Methodological developments in bread staling assessment: application to enzyme-supplemented brown pan bread

In this study, texture profile analysis (TPA) at 40 and 80% compression and a newly proposed penetration test were used to evaluate the effects of amylolytic and non-amylolytic enzymes on the textural properties of fresh and stored brown pan breads. The correlations between instrumental parameters and sensory attribute results obtained by a trained panel of assessors were also investigated. Comparison of the results obtained through TPA at the two compression rates was very useful, as the 40% compression TPA hardly reflected the changes that took place in the enzyme-supplemented bread samples over a storage time of 20 days. The penetration curve profiles provided very valuable information, which complemented the TPA for the purposes of assessing bread ageing and the effect of adding enzymes.     

Influence of a pore-forming agent on swelling,network parameters,and permeability of poly(ethylene glycol)-crosslinked poly(methyl vinyl ether-co-maleic acid) hydrogels: Application in transdermal delivery systems

We characterized hydrogels, prepared from aqueous blends of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG 10,000 Daltons) containing a pore-forming agent (sodium bicarbonate, NaHCO₃). Increase in NaHCO₃ content increased the equilibrium water content (EWC) and average molecular weight between crosslinks (M_c) of hydrogels. For example, the %EWC was 731, 860, 1109, and 7536% and the M_c was 8.26, 31.64, 30.04, and 3010.00 × 10⁵ g/mol for hydrogels prepared from aqueous blends containing 0, 1, 2, and 5% w/w of NaHCO₃, respectively. Increase in NaHCO₃ content also resulted in increased permeation of insulin. After 24 h, percentage permeation was 0.94, 3.68, and 25.71% across hydrogel membranes prepared from aqueous blends containing 0, 2, and 5% w/w of NaHCO₃, respectively. Hydrogels containing the pore-forming agent were fabricated into microneedles (MNs) for transdermal drug delivery applications by integrating the MNs with insulin-loaded patches. It was observed that the mean amount of insulin permeating across neonatal porcine skin in vitro was 20.62% and 52.48% from hydrogel MNs prepared from aqueous blends containing 0 and 5% w/w of NaHCO₃. We believe that these pore-forming hydrogels are likely to prove extremely useful for applications in transdermal drug delivery of biomolecules. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Physico–chemical,morphological, and pasting properties of Pine nut (Araucaria angustifolia) starch oxidized with different levels of sodium hypochlorite

The objective of this work was to study the effect of process temperature and active chlorine concentration on the main properties of Pine nut starch (PN). Samples of PN were oxidized with sodium hypochlorite at concentrations varying from 0.5 to 4.0 g active chlorine/100 g starch, at temperatures varying from 20 to 45°C according to a central composite rotational design, analyzing the results using response surface methodology. The concentration of active chlorine had an effect on the WSI, the quantity of carboxyl and carbonyl groups, the AM content and the percentage of light transmittance (650 nm) of the PN. The effect of temperature was observed on the water solubility index, the quantity of carbonyl groups and the percentage of light transmittance (650 nm) of the PN. Oxidation was more intense in the starch treated with 3.5% active chlorine.     

Assessing the performance of methods to detect and quantify African dust in airborne particulates

African dust (AD) contributions to particulate matter (PM) levels may be reported by Member States to the European Commission during justification of exceedances of the daily limit value (DLV). However, the detection and subsequent quantification of the AD contribution to PM levels is complex, and only two measurement-based methods are available in the literature: the Spanish-Portuguese reference method (SPR), and the Tel Aviv University method (TAU). In the present study, both methods were assessed. The SPR method was more conservative in the detection of episodes (71 days identified as AD by SPR, vs 81 by TAU), as it is less affected by interferences with local dust sources. The mean annual contribution of AD was lower with the TAU method than with SPR (2.7 vs 3.5 ± 1.5 μg/m(3)). The SPR and TAU AD time series were correlated with daily aluminum levels (a known tracer of AD), as well as with an AD source identified by the Positive Matrix Factorization (PMF) receptor model. Higher r(2) values were obtained with the SPR method than with TAU in both cases (r(2) = 0.72 vs 0.56, y = 0.05x vs y = 0.06x with aluminum levels; r(2)=0.79 vs 0.43, y = 0.8x vs y = 0.4x with the PMF source). We conclude that the SPR method is more adequate from an EU policy perspective (justification of DLV exceedances) due to the fact that it is more conservative than the TAU method. Based on our results, the TAU method requires adaptation of the thresholds in the algorithm to refine detection of low-impact episodes and avoid misclassification of local events as AD.     

Dielectrical,microstructural and flow properties of sauce model systems based on starch,gums and salt

The dielectric properties of salted systems based on different hydrocolloids (native or modified starches, or on ι, λ, or κ carrageenan) as models for microwaveable white sauces were studied. Microstructural and rheological properties were also studied to better understand the dielectric behaviour.     

Secular trends in growth in male adolescents: height and weight gains, nutritional state and relation with education

This work aimed at characterizing the modifications in adolescents nutritional status, growth evolution and education along time and the correlation with the height, weight and body mass index. Data came from 2616 male adolescents soldiers between 17 and 19 years old enlisted for Armed Services in the city of Vi?osa-Minas Gerais, Brazil, between 1995 and 2004. There was a positive secular trend for height and weight, with a 4cm and 3kg median increment, respectively, along time. There was a reduction from 28.0% to 11.6% on the prevalence of short stature in the period. It was estimated positive correlation (p < 0.05) between education and stature, weight and BMI. The prevalence of weight excess (risk of overweight and overweight) increased from 7.1% (1995) to 9.1% (2004). Although it was observed positive secular trend for stature and weight, it was not sufficient to reach the median of the National Center for Health Statistics/Center for Disease Control and Prevention. Weight excess and short stature prevalence must be monitored, being necessary the implementation of measures that focus to prevent these disturbance and aim at reaching or maintaining an adequate nutritional state for future generations.     

Chemical composition, starch digestibility and antioxidant capacity of tortilla made with a blend of quality protein maize and black bean

Tortilla and beans are the basic components in the diet of people in the urban and rural areas of Mexico. Quality protein maize is suggested for tortilla preparation because it presents an increase in lysine and tryptophan levels. Beans contain important amounts of dietary fiber. The objective of this study was to prepare tortilla with bean and assesses the chemical composition, starch digestibility and antioxidant capacity using a quality protein maize variety. Tortilla with bean had higher protein, ash, dietary fiber and resistant starch content, and lower digestible starch than control tortilla. The hydrolysis rate (60 to 50%) and the predicted glycemic index (88 to 80) of tortilla decreased with the addition of bean in the blend. Extractable polyphenols and proanthocyanidins were higher in the tortilla with bean than control tortilla. This pattern produced higher antioxidant capacity of tortilla with bean (17.6 μmol Trolox eq/g) than control tortilla (7.8 μmol Trolox eq/g). The addition of bean to tortilla modified the starch digestibility and antioxidant characteristics of tortilla, obtaining a product with nutraceutical characteristics.     

A two-scale Weibull approach to the failure of porous ceramic structures made by robocasting: Possibilities and limits

This paper introduces our approach to modeling the mechanical behavior of cellular ceramics, through the example of calcium phosphate scaffolds made by robocasting for bone–tissue engineering. The Weibull theory is used to deal with the scaffolds’ constitutive rods statistical failure, and the Sanchez-Palencia theory of periodic homogenization is used to link the rod- and scaffold-scales. Uniaxial compression of scaffolds and three-point bending of rods were performed to calibrate and validate the model. If calibration based on rod-scale data leads to over-conservative predictions of scaffold's properties (as rods’ successive failures are not taken into account), we show that, for a given rod diameter, calibration based on scaffold-scale data leads to very satisfactory predictions for a wide range of rod spacing, i.e. of scaffold porosity, as well as for different loading conditions. This work establishes the proposed model as a reliable tool for understanding and optimizing cellular ceramics’ mechanical properties.     

Atmospheric plasma spraying coatings from alumina–titania feedstock comprising bimodal particle size distributions

In this work, Al₂O₃–13 wt% TiO₂ submicron-nanostructured powders were deposited using atmospheric plasma spraying. The feedstocks were obtained by spray drying two starting suspensions of different solids content, prepared by adding nanosized TiO₂ and submicron-sized Al₂O₃ powders to water. The spray-dried granules were heat-treated to reduce their porosity and the powders were fully characterised in both untreated and thermally treated state. Comparison with two commercial feedstocks was carried out. Characterisation allowed a temperature for the thermal treatment to be chosen on the basis of the sprayability of the feedstock and the preservation as much as possible of the submicron-sized structure of the unfired agglomerates.Optimisation of the deposition conditions enabled the reconstituted powders to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterised by SEM, was mostly formed by a matrix of fully molten particles where the presence of semi-molten feedstock agglomerates was also observed.Moreover, microhardness, toughness, adhesion and tribological behaviours were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allows controlling the coating quality and properties. In general, good mechanical properties were obtained using a feedstock comprising a binary mixture of submicrometric Al₂O₃ and nanometric TiO₂ particles in the spray-dried powder.