Multivariate analysis for the differentiation of sparkling wines elaborated from autochthonous Spanish grape varieties: volatile compounds, amino acids and biogenic amines

The aim of this work was to focus on the study of the volatile composition of white and rosé base wines elaborated from different autochthonous grape varieties in Spain (Verdejo, Viura, Malvasía, Albarín, Godello, Prieto Picudo and Garnacha) and the evolution of the sparkling wines elaborated from them following the “champenoise” method. The amino acids and biogenic amines were also studied. Multivariate analyses (factorial and stepwise discriminant) were carried out to study the influence of these compounds all together. Base and sparkling wines from Albarín, Verdejo, Godello and Prieto Picudo were the richest in most of the volatile compounds analyzed, especially of ethyl esters and alcohol acetates, compounds that contribute to the fruity aroma of wines. During the aging on lees in the bottle of sparkling wines, an increase in branched ethyl esters, ethyl lactate and γ-butyrolactone, and a decrease in terpenes (mainly citronellol and geraniol) were observed. In general, the levels of biogenic amines in all the sparkling wines studied were very low, which does not represent a negative effect on their quality and safety.     

As (V) biosorption in an aqueous solution using chemically treated lemon (Citrus aurantifolia Swingle) residues

The use of biosorbents to remove metals and metalloids from contaminated water systems has gained great usage in various parts of the world. The objective of the current study was to test lemon peels as biosorbents for As (V). Lemon peels were chemically characterized and arsenic contact experiments were performed to determine the adsorption capacity of the peels using different empirical models. The model that fit the experimental data was the Lagergren empirical model with a correlation coefficient of R= 0.8841. The results show that lemon peels were able to retain 474.8 μg of As (V)/g of biosorbent. PRACTICAL APPLICATION: Lemon agro-industrial waste can be useful in the removal of heavy metals, such as arsenic, from aqueous media.     

Enzymatic treatments as alternative to produce chitin fragments of low molecular weight from Alternaria alternata

Chitin and its oligosaccharides are involved in the plant defense response against fungal pathogens. In most studies, these molecules come from crustacean shell, and there are scarce studies on the use of fungal chitin. Usually the extraction of chitin is by alkaline treatments, which affect the acetylation degree (DA), and the obtaining of oligosaccharides of low molecular weight; so the use of enzymes is proposed as an alternative treatment to obtain chitin oligosaccharides from fungi. The objective of this work was to characterize the chitin fragments of Alternaria alternata extracted by alkaline and enzymatic treatments. The chitin extracted was ultrasonicated and ultrafiltrated to produce chitin fragments. Enzymatic treatments decreased the protein content to 29%, and the bands corresponding to β-glucans decreased when β-1,3-glucanase was applied. Fragments smaller than 1 kDa, DA of 76.7%, and 35.4 μg glucosamine/mg dry weight were obtained by enzymatic treatments. The enzymatic treatments show promising results to extract chitin fragments from A. alternata without severely affect the DA of the molecule. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47339.     

Differential synthesis of fermentative aroma compounds of two related commercial wine yeast strains

The specific impact of the yeast strain on the wine flavour and aroma has not been well characterised yet because this effect is usually combined with other variables during the winemaking. In this study, the contribution to wine flavour of two Saccharomyces cerevisiae strains widely used in wine production, VIN13 and EC1118, was evaluated after fermentation at 15 °C. Chemical defined grape juice media fermented with the EC1118 strain showed higher solvent, fatty and pineapple aroma attributes, while that fermented with the VIN13 strain exhibited higher banana, fruity, yeasty and green attributes. Sensorial and chemical analyses evidenced that the production of flavour-active compounds is significantly affected by the yeast strain, as well as by the temperature of fermentation, as shown by comparing the former data with those from fermentations carried out at 28 °C under identical culture conditions.     

Changes in the color components and phenolic content of red wines from Vitis vinifera L. Cv. “Tempranillo” during vinification and aging

Changes in phenolics and color components during vinification and aging of Tempranillo wines were studied. Different phenolics display different diffusion into the must, and with the exception of proanthocyanidins and acetyl-glucoside anthocyanins, with maximum concentration at the end of postmaceration, the rest of the unacylated and coumarated anthocyanins, monomeric flavanols, and hydroxycinnamic acids reached their maximum at the end of alcoholic fermentation. This resulted in a significant increase in both wine color and stable color, mainly due to the formation of copigmentation complexes, although polymeric pigment formation was also important. Malolactic fermentation produced a significant decrease in flavonoid content while nonflavonoid concentrations were maintained, prompting a considerable loss in wine color, despite the dramatic increase in bisulfite-stable color. Wine oak aging did not produce any significant change in the studied parameters, while bottle aging reduced the level of monomeric anthocyanins and flavanols, and hydroxycinnamic acids. However, wine color remained stable due to a significant increase in stable color. Polymerization reactions of anthocyanins prevailed over pigment degradation reactions, and copigmentation was still relevant after 2 years of bottle aging.     

Physicochemical and Biochemical Characterization of Starch Granules Isolated of Pigmented Maize Hybrids

In this study, the morphological and physicochemical of pigmented maizes as well as the initial characterization of the corresponding starch granule enzymes are described. Starch granules were isolated from blue, black, and white maize. They were analyzed using scanning electron microscopy, particle size distribution, pasting characteristics, sorption isotherms, differential scanning calorimetry, and two‐dimensional gel electrophoresis. The morphology of the starch granules of pigmented maizes was different from the granules of white maize; the pattern was related to the endosperm type of these varieties. The average starch granule size was higher for black than for white and blue maizes. The average gelatinization temperature was similar in the three starches, but the pigmented maizes had higher gelatinization enthalpy; black maize starch showed the lowest enthalpy of retrogradation. These results indicated that the starches from the three maizes analyzed had different organization level. Black maize starch showed the highest peak viscosity followed by white and blue maize starches. In the gel electrophoresis three starch granules presented one main spot at pI of 5 and MW of 60 kDa that corresponds to the granule‐bound starch synthase. Blue and white starches presented some spots near 97 kDa at pI of 5.3–5.7 (white maize) and 5.1–5.5 (blue maize), spots that were not observed for black maize starch. The morphological and physicochemical characteristics of maize starch are related to the enzymes involved in its biosynthesis.     

Alumina Nucleation,Growth Kinetics,and Morphology: A Review

The reaction between aluminum and the dissolved oxygen in liquid steel yields the precipitation of alumina crystals with characteristic morphologies and size distributions. Alumina precipitation and growth involve a wide spectrum of time, length, velocity, and thermodynamic supersaturation scales throughout the refining processes. The smallest length and time scales are those quantifying the nucleation kinetics and the initial growth at the highest supersaturation. Further growth and crystal morphology depend on the concentration of surface tension elements which inhibit the crystal's faces suffering further modifications due to washing effects provided by turbulent flows. This step involves longer time, velocity, length, and moderate supersaturations. The final step involves the growth of alumina inclusions through collision–agglomeration–sintering, and capillary processes on the surfaces of argon bubbles under low supersaturations. Jumps of supersaturation, due to late aluminum additions or steel reoxidation, lead to alumina crystals changing their morphology to dendritic-type growth. The present contribution reviews each one of these kinetic phenomena closing with the consequences that alumina precipitation has on the continuous casting process. The content of this review is useful to practitioners and theorists alike.