Speaker Normalization and Model Selection of Combined Neural Networks

This paper introduces bootstrap error estimation for automatic tuning of parameters in combined networks, applied as front-end preprocessors for a speech recognition system based on hidden Markov models. The method is evaluated on a large-vocabulary (10 000 words) continuous speech recognition task. Bootstrap estimates of minimum mean squared error allow selection of speaker normalization models improving recognition performance. The procedure allows a flexible strategy for dealing with inter-speaker variability without requiring an additional validation set. Recognition results are compared for linear, generalized radial basis functions and multi-layer perceptron network architectures.     

VISCOELASTIC PROPERTIES OF WHEY PROTEIN CONCENTRATE GELS WITH HONEY AND WHEAT FLOUR AT DIFFERENT pH

Viscoelasticity of heat-induced gels from whey protein concentrate, with different contents of honey and wheat flour, and prepared at pH 3.75, 4.2 and 7.0, was studied by using dynamic rheological assays. The elastic modulus of gels prepared at neutral pH was higher than the corresponding to acidic gels, probably due to the fact that sulphydryl-disulfide interchange reactions are favored at neutral pH. Honey decreased the elastic modulus and increased the viscous modulus and the complex viscosity in all conditions assayed. Wheat flour increased the elastic modulus, and all samples exhibited a gel-type behavior except at high honey content.

PRACTICAL APPLICATIONS

Honey and wheat flour modifies the properties of whey protein concentrate gels. Both components have opposite effects: honey increases the viscous-like behavior and wheat flour the solid-like behavior of gels in all conditions assayed. The different characteristics of gels prepared at different pHs and with different amounts of honey and wheat flour could be used in different formulated foods, as desserts.     

Fatigue damage analysis based on energy parameters in reinforced polyamide

This article proposes an analysis method for the identification of the damage caused in a reinforced polyamide fatigue process through the evolution of the generated energy per cycle. Monotonous fatigue tests have been carried out at different stress levels using Polyamide 6 reinforced with short fibre glass tensile specimens. The loss of mechanical properties is measured using a damage parameter, defined as the variation in energy per cycle with respect to the initial conditions. Three clearly differentiated zones can be distinguished in the evolution of damage as a function of the energy per cycle. The first zone is one of deaccelerated rapid growth; in the second, the damage grows linearly, so that the damage growth speed can be determined as a function of the potential of variation of the stress applied; and finally, the third is a zone of accelerated growth of the damage until fracture.     

SEROLOGIC IDENTIFICATION OF SPECIES OF ORIGIN OF SAUSAGE MEATS

SUMMARY: A partially purified immunoglobulin G (lgG) solution prepared from the serum of species to be tested was heated to the specifications for sausages. The resulting supernatant fluid was decanted and the precipitate washed with saline and used to immunize rabbits. The supernatant fluid was used to sensitize tanned sheep red blood cells. The immune serum was rendered monospecific by absorptions with heterologous, heated lgG precipitates. A sample of monospecific immune serum was absorbed with a washed homogenate of sausage. Aliquots of the monospecific immune serum, both untreated and sausage absorbed, were tested with cells sensitized with the homologous heated lgG supematant fluid. A significant reduction of titer by sausage absorption indicated that the sausages contained the meat homologous to the immune serum.     

Characterisation of three temperate phages released from the same Lactobacillus paracasei commercial strain

Lysogeny entails more economical and technological risks in probiotic Lactobacillus casei/paracasei bacteria than in other lactic acid bacteria, due to economic value. Lysogeny is widely spread among L. casei/paracasei strains. Siphophages C_L1 and C_L2, isolated from noninfected lysed‐cultures of commercial L. paracasei A, are thermoresistant, have identical host spectrum, latent and burst times, whereas burst sizes are 148 and 85, respectively. Mitomycin C induction of L. paracasei A yielded prophage iA2, whose presence was confirmed on the strain genome and whose restriction patterns differed from phages C_L1 and C_L2. The latter shared several restriction fragments, probably indicating a common origin.     

MODELING THE INACTIVATION KINETICS OF ESCHERICHIA COLI O157:H7 DURING THE STORAGE UNDER REFRIGERATION OF APPLE JUICE TREATED BY PULSED ELECTRIC FIELDS

The aim was to describe the inactivation kinetics of Escherichia coli O157:H7 suspended in apple juice after pulsed electric fields (PEF) and a subsequent storage under refrigeration. Escherichia coli O157:H7 showed a great PEF resistance in apple juice, when survivors were evaluated immediately after PEF. However, PEF-treated cells exhibited a great sensitivity to a subsequent holding in apple juice for 3 days. For instance, although a PEF treatment of 80 pulses at 35.0 kV/cm inactivated less than 0.5 log₁₀ cell cycles, the maintenance of the samples up to 3 days at 4C caused an inactivation of 5.0 log₁₀ cycles. An equation based on the Weibullian-like distribution accurately described the kinetics of cell inactivation.

PRACTICAL APPLICATIONS

The storage time influences the pulsed electric fields (PEF) inactivation of Escherichia coli O157:H7 cells suspended in apple juice. The potential of Weibullian-like distributions to describe survival curves with deviations in their linearity has allowed us to obtain an equation that accurately describes the complete PEF survival profile of E. coli in apple juice, when survivors were evaluated immediately after PEF and also after a subsequent storage under refrigeration. These results underline the possibility of applying PEF to pasteurize acidic foods by taking into account the postprocessing effect of the acidity of the product.     

INACTIVATION OF ESCHERICHIA COLI O157:H7 DURING THE STORAGE UNDER REFRIGERATION OF APPLE JUICE TREATED BY PULSED ELECTRIC FIELDS

The sensitivity of pulsed electric fields (PEF)‐treated E. coli O157:H7 cells to subsequent holding in apple juice has been evaluated. Escherichia coli O157:H7 cells in apple juice were resistant to PEF. A PEF treatment of 400 µs at any electrical field strength was not sufficient to inactivate one log₁₀cycle of cells. However, PEF injured a large proportion of E. coli O157:H7 cells that became sensitive to a subsequent storage under refrigeration in apple juice. The total lethal effect of the combined process depended on the electrical field strength and storage time. The combination of a PEF treatment at 25 kV/cm for 400 µs and a subsequent storage of the apple juice under refrigeration for 48 h allowed five log₁₀cycles of inactivation to be achieved. The combination of PEF and maintenance under refrigeration has been demonstrated to be an effective pasteurization method, by sufficiently reducing the presence of E. coli O157:H7 in apple juice in order to meet U.S. FDA recommendations.