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Beer quality generally diminishes over time as staling compounds accumulate through various oxidation reactions. Here, we show that refermentation, a traditional practice where Saccharomyces cerevisiae cells are added to beer prior to bottling, diminishes the accumulation of staling aldehydes. However, commonly used beer yeasts only show a limited lifespan in beer. Using high-throughput screening and breeding, we were able to generate novel S. cerevisiae hybrids that survive for over a year in beer. Extensive chemical and sensory analyses of the two most promising hybrids showed that they slow down the accumulation of staling aldehydes, such as furfural and trans-2-nonenal and significantly increased beer flavor stability for up to 12 months. Moreover, the strains did not change the original flavor of the beer, highlighting their potential to be integrated in existing products. Together, these results demonstrate the ability to breed novel microbes that function as natural and sustainable anti-oxidative food preservatives. ispartof: FOOD CHEMISTRY vol:398 ispartof: location:England status: published

ispartof: DYES AND PIGMENTS vol:199 status: published

Animal proteins are widely used because of their good techno-functional (e.g. emulsification) properties. However, the large ecological impact of animal-derived proteins is often debated and therefore alternatives are evaluated in which animal proteins with increased functionality are employed. Amyloid fibrils are a distinct type of protein fibrils characterized by an intermolecular cross β-sheet structure, mostly studied because of concerns regarding their role in certain human diseases. However, they have also been detected in processed food proteins such as heated ovalbumin (OVA) and other egg proteins. Previous work also mentioned superior emulsification properties of amyloid-like fibrils. Here, the effect of different shear conditions during the emulsification of oil in water emulsions stabilized by heated OVA was investigated. Emulsification with intensive shear treatment (using both an ultra-turrax and a microfluidizer) resulted in submicron sized droplets, whilst ultra-turrax only gave rise to rapidly creaming emulsions (>10 μm). Thioflavin T (ThT) fluorescence, used as an indicator of cross β-sheets, did significantly increase for submicron emulsions, whereas supermicron emulsions showed a similar fluorescence as the aqueous phase used for emulsification. The increase in ThT fluorescence in submicron emulsions was in line with a higher amount of larger fibrillar structures, which showed high ThT fluorescence, measured using size exclusion-HPLC and transmission electron microscopy images. Similar observations were also made for unheated OVA, suggesting that high-shear emulsification induced amyloid-like fibril formation. In contrast, shearing of aqueous solutions without the creation of interfaces did not show increased fibril formation. Therefore, it is claimed that the large specific surface area induced amyloid-like fibril formation or maturation as a result of a better interaction between hydrophobic amyloid-like fibril fragments. In this work, we were able to characterize the protein fibrillar structures present in emulsions by considering commonly used techniques for the study of fibril formation. This creates opportunities towards the implementation of these protein mixtures in food applications.

Cellulose acetate (CA) is an attractive membrane polymer for CO2 capture market. However, its low CO2 permeability hampers its application as part of a membrane for most relevant types of CO2 containing feeds. This work investigates the enhancement of CA separation performance by incorporating ionic liquid-like pendants (1-methylimidazol, 1-methylpyrrolidine, and 2-hydroxyethyldimethylamine (HEDMA) on the CA backbone. These CA-based polyelectrolytes (PEs), synthesised by covalent grafting of cationic pendants with anion metathesis, were characterised by NMR, FTIR, DSC/TGA, and processed into thin-film composite membranes. The membrane performance in CO2/N2 mixed-gas permeation experiments shows a decrease in CO2 and N2 permeability and an initial decrease and then gradual increase in CO2/N2 selectivity with increasing HEDMA content. The amount of HEDMA attached to the CA backbone determines overall separation process in bifunctional PEs. This indicates that the hydroxy-substituted cationic pendants alter interactions between PEs network and permeating CO2 molecules, suggesting possibilities for further improvements. ispartof: CARBOHYDRATE POLYMERS vol:255 ispartof: location:England status: published

Different perylene-3,4:9,10-bis(dicarboximide) (abbreviated as perylenebisimides, or simply PBI) compounds (MT-PBI, DT-PBI, MP-PBI and DP-PBI) with thienyl and phenyl substituents at the bay position were prepared to study the effect of substitution on the photophysical properties, especially the intersystem crossing (ISC) efficacy. We found that the derivative with a monothienyl substituent (MT-PBI) shows efficient ISC (singlet oxygen quantum yield ΦΔ = 72%) and longer triplet state lifetime (τT = 64.4 μs) as compared to reference compounds (derivative with monophenyl substituent at bay position, MP-PBI, ΦΔ = 23% and τT = 48.5 μs). Theoretical computations reveal that the ISC efficiency is dependent on the magnitude of the spin orbit couplings (SOC) between the singlet and triplet excited states, and the SOC matrix element is up to 2 cm−1 for compound showing the highest ISC efficiency. Femtosecond transient absorption spectra show the ISC rate constant of 8 × 109 s−1 for MT-PBI, and no charge transfer exists. Photo-driven electron transfer was observed with the PBI derivatives in the presence of sacrificial electron donor triethanolamine (TEOA), and reversible formation of PBI radical anion (PBI−•) was observed, which shows absorption in the range of 600 nm–800 nm and 900 nm–1000 nm. Delayed fluorescence (P-type) in MT-PBI was also observed (τT = 31.0 μs). These finding are useful for the design of PBI-derived heavy atom-free compounds to be used as triplet photosensitizers.

Biological studies on the importance of carbohydrate moieties in tissue engineering have incited a growing interest in the application of polysaccharides as scaffolds over the past two decades. This review provides a perspective of the recent approaches in developing polysaccharide scaffolds, with a focus on their chemical modification, structural versatility, and biological applicability. The current major limitations are assessed, including structural reproducibility, the narrow scope of polysaccharide modifications being applied, and the effective replication of the extracellular environment. Areas with opportunities for further development are addressed with an emphasis on the application of rationally designed polysaccharides and their importance in elucidating the molecular interactions necessary to properly design tissue engineering materials. ispartof: CARBOHYDRATE POLYMERS vol:205 pages:601-625 ispartof: location:England status: published

Gas cell stabilization in dough by its aqueous phase constituents is arguably more important in non-wheat than in wheat dough due to weaker protein networks in the former. Dough liquor (DL), a model for the dough aqueous phase, was isolated from fermented wheat, rye, barley, and oat doughs by ultracentrifugation. DL composition (protein, lipid, arabinoxylan, β-glucan) and air/water interfacial functionality [foaming, viscosity, surface tension, surface dilatational modulus (E)] were related to bread quality. Poor foaming and low E of wheat DL were ascribed to lipids and proteins co-occurring at the interface. Nonetheless, the presence of a gluten network resulted in high-quality wheaten breads. Homogeneous and heterogeneous crumb structures of rye and barley breads, respectively, were attributed to high and low E values of their respective DLs. High lipid content and low surface tension of oat DL indicated a lipid-dominated interface, which may explain the heterogeneous crumb structure of oat breads. ispartof: FOOD CHEMISTRY vol:264 pages:126-134 ispartof: location:England status: published

The thermo-active serine peptidase aqualysin 1 (Aq1) of Thermus aquaticus was applied in bread making to study the relative contribution of thermoset gluten to bread crumb texture. Aq1 is active between 30 °C and 90 °C with an optimum activity temperature of around 65 °C. It is inhibited by wheat endogenous serine peptidase inhibitors during dough mixing and fermentation and starts hydrolyzing gluten proteins during baking above 80 °C when the enzyme is no longer inhibited and most of the starch is gelatinized and contributes to structure formation. Aq1 activity reduced the molecular weight of gluten proteins and significantly increased their extractability in sodium dodecyl sulfate containing medium. While it had no impact on the specific bread volume and only limited impact on hardness, cohesiveness, springiness, resilience and chewiness, it impacted bread crumb coherence. We conclude that starch has a greater impact on crumb texture than thermoset gluten. ispartof: FOOD CHEMISTRY vol:264 pages:118-125 ispartof: location:England status: published

Polysaccharides, and especially alginate, can be useful for self-healing of cracks in concrete. Instead of weak electrostatic bonds present within calcium alginate, covalent bonds, by methacrylation of the polysaccharides, will result in mechanically stronger superabsorbent polymers (SAPs). These methacrylated alginate chains as backbone are combined with two acrylic monomers in a varying molar fraction. These SAPs show a moisture uptake capacity up to 110% their own weight at a relative humidity of 95%, with a negligible hysteresis. The swelling capacity increased (up to 246 times its own weight) with a decreasing acrylic acid/2 acrylamido-2-methylpropane sulfonic acid ratio. The SAPs also showed a thermal stability up to 200 degrees C. Interestingly, the SAP composed of alginate and acrylic acid exerted a very limited decrease in compressive strength (up to 7% with addition of 1 wt% SAP) rendering this material interesting for the envisaged self-healing application. The authors would like to thank the FWO (Research Foundation Flanders) for project funding (3G019012, Effect of tunable hydro gels on concrete microstructure, moisture properties, sealing and self-healing of cracks). The authors would like to acknowledge the group of Peter Adriaensens and especially Gunter Reekmans for the calculation of the degree of methacrylation of algMOD (Organic and Bio-polymer Chemistry Department, UHasselt).

The essential oils, isolated by hydrodistillation and distillation-extraction, from the aerial parts of different populations of Pterospartum tridentatum collected during the flowering phase, at different locations in Portugal, were analysed by GC and GC-MS. All the P. tridentatum populations studied afforded a yellowish oil in a yield 0.05% (v/w). cis-Theaspirane (2-14%), trans-theaspirane (2-17%) and octen-3-ol (2-37%) were, in variable amounts, the dominant components of the oils. Cluster analysis of the essential oil compositions from the nine populations studied, confirmed a major chemical variability. (c) 2006 Elsevier Ltd. All rights reserved.

Initially exploited in chemistry and physics, high-pressure technology has gained importance in various fields. Flavonoids, namely naringin and naringenin, from citrus, are functional chemicals with important properties in the fields of healthcare, food and agriculture. Naringin, the principal bitter flavonone glycoside and the primary bitter component in grapefruit juice, can be hydrolysed by naringinase into tasteless naringenin. The temperature of 303 K was ideal for maximizing the activity of the naringinase at 160 MPa when compared to atmospheric pressure. The pressure had a positive effect on the reaction rate, with a value of - 15.0 1.8 cm(3) mol(-1) for the activation volume. Kinetic parameters, k(m) and V-max for naringinase were evaluated, the maximum initial rate at 160 MPa (V-max = 2.7 mM min(-1)) was higher than that at atmospheric pressure (V-max = 0.06 mM min(-1)). This is a promising result for future application of enzymatic hydrolysis of naringin at high pressure, in the citrus juice industry. @ 2006 Elsevier Ltd. All rights reserved.

The usual methods for determination vitamin K are laborious. With the aim of replace them by a simpler method that requires fewer solvents, lower analytical levels and allows reporting of results in a smaller period of time, a procedure based on solid-phase microextraction (SPME) and gas chromatography with flame ionization detector (GC-FID) was developed. This method was used to analyse vitamin K in green tea leafs and infusions from nine brands of green tea commercialised in Portugal. The best analytical conditions were obtained using PDMS 7 mu m fibre using immersion extraction at 40 degrees C, for 45 min and 1300 rpm. The linear range for vitamins K1 and K2 was defined. The detection limits obtained with PDMS fibre and GC/FID were 0.16 and 0.07 mg/L for vitamins K1 and K2, respectively. In all analysed infusions the concentration of vitamin K was lower than the detection limit of the developed method, however, the concentration of vitamin K1 present in tea leafs was between 120 and 625 mu g/100 g. (c) 2005 Elsevier Ltd. All rights reserved.