined with an air drying process to produce crispness in bananas. The fruit was dehydrated in an air drier for five minutes at 70 degrees C and then immediately set at a HTST stage (130, 140, 150 degrees C and 9, 12, 15 minutes) and then at 70 degrees C until water activity (a(w)) was around 0.300. Crispness was evaluated as a function of water activity, using sensory and texture analyses. Drying kinetics was evaluated using the empirical Lewis model. Crispy banana was obtained at 140 degrees C-12min and 150 degrees C-15min in the HTST stage, with a(w) = 0.345 and a(w) = 0.363, respectively. Analysis of the k parameter (Lewis model) suggests that the initial moisture content of the samples effects this parameter, overcoming the HTST effect. Results showed a relationship between sensory crispness, instrumental texture and the HTST stage.22228529

Changes in the physical properties of bananas on applying HTST pulse during air-drying

The effect of high temperature (HTST) pulse on the air-drying of banana slices was studied and compared with the conventional air-drying process. The Exponential and Page models fitted the experimental data of the dehydration kinetics for both processes well. The different drying treatments led to distinctive structural changes in the samples, affecting the shrinkage and porosity. The combined HTST/air-drying process simultaneously puffed and dried the banana slices, resulting in reduced shrinkage compared with the conventional air-dried samples. For conventionally air-dried samples, the increase in porosity reached a value of 32% at the end of the process. During the HTST/air-drying process, the porosity increment reached values of from 45% to 53% at the end of drying, resulting in the formation of a highly porous structure, which occurred together with an expansion in volume. Structural observations of the banana samples during the processes studied were able to explain the volume and porosity changes. (c) 2007 Elsevier Ltd. All rights reserved.83453154

A salvage pathway maintains highly functional respiratory complex I

Regulation of the turnover of complex I (CI), the largest mitochondrial respiratory chain complex, remains enigmatic despite huge advancement in understanding its structure and the assembly. Here, we report that the NADH-oxidizing N-module of CI is turned over at a higher rate and largely independently of the rest of the complex by mitochondrial matrix protease ClpXP, which selectively removes and degrades damaged subunits. The observed mechanism seems to be a safeguard against the accumulation of dysfunctional CI arising from the inactivation of the N-module subunits due to attrition caused by its constant activity under physiological conditions. This CI salvage pathway maintains highly functional CI through a favorable mechanism that demands much lower energetic cost than de novo synthesis and reassembly of the entire CI. Our results also identify ClpXP activity as an unforeseen target for therapeutic interventions in the large group of mitochondrial diseases characterized by the CI instability. Maintenance and quality control of the mitochondrial respiratory chain complexes responsible for bulk energy production are unclear. Here, the authors show that the mitochondrial protease ClpXP is required for the rapid turnover of the core N-module of respiratory complex I, which happens independently of other modules in the complex