Microarray gene expression classification with few genes: Criteria to combine attribute selection and classification methods

Microarray data classification is a task involving high dimensionality and small samples sizes. A common criterion to decide on the number of selected genes is maximizing the accuracy, which risks overfitting and usually selects more genes than actually needed. We propose, relaxing the maximum accuracy criterion, to select the combination of attribute selection and classification algorithm that using less attributes has an accuracy not statistically significantly worst that the best. Also we give some advice to choose a suitable combination of attribute selection and classifying algorithms for a good accuracy when using a low number of gene expressions. We used some well known attribute selection methods (FCBF, ReliefF and SVM-RFE, plus a Random selection, used as a base line technique) and classifying techniques (Naive Bayes, 3 Nearest Neighbor and SVM with linear kernel) applied to 30 data sets involving different cancer types.     

Effect of dietary fibre on dough rheology and bread quality

Dietary fibre is a common and important ingredient of a new generation of healthy food products demanded more each day by customers. Dietary fibre increases the nutritional value of bread but usually at the same time alters rheological properties of dough and, finally, the quality and sensorial properties of bread. The present work investigates the effect of some purified dietary fibres from different origins (orange, pea, cocoa, coffee, wheat and microcrystalline cellulose) on the rheological properties of wheat flour dough and the final quality of breads. The study of the rheological behaviour of the dough was performed by means of a consistograph and an alveograph. Bread quality was determined by means of texture, colour and specific volume measurements after baking under controlled conditions. The influence of fibre on bread sensory evaluation was established. Dietary fibre additions, in general, had pronounced effects on dough properties yielding higher water absorption, mixing tolerance and tenacity, and smaller extensibility in comparison with those obtained without fibre addition (in the control bread). Regarding the effect on bread properties, the fibre always enhanced the shelf life, as textural studies revealed. Sensory evaluations revealed that dietary fibres, with the exception of those from coffee and cocoa, can be added to flour at the level of 2% without deterioration of the bread palatability in comparison with white flour bread. Additions of 5% could imply the use of some additives to correct the rheological properties of dough.     

Quantitative analysis of flavour volatiles detects differences among closely related traditional cultivars of tomato

Volatile compounds with a major contribution to aroma have been quantitatively determined in four traditional tomato cultivars and one commercial F1 hybrid. One of the traditional cultivars was the most appreciated for flavour and overall acceptability in tests performed using a panel of 30 untrained tasters. The same cultivar showed significantly higher contents of hexanal and cis‐3‐hexenal volatile compounds, which have been previously reported to be two of the most important contributors to tomato flavour. On the basis of a small number of fruits per cultivar, significant differences among very closely related tomato cultivars can be detected for volatile aromas, thus allowing the use of the determination of volatiles as a possible tool in tomato breeding programs, making even the selection of single plants possible. Copyright © 2004 Society of Chemical Industry     

Effect of final products on the kinetics of 1-phenylethanol oxidation with air

Oxidation of 1-phenylethanol with air at atmospheric pressure in the liquid-phase has been studied establishing the influence of the main reaction products: hydrogen peroxide and acetophenone. Kinetic equations describing the system evolution have been obtained.At low initial concentrations (about 0.1 M) hydrogen peroxide acts like an initiator of radical chains promoting the oxidation rate of 1-phenylethanol. At higher concentrations, the radicals recombine producing water and thereby, reducing peroxide production.The presence of acetophenone in reaction medium has not an important effect on the rate of 1-phenylethanol oxidation but participates in several secondary reactions when reacting with hydrogen peroxide.