Wednesday, 31 August 2016

Lipid characteristics of dry-cured “Tocino” during the manufacturing process. Effects of salting intensity and ripening temperature

Journal of Food Composition and Analysis, 52 (2016) 33–43

The fatty acid composition, the lipid characteristics and the colour parameters of Tocino, a salted and ripened meat product made from subcutaneous backfat from pig, were studied throughout manufacturing of the product. The effects of the ripening temperature and of the duration of the salting process were also studied. Ripening process caused a significant (P < 0.001) decrease in the total and some individual polyunsaturated fatty acids (C18:2n-6, C18:3n-3, C20:2n-6, C20:3n-6, C20:4n-6, and C20:3n-3), particularly in the polar lipid fraction (total polyunsaturated fatty acids descended from 13.6 to 3.5% of total methyl esters). Increased ripening temperature (from 8 to 12 °C) and longer duration of salting (from 2 to 4 days) caused a significantly greater decrease in the content of polyunsaturated fatty acids. The nutritional and health index values indicated that Tocino is not a healthy product. During the ripening stage, Tocino underwent moderate lipolysis and very intense lipid oxidation (final values of 3.57–5.09 mg KOH/g of fat and 0.84–1.16 mg malondialdehyde/kg). Increasing the ripening temperature significantly increased (P < 0.001) both lipolysis and fat oxidation, while increasing the duration of salting only had a significant positive effect on oxidation processes. Longer ripening times led to a significant increase (P < 0.001) in the b* values (from 8.81 to 18.7–23.7) and significant decreases in the a* (from 7.10 to −3.31 – −4.04) and L* (from 81.5 to 66.4–70.2) values.

Tuesday, 30 August 2016

Effect of high pressure treatment on the structural, mechanical and rheological properties of glucomannan gels

Food Hydrocolloids, 60 (2016) 437–444

The influence of high hydrostatic pressure (HHP) of 100 (C100), 200 (C200), 400 (C400) and 600 MPa (C600) on the structural, physicochemical, and thermo-rheological properties of aqueous glucomannan dispersions (AGD) was studied. Each AGD was prepared with a 5% concentration of deacetylated glucomannan (GM) at pH = 11 for use in the preparation of restructured fish products. The control (0 MPa) AGD (C0) exhibited a partially crystalline GM network with a glass transition temperature (Tg) of ∼75 °C. C0 gels at 25 °C were rigid, with high breaking force (BF), fracture constant (Kf) and complex modulus (G*) and low tanδ values due to the large number of physical junctions produced by complete deacetylation of the GM chains. This structural response was reflected in high water binding capacity (WBC) and colour (L*) and low cooking loss (CL). Specifically, 200 MPa reduced close packing ability in the crystalline regions, evidenced in the lower Tg∼65 °C and resulting in lower gel strength (S), Kf, G* and a higher viscous component (high tanδ), thus reducing the L* value. Conversely, 600 MPa increased the degree of cross-linking in C600, reinforcing the number and extent of crystalline regions, resulting in the broadening of the O–H stretching band in the FT-IR spectrum and producing a thermoset physical network with no glass transition region. Thus, C600 gel was firmer (higher G*) with greater S, and less flexible (lower strain amplitude-γmax). Consequently, depending on the textural properties desired in the final restructured fish product, the most appropriate pressure would be 200 MPa for softer final gels and 600 MPa for firmer and less deformable gels.

Wednesday, 24 August 2016

Combined alkali and hydrothermal pretreatments for oat straw valorization within a biorefinery concept

Bioresource Technology

The aim of this work was the evaluation of lime pretreatment combined or not with previous step of autohydrolysis for oat straw valorization. Under selected conditions of lime pretreatment, 96% of glucan and 77% of xylan were recovered and 42% of delignification was achieved. Xylose fermentation to ethanol by metabolic engineered Saccharomyces cerevisiae (MEC1133) strain improved the ethanol production by 22% achieving 41 g/L. Alternatively, first step of autohydrolysis (S0=4.22) allowed a high oligosaccharides recovery (68%) and subsequent lime pretreatment attained a 57% of delignification and 99% of glucan to glucose conversion. Oat straw processed by autohydrolysis and lime pretreatment reached the maximal ethanol concentration (50 g/L). Both strategies led to oat straw valorization into bioethanol, oligosaccharides and lignin indicating that these pretreatments are adequate as a first stage within an oat straw biorefinery.

Tuesday, 23 August 2016

Production and characterization of a novel distilled alcoholic beverage produced from blueberry (Vaccinium corymbosum L.)

Fruits, 2016, vol. 71(4), 215-220

The cultivation of underutilized berries and the process production of high-value-added products, such as fruit-based spirits, could have a beneficial effect on the economy of disadvantaged rural mountain areas of Spain. However, production of a distilled alcoholic beverage from the blueberry has not been reported before. The pulp of blueberries var. Bluecrop was fermented with Saccharomyces cerevisiae IFI83, distilled by using a steam drag distillation system and the volatile compounds were determined by gas chromatography. In the distillate obtained, the mean concentrations of ethanol (45.3 mL 100 mL-1 distillate), volatile substances (317.1 g hL-1 absolute alcohol) and methanol (261.0 g hL-1 absolute alcohol) were in accordance with the specifications that the European Council (Regulation 110/2008) fixed for these compounds. In addition, the ratios [3-methyl-1-butanol/2-methyl-1-propanol] and [2-methyl-1-propanol/1-propanol] were 2.60 and 1.34, respectively, indicating that the distilled alcoholic beverage has a good organoleptic quality. The results suggest that blueberry can be successfully used for the production of a novel spirit with a good sensory quality that is safe for the consumers.

Thursday, 4 August 2016

Loss of Gravitropism in Farnesene-Treated Arabidopsis Is Due to Microtubule Malformations Related to Hormonal and ROS Unbalance


Mode of action of farnesene, a volatile sesquiterpene commonly found in the essential oils of several plants, was deeply studied on the model species Arabidopsis thaliana. The effects of farnesene on the Arabidopsis root morphology were evaluated by different microscopic techniques. As well, microtubules immunolabeling, phytohormone measurements and ROS staining helped us to elucidate the single or multi-modes of action of this sesquiterpene on plant metabolism. Farnesene-treated roots showed a strong growth inhibition and marked modifications on morphology, important tissue alterations, cellular damages and anisotropic growth. Left-handed growth of farnesene-treated roots, reverted by taxol (a known microtubule stabilizer), was related to microtubule condensation and disorganization. As well, the inhibition of primary root growth, lateral root number, lateral root length, and both root hairs length and density could be explained by the strong increment in ethylene production and auxin content detected in farnesene-treated seedlings. Microtubule alteration and hormonal unbalance appear as important components in the mode of action of farnesene and confirm the strong phytotoxic potential of this sesquiterpene.

Tuesday, 2 August 2016

Carbohydrate Polymers, 146 (2016) 20–25

Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicelluloses (as soluble saccharides) from a solid phase mainly made up of cellulose and lignin. The liquid phase was dehydrated, and the resulting solids (containing pentoses as well as poly- and oligo- saccharides made up of pentoses) were dissolved and reacted in media containing an Acidic Ionic Liquid (1-butyl-3-methylimidazolium hydrogen sulfate) and a co-solvent (dioxane). The effects of the reaction time on the product distribution were studied at temperatures in the range 120–170 °C for reaction times up to 8 h, and operational conditions leading to 59.1% conversion of the potential substrates (including pentoses and pentose structural units in oligo- and poly- saccharides) into furfural were identified.

Monday, 1 August 2016

Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe

Science of The Total Environment 562, 2016, 179–190

We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10–144 µg kg− 1, reaching up to 41 and 145 mg kg− 1 for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed.