A Novel Process for the Recovery of Polyphenols from Grape (Vitis vinifera L.) Pomace

ABSTRACT: A novel process for enzyme-assisted extraction of polyphenols from winery by-products was established on a pilot-plant scale. Optimization of enzymatic hydrolysis of grape skins, that is, selection of pectinolytic and cellulolytic enzymes, enzyme-substrate ratio, and time-temperature regime of enzymatic treatment, was conducted on a laboratory scale. Enzyme activities were monitored by viscosity measurement of resuspended grape pomace and by quantification of oligomeric pectin and cellulose degradation products released from cell wall material. Optimal conditions were obtained with 5000 ppm (based on dry matter) of a pectinolytic and 2500 ppm of a cellulolytic enzyme preparation, respectively, at 50°C, which were also applied in pilot-plant scale experiments. Concomitant determination of individual polyphenolics demonstrated a significantly improved yield for most compounds when compared with experiments without enzyme addition. Recovery rates were comparable to those obtained when grape pomace was extracted using sulfite. Pre-extraction of the pomace with hot water followed by treatment with cell wall degrading enzymes even increased yields of phenolic compounds. Only some quercetin glycosides and malvidin coumaroylglucoside were partly hydrolyzed due to enzyme side activities. This new process may provide a valuable alternative to the application of sulfite, which is considered crucial in food processing.     

Evaluation of the adsorption behavior of flavonoids and phenolic acids onto a food-grade resin using a D-optimal design

A D-optimal experimental design has been applied to study the single-compound adsorption of caffeic acid, catechin, chlorogenic acid, and phloridzin from aqueous solutions onto a food-grade styrene–divinylbenzene copolymer. Among the parameters determining adsorption the solute concentration, the temperature, the pH value, and the resin amounts were evaluated. Mathematical models were established for each phenolic compound allowing to predict the adsorption behavior under any given condition. Furthermore, determination of the optimal adsorption conditions using the mathematical equations was possible, thus facilitating systematic optimization of the adsorption process. The Langmuir and Freundlich isotherms have been applied to describe the adsorption of the four phenolic compounds and were used to interpret the adsorption behavior. Finally, ΔG, ΔH and ΔS were determined to evaluate polyphenol adsorption based on thermodynamic parameters. The present study contributes to optimize adsorber technology, thus, being a prerequisite for establishing cost-efficient technological processes for the recovery of plant phenolic compounds.     

Spiroplasma lineolae sp. nov., from the horsefly Tabanus lineola (Diptera: Tabanidae)

Spiroplasma strain TALS-2T from the viscera of the striped horsefly, Tabanus lineola, collected in Georgia was serologically distinct from other Spiroplasma species, groups, putative groups, and subgroups. Light and electron microscopy of cells of strain TALS-2T revealed helical motile cells surrounded only by a single cytoplasmic membrane. The organism grew in M1D and SP-4 liquid media. Growth also occurred in 1% serum fraction medium and in conventional horse serum medium. Growth in liquid media was serum dependent. The strain passed through 220-nm filter pores, but was retained in filters with 100-nm pores. The optimum temperature for growth was 30 degrees C. Multiplication occurred at temperatures from 20 to 37 degrees C, with a doubling time at the optimum temperature of 5.6 h in M1D broth. Strain TALS-2T catabolized glucose but hydrolyzed neither arginine nor urea. The guanine-plus-cytosine content of the DNA was 25 +/- 1 mol%. The genome size was 1,390 kbp. Six isolates serologically similar to strain TALS-2T were obtained from the same host in coastal Georgia. Three strains closely related to strain TALS-2T were isolated from the horsefly Poeciloderas quadripunctatus in Costa Rica. Strain TALS-2T (= ATCC 51749), a representative of group XXVII, is designated the type strain of a new species, Spiroplasma lineolae (Mollicutes: Entomoplasmatales).     

Process and storage stability of anthocyanins and non-anthocyanin phenolics in pectin and gelatin gels enriched with grape pomace extracts

Gelatin and pectin gels were supplemented with anthocyanin extracts obtained from grape pomace and stored either under neon light (20 ± 2 °C) or in the dark (20 ± 2 and 6 ± 2 °C, respectively) for a period of up to 24 weeks. During storage, antioxidant activities of the samples (FRAP and TEAC assays), total phenolic contents (Folin–Ciocalteu assay) and the amounts of monomeric and polymeric anthocyanins and of non-anthocyanin phenolics were monitored spectrophotometrically and by HPLC, respectively. Processing of the gels had the most significant effect on the total phenolic contents in all samples, resulting in total losses up to 24.6%. Light considerably decreased the phenolic compounds during storage, whereas the effect of temperature on their stability was less pronounced. Total phenolic contents of illuminated samples decreased from 243.6 to 82.6 mg/kg in the gelatin gels within 24 weeks of storage and from 279.8 to 139.5 mg/kg (pectin gel, 16 weeks of storage). In contrast, antioxidant activity of the samples was only slightly reduced or remained virtually unchanged. Thus, the model gels still exhibited brilliant colors and strong antioxidant capacity even after storage of 24 weeks at ambient temperature.     

Prevalence of virulence genes in Escherichia coli isolated from food in Casablanca (Morocco)

This study was undertaken to determine the frequency of potentially pathogenic Escherichia coli (E. coli) strains among E. coli isolated from Casablanca, Morocco. The E. coli strains were isolated from ground beef (n = 140), turkey (n = 200), sausage (n = 120), seafood (n = 60), domestic water (n = 35) and well water (n = 50). The prevalence of E. coli was 48%, 45%, 35.5%, 30%, 8.3%, 0%, for well water, ground beef, turkey, sausage, sea food and domestic water, respectively. Two hundreds E. coli isolates were tested for the presence of 17 virulence genes associated with strains causing intestinal and extra-intestinal infections. The virulence genes included stx1, stx2, lt, st, hlyA, aggA, saa, astA, iucD, cnf1, eaeA, bfpA, ial, ipaH, afa, pap and sfa. PCR showed that 37% (74) of E. coli isolates carried one or more of these virulence genes. No virulence genes were found in E. coli strains isolated from sea food samples. In contrast, 10% of the ground beef samples, 18% of the turkey samples, 17.5% of sausage samples and 6% of well water contained specific factors for intestinal E. coli pathogens.     

Investigations on the conversion of onion aroma precursors S‐alk(en)yl‐L‐cysteine sulphoxides in onion juice production

Onion flavour develops when the cells are disrupted, allowing the enzyme alliinase (EC 4.4.1.4) to act upon the aroma precursors S‐alk(en)yl‐L ‐cysteine sulphoxides (ACSOs). For maximum flavour release, optimal cell disintegration and complete enzymatic conversion of ACSOs are desired. To assess an industrial scale onion juice extraction in regard to the extent of cell disintegration and the rate of enzymatic ACSO conversion, samples from all mass flows (ie onion, macerate, juice and pomace) were subjected to ACSO analysis. Applying a modified HPLC method, which allows baseline separation of the aroma precursors, three ACSOs, namely methyl‐, propyl‐ and 1‐propenyl‐L ‐cysteine sulphoxides (MCSO, PCSO and 1‐PeCSO), were determined. Initial ACSO ratios changed in the course of increasing degree of comminution from 17:83 to 100:0 (MCSO/1‐PeCSO). Only negligible amounts of PCSO were detected (<9.2 nmol g^?1 fresh weight (fw)), contributing less than 0.2% to the total ACSO content. For evaluation of the disintegration efficiency a chart was established consisting of an abscissa representing a percentage scale of ruptured cells and ordinates for the development of the marker parameters ACSOs and reaction product pyruvate relative to their initial contents. From this correlation a cell disintegration percentage after grinding of about 70% was deduced according to the determined ACSO contents. On a molar basis, macerate, juice and pomace showed 15, 0.6–2.4 and 0.7–1.0% of initial ACSO contents respectively. Only trace amounts of 1‐PeCSO were found in the juice (<16 nmol g^?1 fw). MCSO was converted to almost 90%, indicating that enzymatic transformation, in a practical sense, goes to completion. Copyright © 2004 Society of Chemical Industry     

Recognition of Mycoplasma canis as part of the mycoplasmal flora of the bovine respiratory tract

Mycoplasma strain C3b was isolated in the Netherlands from the lung of a pneumonic calf. Forty similar strains were isolated afterwards from calves in 19 other herds in different parts of the Netherlands. Eight strains from eight different herds were investigated in this study. Results of tests to determine whether the organism catabolized glucose were inconclusive. Four strains, including strain C3b, apparently catabolized glucose under some test conditions; the remaining four strains did not. Although strain C3b and similar strains were slightly different from canine M. canis strains in growth inhibition tests and glucose metabolism tests, we concluded that strain C3b and similar strains have to be classified as M. canis. A close contact between calves and dogs was observed in several herds where strain C3b or similar strains were isolated. This is the first report of M. canis isolated from cattle.     

Engaging college science students and changing academic achievement with technology: A quasi-experimental preliminary investigation

Can modern, computer-based technology engage college students and improve their academic achievement in college? Although numerous examples detail technology’s classroom uses, few studies empirically examine whether technologically oriented pedagogical changes factually lead to positive outcomes among college students. In this pilot study, we used a quasi-experimental design to examine whether a technology enhanced research methods classroom led to increased student engagement and academic achievement among college students. Two features generally characterized the technology enhanced classroom experience: specific feedback generated from recordings of small group discussions and podcasts of class recordings. Technology enhanced classroom students demonstrated statistically significant increases in student engagement and improved academic achievement. These findings support previous efforts to use technology to enhance engagement and achievement among college students and they encourage future efforts.     

Quality of Shredded, Packaged Carrots as Affected by Different Washing Treatments

ABSTRACT: Different washing treatments with chlorinated and ozonated water were applied to carrots ( Daucus carota L.) on an industrial scale to improve the sensorial and microbial quality of packaged ready-to-eat produce. Quality of shredded carrots was determined by sensory evaluation and microbiological analysis. Washing shredded carrots resulted in increased sugar leaching and loss of sensorial quality, whereas prewashing uncut carrots with chlorine ensured sugar retention, reduced microbial load, and concurrently minimized cross-contamination. Comparable germ reduction was not achieved by prewashing with ozone. These findings demonstrated that prewashing uncut carrots with chlorine provided sufficient microbiological safety paired with improved sensorial properties.     

Data collection in future mobile networks

Future mobile networks will be increasingly heterogeneous. Already today, wireless LAN is used by many mobile network operators as an addition to traditional technologies like GSM and UMTS; WiMax and 3GPP Long Term Evolution (LTE) will be added. Having heterogeneous wireless networks, one challenging research question needs to be answered: Which user should be served by which access network and when to conduct a handover? For such decisions, information on the state of networks and terminals is required. In this publication, we simulate mobile networks in which a central entity called Network Resource Management (N-RM) gives handover recommendations to mobile terminals. Based on these recommendations and local knowledge on link qualities, the terminals choose the cell to switch to. The N-RM should have a global view on the networks to give best recommendations. We designed the Generic Metering Infrastructure (GMI), a publish/subscribe system to collect information about access networks and terminals efficiently. We investigate the tradeoff between the signalling overhead caused by data collection and the quality of the handover decisions and show, how smart monitoring can reduce the amount of measurement data while ensuring the efficient use of heterogeneous networks. In addition, our simulation results show that combined local and central handover decisions significantly increase the capacity of the networks as compared to only local decisions.