Influence of Casein Hydrolysates and Yeast on the Rheological Properties of Wheat Dough.

The influence of casein hydrolysates (CHs) and yeast on the viscoelasticity of wheat dough at 25 °C were analysed. Three wheat doughs were studied: the unyeasted dough (UYD), the unyeasted dough with CHs (UYD-C) and the yeasted dough (YD). The characteristic parameters in the linear viscoelastic range (LVER) were analysed by stress sweep at 6.3 rad/s: UYD-C dough exhibited higher values of stress (σmax) and strain (γmax) amplitudes, and softer gel network (lower complex modulus, G*) comparing with UYD dough. The oscillatory data suggest that CHs would work as (energy and time) stabilising-agents based on the greatest reticular energy (E parameter) and the lowest frequency dependence of phase angle (δ) at the low frequency range. The rotatory tests show that CHs may act as shear thinning agents in the gluten-starch network, facilitating the solid-fluid transition at the yield point (UYD-C dough). The yeasted dough (YD) exhibited a more shear sensitive structure, evidenced in the highest influence of frequency on the elastic (G') and viscous (G″) parameters, and gel to sol transition at 0.23 rad/s was observed.

Xylitol production in immobilized cultures: a recent review.

Xylitol is a pentahydroxy sugar alcohol coming from xylose with many applications in the food and pharmaceutical industries as a low caloric sweetener suitable for diabetics and as an active ingredient in several biomedical applications. The microbial bioproduction of xylitol from natural xylose coming from lignocellulosic materials appears a sustainable and a promising alternative to chemical synthesis, which works at stronger reaction conditions and generates undesirable co-products which must be removed. There are several reviews that study the metabolic pathways in wild and transformed xylitol producing yeasts and the culture conditions that enhance xylitol accumulation, which are mainly related to the need of microaerobiose for the best producing wild yeasts. Nevertheless, there are relatively few studies focusing on the engineering aspects related to scalable systems and bioreactors that could result in a final industrial stage. This review explores recent advances on xylitol production using immobilized systems, which have been proposed to facilitate the reuse of the biocatalyst for extended periods and the main types of bioreactors available assayed for this purpose.

Ferulic acid transformation into the main vanilla aroma compounds by Amycolatopsis sp. ATCC 39116.

The wild strain Amycolatopsis sp. ATCC 39116 was explored in ferulic acid-based media to produce naturally the aroma components of the cured vanilla pod, namely vanillin,vanillic acid, and vanillyl alcohol. Other phenolic compounds(4-vinyl guaiacol, guaiacol, and protocatechuic acid) were also evaluated. The influence of medium composition,fermentation technology (batch or fed-batch), supplementation with vanillic acid, and inoculum concentration on ferulic acid biotransformation were evaluated. The results postulate the initial concentration of cell mass as the variable with the strongest impact on ferulic acid metabolization under the studied conditions. The highest amounts of vanillin and vanillic acid were achieved at intermediate values of cell mass.Vanillyl alcohol and protocatechuic acid were more closely linked to high cell mass concentrations. Conversely, 4-vinyl guaiacol reached its highest amount at the lowest amount of cell mass. Guaiacol was not detected in any case. Therefore,the initial cell concentration must be considered a critical parameter when using Amycolaptosis sp. ATCC 39116 for the production of vanillin and related compounds.

Production and characterization of distilled alcoholic beverages obtained by solid-state fermentation of black mulberry (Morus nigra L.) and black currant (Ribes nigrum L.).

The present study was conducted to appraise the potential of black mulberry and black currant to be used as fermentation substrates for producing alcoholic beverages obtained by distillation of the fruits previously fermented with Sacchromyces cerevisiae IFI83. In the two distillates obtained, the volatile compounds that can pose health hazards are within the limits of acceptability fixed by the European Council (Regulation 110/2008) for fruit spirits. However, the amount of volatile substances in the black currant distillate (121.1 g/hL absolute alcohol (aa)) was lower than the minimum limit (200 g/hL aa) fixed by the aforementioned regulation. The mean volatile composition of both distillates was different from other alcoholic beverages such as four commercial Galician orujo spirits, Portuguese bagaceiras, and two distillates obtained from fermented whey and blackberry. The results obtained showed the feasibility for obtaining distillates from fermented black mulberry and black currant, which have their own distinctive characteristics.

Development of a factorial design to study the effect of the major hemicellulosic sugars on the production of surface-active compounds by L. pentosus.

Nowadays, there are no studies about the role of the major hemicellulosic sugars on the production of surface-active compounds by Lactobacillus pentosus, although it was demonstrated that the activity of these compounds can be related to the agricultural residue from which they come, as the sugar solutions obtained from different agricultural residues contain different types and ratios of hemicellulosic sugars. Therefore, in this work, an incomplete factorial design was employed to test the relationship between the type and the ratio of hemicellulosic sugars present in hydrolysates from agricultural residues and the activity of surface-active compounds (cell-bond biosurfactants and extracellular bioemulsifiers) produced by L. pentosus. This design allowed us to establish models (that include linear, interaction, and quadratic terms) between dependent and independent variables. The independent variables used and their variation limits were as follows: glucose concentration (0-10 g L(-1)), xylose concentration (5-15 g L(-1)), and arabinose concentration (0-10 g L(-1)), whereas the 13 dependent variables studied were based on the measurement of surface tension and emulsifying capability. After the study, it was found that the emulsifier capacity of extracellular bioemulsifiers produced by L. pentosus increases at high glucose and xylose concentrations, with glucose concentration as the most influential variable in the range studied. However, the increase of glucose in the absence of xylose produced biosurfactants with low surface activity, with, in this case, the xylose concentration as the most influential variable. Taking into account the xylose/glucose ratio, the best results were obtained with xylose/glucose ratios around 1.5-3.5, which can be found in hemicellulosic hydrolysates from trimming vine shoots or grape marc hydrolysates.

Simulating washoff of Cu-based fungicide sprays by using a rotating shear device.

Foliar washoff causes a loss of copper-based pesticides sprayed on crops, leading to an increase in the number of applications and contamination of the soil with Cu. In field studies, the variables that determine the amount of Cu loss are difficult to control. An experimental setup based on a rotating shear device (RSD) was used to estimate the influence of physical factors in the loss of Cu due to washoff of three copper-based fungicides: copper oxychlorhide (CO), Bordeaux mixture (BM), and a mixture of copper oxychlorhide and propylene glycol (CO-PG). Full factorial designs were used to model the loss of Cu from fungicides sprayed on the polypropylene surface of the RSD. Variables in the experiments were rotation speed, wash water volume, and fungicide dose. Good reproducibility was obtained for Cu loss, with a coefficient of variation less than 8%. Mean Cu losses were 27.0, 33.0, and 13.5% of the copper applied in fungicide for the BM, CO, and CO-PG, respectively. Empirical equations were obtained to calculate Cu losses from the rotation speed, wash water volume, and dose, as well as their interactions. CO losses were consistent with a model of particle detachment in which such losses depended on a threshold boundary shear stress required to initiate particle motion. Also, percent CO losses were found to be significantly correlated with the linear momentum at the surface boundary. The momentum values obtained in the RSD tests were similar to those estimated for a rainfall event of 20 mm h(-1) lasting 10 min. The most important mechanism in the loss of CO was the erosion of Cu-bearing particles.

Treatment of an acid soil with bentonite used for wine fining: effects on soil properties and the growth of Lolium multiflorum.

When used to fine wines, bentonite acquires a protein load that makes it a potentially useful fertilizer. Other properties of bentonite are also potentially useful for soil amendment. In the work described in this paper, waste bentonite from a winery was applied to an acid soil, and its effects on soil properties and on the growth of Lolium multiflorum were evaluated. Soil N, K, and P contents all increased, as did pH and cation exchange capacity. Biomass production increased as the dose of bentonite increased up to 5 g kg(-1), decreasing at larger doses (possibly as a result of falling potassium/magnesium ratio and increasing electrical conductivity). Environmental drawbacks of waste bentonite include its high soluble copper content, although its conversion in the soil to less soluble forms reduces its potential phytotoxicity. The copper, manganese, and zinc contents of the ryegrass crop were low.