Effect of culture medium and cryoprotectants on the growth and survival of probiotic lactobacilli during freeze drying

To investigate the effects of the medium and cryoprotective agents used on the growth and survival of Lactobacillus plantarum and Lactobacillus rhamnosus GG during freeze drying. A complex medium was developed consisting primarily of glucose, yeast extract and vegetable-derived peptone. Trehalose, sucrose and sorbitol were examined for their ability to protect the cells during freeze drying. Using standardized amount of cells and the optimized freeze drying media, the effect of the growth medium on cell survival during freeze drying was investigated. The results showed that glucose and yeast extract were the most important growth factors, while sucrose offered better protection than trehalose and sorbitol during freeze drying. When the cells were grown under carbon limiting conditions, their survival during freeze drying was significantly decreased. A clear relationship was observed between cell growth and the ability of the cells to survive during the freeze drying process. The survival of probiotic strains during freeze drying was shown to be dependent on the cryoprotectant used and the growth medium.

Effects of drying methods and conditions on antimicrobial activity of edible chitosan films enriched with galangal extract

The aim of this work was to study the effects of drying methods and conditions (i.e., ambient drying, hot air drying at 40 degrees C, vacuum drying and low-pressure superheated steam drying within the temperature range of 70-90 degrees C at an absolute pressure of 10 kPa) as well as the concentration of galangal extract on the antimicrobial activity of edible chitosan films against Staphylococcus aureus. Galangal extract was added to the film forming solution as a natural antimicrobial agent in the concentration range of 0.3-0.9 g/100 g. Fourier transform infrared (FTIR) spectra and swelling of the films were also evaluated to investigate interaction between chitosan and the galangal extract. The antimicrobial activity of the films was evaluated by the disc diffusion and viable cell count method, while the morphology of bacteria treated with the antimicrobial films was observed via transmission electron microscopy (TEM). The antimicrobial activity, swelling and functional group interaction of the antimicrobial films were found to be affected by the drying methods and conditions as well as the concentration of the galangal extract. The electron microscopic observations revealed that cell wall and cell membrane of S. aureus treated by the antimicrobial films were significantly damaged. (C) 2009 Elsevier Ltd. All rights reserved.

Predicting the thermal inactivation of bacteria in a solid matrix: simulation studies on the relative effects of microbial thermal resistance parameters and process conditions

A combined mathematical model for predicting heat penetration and microbial inactivation in a solid body heated by conduction was tested experimentally by inoculating agar cylinders with Salmonella typhimurium or Enterococcus faecium and heating in a water bath. Regions of growth where bacteria had survived after heating were measured by image analysis and compared with model predictions. Visualisation of the regions of growth was improved by incorporating chromogenic metabolic indicators into the agar. Preliminary tests established that the model performed satisfactorily with both test organisms and with cylinders of different diameter. The model was then used in simulation studies in which the parameters D, z, inoculum size, cylinder diameter and heating temperature were systematically varied. These simulations showed that the biological variables D, z and inoculum size had a relatively small effect on the time needed to eliminate bacteria at the cylinder axis in comparison with the physical variables heating temperature and cylinder diameter, which had a much greater relative effect. (c) 2005 Elsevier B.V All rights reserved.

Effects of restricted water availability and increased temperature on the grain filling, drying and quality of winter wheat

Experiments in controlled environments examined the effects of the timing and severity of drought, and increased temperature, on grain development of Hereward winter wheat. Environmental effects on grain specific weight, protein content, Hagberg Falling Number, SDS-sedimentation volume, and sulphur content were also studied. Drought and increased temperature applied before the end of grain filling shortened the grain filling period and reduced grain yield, mean grain weight and specific weight. Grain filling was most severely affected by drought between days 1-14 after anthesis. Protein content was increased by stresses before the end of grain growth, because nitrogen harvest index was less severely affected than was dry matter harvest index. Hagberg Falling Number was increased to the greatest extent by stresses applied 15-28 days after anthesis. Treatment effects on grain sulphur content were similar to those on protein content, such that N:S ratio was not significantly affected by drought nor temperature stresses. The effects of restricted water on grain yield and quality were linearly related to soil moisture between 44 and about 73% field capacity (FC) from days 15-28. Drought stress (but not temperature stress) before the end of grain filling decreased SDS-sedimentation volume relative to drought applied later. (C) 2003 Elsevier Science Ltd. All rights reserved.

Changes in selected biochemical and sensory parameters as affected by the superficial inoculation of Penicillium camemberti on dry fermented sausages

An atoxigenic strain of Penicillium camemberti was superficially inoculated on fermented sausages in an attempt to improve their sensory properties. The growth of this mould on the surface of the sausages resulted in an intense proteolysis and lipolysis, which caused an increase in the concentration of free amino acids, free fatty acids (FFA) and volatile compounds. Many of these were derived from amino acid catabolism and were responsible for the "ripened flavour", i.e. branched aldehydes and the corresponding alcohols, acids and esters. The development of the fungal mycelia on the surface of the sausages also protected lipids from oxidation, resulting in both lower 2-thiobarbituric acid (TBARS) values and lipid oxidation-derived compounds, such as aliphatic aldehydes and alcohols. The sensory analysis of superficially inoculated sausages showed clear improvements in odour and flavour and, as a consequence, in the overall quality of the sausages. Therefore, this strain is proposed as a potential starter culture for dry fermented sausage production. (C) 2002 Elsevier Science B.V All rights reserved.

Robust identification for linear-in-the-parameters models

In this paper new robust nonlinear model construction algorithms for a large class of linear-in-the-parameters models are introduced to enhance model robustness, including three algorithms using combined A- or D-optimality or PRESS statistic (Predicted REsidual Sum of Squares) with regularised orthogonal least squares algorithm respectively. A common characteristic of these algorithms is that the inherent computation efficiency associated with the orthogonalisation scheme in orthogonal least squares or regularised orthogonal least squares has been extended such that the new algorithms are computationally efficient. A numerical example is included to demonstrate effectiveness of the algorithms. Copyright (C) 2003 IFAC.

Estimation of Hidden Markov Models parameters using differential evolution

Hidden Markov Models (HMMs) have been successfully applied to different modelling and classification problems from different areas over the recent years. An important step in using HMMs is the initialisation of the parameters of the model as the subsequent learning of HMM’s parameters will be dependent on these values. This initialisation should take into account the knowledge about the addressed problem and also optimisation techniques to estimate the best initial parameters given a cost function, and consequently, to estimate the best log-likelihood. This paper proposes the initialisation of Hidden Markov Models parameters using the optimisation algorithm Differential Evolution with the aim to obtain the best log-likelihood.

A fast linear-in-the-parameters classifier construction algorithm using orthogonal forward selection to minimize leave-one-out misclassification rate

We propose a simple and computationally efficient construction algorithm for two class linear-in-the-parameters classifiers. In order to optimize model generalization, a forward orthogonal selection (OFS) procedure is used for minimizing the leave-one-out (LOO) misclassification rate directly. An analytic formula and a set of forward recursive updating formula of the LOO misclassification rate are developed and applied in the proposed algorithm. Numerical examples are used to demonstrate that the proposed algorithm is an excellent alternative approach to construct sparse two class classifiers in terms of performance and computational efficiency.

Are differences in life history parameters of the pine beauty moth Panolis flammea modified by host plant quality or gender?

Pine beauty moth (Panolis flammea D&S, Lepidoptera: Noctuidae) were reared individually from egg hatch to pupation on one of three host plants, Pinus sylvestris (native host plant), Pinus contorta (Central Interior seed origin - good quality introduced host) and P. contorta (Alaskan seed origin - poor quality introduced host). After emerging from the pupae the adult moths were confined to a Skeena River seed origin of P. contorta. Female pupal weight and adult life span were significantly higher on P. sylvestris than on the two lodgepole pine seed origins. Development time was, however, not significantly different between treatments, but larval mean relative growth rate was found to be negatively correlated with birth weight and positively correlated with pupal weight. The time to emerge from the pupa was also not significantly different between treatments. However, there were marked differences between the genders. Male moths lost a significantly greater proportion of their weight over the pupal stage but lived significantly longer as adults than the females. Female moths emerged from the pupal stage significantly sooner than male moths. There was no apparent advantage of lai-ge birth size when looked at in terms of subsequent performance. These results are discussed in light of current life history theory.

Oxidatively drying coating composition

coating composition comprising an oxidatively drying coating binder and a chelate comprising at least one group according to the following formula (I): forming a complex with a metal ion, A1 and A2 both being an aromatic residue, R1 and R3 being covalently bonded groups, and R2 being a divalent organic radical, wherein at least one solubilizing group is coivalently bonded to the chelating compound. The solubilizing group is a non-polar group, preferable an aliphatic group having at least four carbon atoms, covalently bonded to A1 and/or A2. The metal ion is a divalent ion of a metal selected from the group of manganese, cobalt, copper, lead, zirconium, iron, lanthanium, cerium, vanadium, and clacium or a trivalent ion of a metal selected from the group of manganese, cobalt, lead, zirconium, iron, lanthanium, cerium, and vanadium, combined with a monovalent counterion.

Single trial BCI operation via Wackermann parameters

Accurate single trial P300 classification lends itself to fast and accurate control of Brain Computer Interfaces (BCIs). Highly accurate classification of single trial P300 ERPs is achieved by characterizing the EEG via corresponding stationary and time-varying Wackermann parameters. Subsets of maximally discriminating parameters are then selected using the Network Clustering feature selection algorithm and classified with Naive-Bayes and Linear Discriminant Analysis classifiers. Hence the method is assessed on two different data-sets from BCI competitions and is shown to produce accuracies of between approximately 70% and 85%. This is promising for the use of Wackermann parameters as features in the classification of single-trial ERP responses.

Using modelling tools to optimise the calculation and subsequent reduction of cable distortion parameters with application to oil well logging systems

This paper discusses how the use of computer-based modelling tools has aided the design of a telemetry unit for use with oil well logging. With the aid of modern computer-based simulation techniques, the new design is capable of operating at data rates of 2.5 times faster than previous designs.

Effects of inulin on lipid parameters in humans

Convincing lipid-lowering effects of the fructooligosaccharide inulin have been demonstrated in animals, yet attempts to reproduce similar effects in humans have generated conflicting results. This may be because of the much lower doses used in humans as a result of the adverse gastrointestinal symptoms exhibited by most subjects consuming daily doses in excess of 30 g. Two studies that fed either oligofructose (20 g/d) or inulin (14 g/d) observed no effect on fasting total, LDL or HDL cholesterol, or serum triglycerides. Two other studies that fed inulin either in a breakfast cereal (9 g/d) or as a powdered addition to beverages and meals (10 g/d) reported similar reductions in fasting triglycerides (227 and 219%, respectively). In one of these studies, total and LDL cholesterol concentrations were also modestly reduced (5 and 7%, respectively). Because animal studies have identified inhibition of hepatic fatty acid synthesis as the major site of action for the triglyceride-lowering effects of inulin, and because this pathway is relatively inactive in humans unless a high carbohydrate diet is fed, future attempts to demonstrate lipid-lowering effects of inulin should consider the nature of the background diet as a determinant of response.