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Enzymatic Modification of Polyvinylpolypyrrolidone (PVPP) for Improved Adsorption of Proteins and Polyphenols Causing Haze in Beer
Beer was a staple of early modern diets across northern Europe and the Atlantic World. While its profound social, economic, and cultural significance is well established, little is known about the nature and quality of the drink itself, particularly its nutritional characteristics. Until now, attempts to estimate calorie and alcohol content have been monodisciplinary in approach, involving either theoretical calculations based on grain content, or a rough approximation with modern equivalents. Using sixteenth-century Ireland as a case-study, this article describes an interdisciplinary approach to the problem of early modern beer. Exploiting a rich seam of unpublished archival material, the project recreates an early modern beer, using the most appropriate ingredients, equipment, and processes possible. Scientific analysis of the finished drink offers new perspectives on beer as a dietary staple. The project is a model for integrating practical or experimental approaches into mainstream historical study, and the practice of radical interdisciplinarity. It represents the most comprehensive effort to recreate an historic beer in any context to date, bringing together historians, experimental archaeologists, agronomists, microbiologists, brewing scientists, craftworkers, farmers, and maltsters to tackle problematic questions about the past.
Synthetic textile materials are noted as one of the major contributors to microfiber release from household laundry. The higher usage of synthetic textiles was noted as one of the major reasons for the leaching of microfibers into the aquatic system. Though few laundry aids are available to control the release of microfiber from laundry, no successful methods were developed to control it in the fabric itself. Hence, this research aimed to analyze the effectiveness of surface modification of polyester fabric using lipase enzyme and its impact on microfiber shedding. Taguchi’s L9 orthogonal array was adopted to optimize the enzyme treatment process parameters to reduce microfiber shedding. The results showed that enzyme concentration was the major influencing factor with a contribution of 35.56%, followed by treatment pH (35.247%), treatment time (17.46%), and treatment temperature (11.74%). The optimization with S/N ratio showed minimum microfiber shedding at an enzyme concentration of 0.5 gram per liter (gpl), treatment temperature of 55°C, 6.5 pH, and a treatment time of 45 minutes. Knitted polyester fabric treated with the optimized enzyme treatment condition showed a significant reduction (p<0.05) in microfiber shedding (count—79.11% and mass—85.68%). The surface changes and the interaction of the enzyme on the fabric were confirmed by hydrolytic activity and FTIR analysis. The optimized treatment on different knit structures and fabric with different grams per square meter (GSM) indicated the versatility of the treatment irrespective of fabric parameters. The repeated laundry process (20 washing cycles) showed that the enzyme-treated samples had a significant level (p<0.05) of reduction in shedding than the control sample. The difference in shedding after 20 washes supports the efficiency and longevity of the enzyme treatment process in reducing microfiber shedding.
Beer is one of the oldest and most widely consumed alcoholic beverages. Haze formation in beer is a serious quality problem, as it largely shortens the shelf life and flavor of beer. This paper reviews the factors affecting haze formation and strategies for reducing haze. Haze formation is mainly associated with specific chemical components in malt barley grains, such as proteins. The main factor causing haze formation is a cross-linking of haze active (HA) proteins and HA polyphenols. Many HA proteins and their editing genes or loci have been identified by proteomics and quantitative trait locus (QTL) analysis, respectively. Although some technical approaches have been available for reducing haze formation in beer, including silica and polyvinylpolypyrrolidone (PVPP) adsorbent treatments, the cost of beer production will increase and some flavor will be lost due to reduced relevant polyphenols and proteins. Therefore, breeding the malt barley cultivar with lower HA protein and/or HA polyphenols is the most efficient approach for controlling haze formation. Owing to the completion of barley whole genome sequencing and the rapid development of modern molecular breeding technology, several candidate genes controlling haze formation have been identified, providing a new solution for reducing beer haze.
In large-sized breweries, rough beer clarification is still carried out using Kieselguhr filters notwithstanding their environmental and safety implications. The main aim of this work was to test an innovative rough beer clarification and stabilization process involving enzymatic treating with Brewers Clarex®, centrifuging, rough filtering across 1.4-μm ceramic hollow-fiber membrane at 30 °C, and fine filtering through 0.45-μm cartridge filter. When feeding an enzymatically-pretreated and centrifuged rough beer with permanent haze (HP) of 2 or 14 European Brewery Convention unit (EBC-U), its primary clarification under periodic CO2 backflushing yielded a permeate with turbidity of 1.0–1.5 EBC-U at a high permeation flux (2.173 ± 51 or 593 ± 100 L m⁻² h⁻¹), much greater than that typical of powder filters. The final beer was brilliant (HP = 0.57 ± 0.08 EBC-U) with almost the same colloidal stability of the industrial control and an overall log reduction value (~5.0 for the selected beer spoilage bacterium or 7.6 for the brewing yeast) in line with the microbial effectiveness of current sterilizing membranes. It was perceived as significantly different in flavor and body from the industrial control at a probability level of 10% by a triangle sensory test, as more likely related to the several lab-scale beer-racking steps used than to the novel process itself.
Turbidity in beer will continue to be a major topic as many origins of haze have already been discovered, but it is not always possible to identify its immediate cause. In addition to beer foam, one of the most important visual quality characteristics of filtered beers is gloss fineness. Consequently, in the case of an undesirable haze, it is first necessary to identify the haze particles and how to remove them. The topic is covered in two sections. This review labelled Part 1 and a second review labelled Part 2. Part 1 addresses turbidity in general, the causes and origins of turbidity and the different analytical methods for turbidity identification and removal. Part 2 focuses on Raman spectroscopy and provides a general overview of the physical basics, the areas of application, possible gaps and the challenge for its use for identifying turbidity in beer and beverages.
Enzymatic modification, using a protease from Bacillus licheniformis (Subtilisin A), was carried out on polyamide 6.6 (PA6.6) fabric to make it more amenable to water-based nanocoatings used to impart electrical conductivity. The modified PA6.6 fibers exhibit a smoother surface, increased hydrophilicity due to more carboxyl and amino groups, and larger ζ-potential relative to unmodified polyamide. With its improved hydrophilicity and surface functionality, the modified textile is better able to accept a water-based nanocoating, composed of multiwalled carbon nanotubes (MWCNT) stabilized by sodium deoxycholate (DOC) and poly(diallyldimethylammonium chloride) (PDDA), deposited via layer-by-layer assembly. Relative to unmodified fabric, the enzymatically modified fibers exhibit lower sheet resistance as a function of PDDA/MWCNT-DOC bilayers deposited. This relatively green technique could be used to impart a variety of useful functionalities to otherwise difficult-to-treat synthetic fibers like polyamide.
Enzymatic hydrolysis on synthetic fibers enhances the hydrophilicity and solves the concerns regarding the environmental issues of textile industry. Lipase hydrolyses ester linkages in polyethylene terephthalate and produces polar hydroxyl and carboxylic groups. The study aims to identify and investigate the effect of enzyme treatment on weight loss and surface modification of polyester fabrics. Also the functional groups present before and after treatment and the effect of enzyme treatment on the improvement of dye uptake are studied. The test indicates that enzymatic process creates less surface damage, weight loss and improved moisture regain, dye uptake, and shear properties.
Today’s beer differs in many ways from the original hazy brew made from grains and water left in the sun to ferment. The development of brewing procedures introduced filtration and colloidal stabilization as key elements in beer preservation and stability. Colloidal stability of beer is the most important factor in beer quality. Colloidal particles significantly shorten beer’s storage time, but most importantly, also influence its appearance. Colloidal stabilization involves one or more procedures that are applied at different stages during production and result in colloidal stability of the final product. Beer is considered to be colloidal stable if it can be stored for several months at 25 °C without exhibiting any changes in composition or other properties; specifically, beer has to be able to remain clear without any signs of precipitation. Since colloidal stability is of primary importance for the consumer, retail requirements have resulted in many solutions for this issue. Stabilization agents have to be reliable during the filtration and stabilization processes. Additionally, renewable agents are highly desirable. The level of colloidal stability required depends on the desired storage time and temperature after the beer has been packed. Consumers have higher and higher expectations that the industry has to follow.
Atualmente vem se observando o intenso interesse em alimentos que, além da nutrição, ofereçam atividades funcionais em relação à prevenção de alguns distúrbios fisiológicos. A presença dos compostos fenólicos em alguns alimentos faz com que os mesmos sejam capazes de prevenir doenças como câncer, arteriosclerose, doenças cardíacas, inflamações, entre outros benefícios, pelo fato de os mesmos agirem como agentes antioxidantes no organismo. Sendo a cerveja umas das bebidas mais consumidas pelos brasileiros, e por apresentar em sua composição compostos do tipo fenólicos, este estudo objetivou realizar uma análise qualitativa e comparativa da composição destes em cinco diferentes marcas de cervejas do tipo Pilsen mais consumidas pela população brasileira, relacionando-os com seus efeitos à saúde humana. Foram utilizados os métodos de Reações Cromogênicas – RCR e Cromatografia em Camada Delgada – CCDA para identificação dos compostos, métodos que se mostraram eficientes perante a proposta do trabalho. Encontraram-se nas cervejas a presença de compostos do grupo dos flavonóides, catequinas e taninos, além da presença de ácidos fenólicos, como o cafeico, vanílico e ferúlico. Tais substâncias fazem com que a cerveja adquira um potencial antioxidante que apresenta benefícios à saúde de quem a consome, indiferentemente da marca, já que todas apresentaram semelhante padrão de compostos do tipo fenólicos, podendo assim desprover principalmente de ação antiarterioscleróticas, anti-inflamatórias, anticarcinogênicas, antitrombóticas, entre outras.
Fourier transform infrared spectroscopy (FTIR) is one of the most important instrumental techniques used to study the molecular structure of organic polymers. As part of our efforts to increase instrumental use in the undergraduate chemistry laboratory we have developed a quantitative FTIR experiment for use in our quantitative and instrumental analysis courses. The objective of the experiment is to determine the percent composition of PVAc in copolymers and blends with polyethylene (PE) and n-vinyl pyrrolidone (PVP). We report on the experimental methods used and the results obtained on examining the quantitative FTIR and elemental analysis of a series of ethylene-vinyl acetate (EVAc) copolymers. The EVAc copolymers ranged from 10% to 70% PVAc. Copolymers and blends of n-vinyl pyrrolidone-polyvinyl acetate (PVP/PVAc) ranging from 20% to 80% PVAc were also analyzed.
Lipase from Burkholderia cepacia was immobilized in a silica matrix and dried in high pressure carbon dioxide media (aerogel). The protic ionic liquid (PIL) was used in the immobilization process by encapsulation. The objective of this work was to evaluate the influence of the drying technique using supercritical carbon dioxide in biocatalysts obtained through the sol-gel technique by evaluating temperature and pressure and, after selecting the best drying conditions, to investigate the application of the technique for the biocatalyst using ionic liquid as an additive in the immobilization process. The results for immobilized biocatalysts showed that the best conditions of pressure and temperature were 100 bar and 25 degrees C, respectively, giving a total activity recovery yield of 37.27% without PIL (EN) and 44.23% with PIL (ENLI). The operational stability of the biocatalysts showed a half-life of 11.4 h for ENLI and 6 h for EN. Therefore, solvent extraction using supercritical CO2, besides shortening drying time, offers little resistance to the immobilization of lipases, since their macropores provide ample room for their molecules. The use of the ionic liquid as an additive in the process studied for the immobilization of enzymes produced attractive yields for immobilization and therefore has potential for industrial applications in the hydrolysis of vegetable oils.
Dipeptide syntheses starting from Ac-L-Tyr-OEt or Z-L-X-OMe (X: Asp, Tyr, Phe, Arg, Lys or Thr) and glycine amide in biphasic reaction media were achieved using two commercially available porcine pancreatic lipase (PPL) preparations (crude (cPPL) and purified PPL (pPPL)). Under the mild conditions employed, α-chymotrypsin, a pancreatic protease that also presents esterase activity, catalyzed Ac-L-Tyr-Gly-NH2 synthesis with high productivity. Product hydrolysis also occurred in most of the syntheses studied. Polyacrylamide gel electrophoresis, enzymatic assays employing specific chromogenic substrates and size-exclusion chromatography revealed that cPPL and pPPL contain contaminant proteases and, therefore, exhibit esterase and amidase activities. Overall, these data indicate that those contaminants may be the main catalysts of peptide bond synthesis when Nα-blocked-L-amino acid esters and the commercial PPL preparations are used. On the other hand, such data do not contest the possibility of using such enzyme preparations as an inexpensive source of catalysts for dipeptide synthesis under soft conditions.
Cellulose whiskers resulting from HCl acid hydrolysis of tunicin were subjected to TEMPO-mediated oxidation under various conditions and the extent of the resulting oxidation was characterized by Fourier-transform infrared spectroscopy (FT-IR), conductimetry, X-Ray diffraction analysis and transmission electron microscopy (TEM). With degree of oxidation of up to 0.1 the samples kept their initial morphological integrity and native crystallinity, but at their surface the hydroxymethyl groups were selectively converted to carboxylic groups, thus imparting a negative surface charge to the whiskers. When dispersed in water these oxidized whiskers did not flocculate and their suspensions appeared birefringent when viewed between cross polarizers, thus indicating a liquid crystalline behavior.
Spectrophotometric determination of total protein is used in several areas such as clinical analysis, food science and technology, biochemistry, protein chemistry, physiology. Five spectrophotometric methods are mostly used: biuret, Lowry, Bradford, Smith and UV absorption. In this review a general overview of these methods is presented (interferences, applications); other methodologies are also discussed.
Discharging methylene blue (MB) dye into waste streams has caused severe environmental problems to the aquatic life ecosystem and hence to human beings. Hence, this work investigated the feasibility to use polypropylene (PP) film waste to prepare carboxyl/nitro-functionalized PP microparticles (COOH/NO2-PP) for the adsorption of MB from aqueous solutions. PP powder was prepared by dissolution/precipitation method from PP film waste, followed by treatment with nitric acid at 130 °C. ATR-FTIR analysis proved the structure of PP and the existence of carboxyl and nitro groups on the surface. The enhancement in surface hydrophilicity of PP after treatment was confirmed by contact angle measurements. The effects of polymer dosage, pH, and contact time on the adsorption process were studied. The results showed that the removal of MB from water increased with increasing these parameters. The kinetic and equilibrium studies showed that the Langmuir isotherm and pseudo-second-order kinetic model fitted the experimental data well. This suggested that the adsorption process was chemisorption. A maximum adsorption capacity of 14.33 mg MB/g-polymer was achieved at 23 °C and neutral pH (6.5). The free energy change had a negative value, which signifies the spontaneity of the adsorption process. Thereby, waste PP can be converted into useful adsorbents for treating cationic dye-polluted water.Graphic abstract
This study is to optimize the enzymatic processing conditions of Polylactic Acid (PLA) fiber using lipase from Porcine pancreas as an environmental technology. Hydrolytic activity dependent on pH, temperature, enzyme concentration, and treatment time, and structural change of PLA fiber were evaluated. The PLA fiber hydrolysis by lipase was maximized at 50% (o.w.f) lipase concentration 50^{\circ}C for 120 minutes under pH 8.5. There was a change of the protein absorbance in the treatment solution before and after the lipase treatment. In addition, there was no substantial change in the molecular and crystalline structures of PLA by lipase treatment as confirmed by DSC, XRD, and FT-IR.
Beer contains approximately 500 mg/L protein depending on the brewing procedures employed. This protein is in the form of polypeptides, the majority of which lie within the 10-40 kD size range. Some of these polypeptides are responsible for causing colloidal haze, others enhance foam stability and the remainder appear to have no function in beer except to contribute to mouth-feel. The polypeptides responsible for haze formation are those that can combine with polyphenols to produce a visible cloudy haze. This is undesirable as it can have a negative effect on the beer's shelf life. One way to reduce this effect is to remove these polypeptides using silica gels. It is important that this removal is selective, and the desirable foam enhancing polypeptides are not removed. Data will be presented to show that beer polypeptides are glycosylated and that silica preferentially adsorbs glycoproteins, particularly those with protein components rich in the amino acid proline. The molecular size and composition of glycoproteins recovered from untreated beer, cooked adjunct, silica exposed to beer and beer aged for one year are presented. Glycoproteins involved in foam, and the apparently functionless polypeptides, will be discussed in a subsequent paper.
The fluorescence spectra and lifetimes of diluted beer have been explored and found not to report on protein removal either by silica or tannic acid, nor polyphenol uptake by PVPP. Comparing the fluorescence spectra of beer with that of tea and hops, it seems that proteins, complex polyphenols and iso-α-acids can contribute to the intrinsic fluorescence of beer, although the contribution from polyphenols must be minimal since treatment with PVPP does not dramatically change the background fluorescence. To eliminate the problem of background fluorescence haze-active protein was isolated. Steady-state and time-resolved fluorescence techniques were used to characterise these and to monitor their uptake by different silica gels as a function of pH. Heat treated large pore volume, small surface area silicas were the more effective adsorbers for the proteins under study, with pH 4 being optimum. Using both intrinsic amino acid fluorescence and the extrinsic fluorophore fluorescamine, the time-resolved fluorescence anisotropy has been measured and the radius of the isolated haze protein found to be ∼ 35 Å. Comparisons have been made with proteins of known size and structure such as human and bovine serum albumins (HSA and BSA).
J. Inst. Brew. 116(4), 360–368, 2010 Beer is a complex mixture of over 450 constituents. In addition, it contains macromolecules such as proteins, nucleic acids, poly-saccharides and lipids. Proteins influence the entire brewing process with regard to enzymes, which degrade starch, β-glucans and proteins; with protein-protein linkages that stabilize foam and are responsible for mouthfeel and flavour stability; and in combination with polyphenols, thought to form haze. With this complexity, problems in processability are as various as the con-stituents. Several substances in beer are responsible for haze formation. Organic components such as proteins, polyphenols and carbohydrates (α-glucans, β-glucans) are known to form haze. In addition, inorganic particles such as filter aids and label remains can cause increased turbidity. In this article only non-microbiological induced hazes are described. Many studies have been conducted on the identification of haze and foam active components in beer. Hence the aim of this work was to survey the different possibilities of haze formation and for haze identifi-cation. A summary is provided on methods for haze identifica-tion including dyeing methods, microscopic analyses and size exclusion chromatography.