Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties

BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin‐like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene‐related peptide (CGRP)‐like peptides demonstrated an increase in CGRP‐like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin‐converting enzyme (ACE)‐1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut‐off adapted to the peptide composition, may provide an effective means to concentrate CGRP‐like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut‐off of the membrane only, as is currently done in the literature. Copyright © 2010 Society of Chemical Industry     

Binding of ²³⁹Pu and ⁹⁰Sr to organic colloids in soil solutions: evidence from a field experiment

Colloidal transport has been shown to enhance the migration of plutonium in groundwater downstream from contaminated sites, but little is known about the adsorption of ??Sr and plutonium onto colloids in the soil solution of natural soils. We sampled soil solutions using suction cups, and separated colloids using ultrafiltration to determine the distribution of 23?Pu and ??Sr between the truly dissolved fraction and the colloidal fraction of the solutions of three Alpine soils contaminated only by global fallout from the nuclear weapon tests. Plutonium was essentially found in the colloidal fraction (>80%) and probably associated with organic matter. A significant amount of colloidal ??Sr was detected in organic-rich soil solutions. Our results suggest that binding to organic colloids in the soil solutions plays a key role with respect to the mobility of plutonium in natural alpine soils and, to a lesser extent, to the mobility of ??Sr.     

Chemical composition,nutritive value and voluntary intake of tropical tree foliage and cocoyam in pigs

The composition of the leaves of cocoyam (Xanthosoma sagittifolium) and of two trees (Trichanthera gigantea and mulberry, Morus alba), their nutritive value in pigs and voluntary intake by pigs were determined. The average protein content ranged from 170 to 240 g kg^?1 dry matter (DM) and that of neutral detergent fibres from 218 to 398 g kg^?1 DM. The leaves are interesting sources of calcium (up to 69 g kg^?1 DM), potassium, iron and manganese. The proteins are well balanced in essential amino acids, with lysine ranging from 43 to 57 g kg^?1 proteins. The apparent faecal digestibility was determined by difference in 35 kg pigs fed a diet containing 35% leaf meal. The digestibility coefficients of DM, N and energy were, respectively, 47–57, 33–36 and 51–53%. The digestible energy value ranged from 1.674 to 2.037 kcal kg^?1 DM. The voluntary intake of Trichanthera and Xanthosoma was measured in sows weighing 100 kg on average. The intake reached 3.4 kg fresh leaves day^?1 (0.51 kg DM) and 1.0–1.1 kg dry leaf meal/day. It is concluded that low energy density is the main limiting factor of tree foliage for pig nutrition but that they are good sources of minerals and well‐balanced proteins. Copyright © 2005 Society of Chemical Industry     

Forecast of mycotoxins levels in soft wheat, durum wheat and maize before harvesting with Qualim��tre?

Some mycotoxins are produced by several Fusarium species during cultivation and are found in wheat and maize grain. Since 2000, Syngenta has organised a large field survey. Agronomic and climatic data and grain samples have been collected for mycotoxin analysis in France and Belgium. The importance of the agroclimatic factors and their interactions on the mycotoxin levels in grain has been estimated. The climate around flowering stage is the major factor for deoxynivalenol (DON) in wheat. The main agronomic criteria are residue management and the variety sensitivity to this mycotoxin. For DON, zearalenone and fumonisins in maize, the climate from flowering stage until harvest is the major factor. Then, according to each mycotoxin, the main agronomic criteria are the harvest condition (date and grain moisture), the corn borer infestation and the variety sensitivity to these mycotoxins. Over the years, the database has been used to define models to predict the mycotoxin risk before harvesting. Grain purchasers enter the required agronomic data via the Syngenta Internet site and define their grain purchasing areas. They also define the flowering period for wheat and corn borer infestation for maize. After calculation which integrates climatic data, the purchasers receive reports with forecasts of mycotoxin levels. Prediction is based on different agro-climatic statistical models specifically configured according to the different regions of production in France and Belgium. This approach is called Qualimètre^? and was the first service in France and Belgium to forecast the grain mycotoxin level for wheat in 2004 and maize in 2006.     

Effect of vanillin, ethyl vanillin, and vanillic acid on the growth and heat resistance of Cronobacter species

Preservatives could be part of an effective intervention strategy for the control of Cronobacter species in foods, but few compounds with the desired antimicrobial properties have been identified to date. We examined the antibacterial activity of vanillin, ethyl vanillin, and vanillic acid against seven Cronobacter spp. in quarter-strength tryptic soy broth with 5 g/liter yeast extract (TSBYE) adjusted to pH 5.0, 6.0, and 7.0 at 10, 21, and 37°C. All compounds exhibited pH- and temperature-dependant bacteriostatic and bactericidal activity. MICs of vanillin and ethyl vanillin consistently increased with decreasing pH and temperature, but vanillic acid had little activity at pH values of 6.0 and 7.0. The MICs for all temperatures, pH values, and bacterial strains tested were 2 mg/ml ethyl vanillin, 3 mg/ml vanillin, and >8 mg/ml vanillic acid. MBCs also were influenced by pH, although significantly higher concentrations were needed to inactivate the bacteria at 21°C than at 10 or 37°C. Survivor curves for Cronobacter sakazakii strains at the MBCs of each compound revealed that all treatments resulted in immediate loss of cell viability at 37°C. Measurements of propidium iodide uptake indicated that the cell membranes were damaged by exposure to all three compounds. The thermal resistance of C. sakazakii was examined at 58°C in TSBYE supplemented with MBCs of each compound at pH 5.0 and 6.0. D-values at pH 5.0 were reduced from 14.56 ± 0.60 min to 0.93 ± 0.01, 0.63 ± 0.01, and 0.98 ± 0.02 min for vanillin, ethyl vanillin, and vanillic acid, respectively. These results suggest that vanillin, ethyl vanillin, and vanillic acid may be useful for the control of Cronobacter spp. in food during preparation and storage.     

Properties of laboratory made yellow poplar (Liriodendron tulipifera) laminated veneer lumber: effect of the adhesives

Four different commercial resin formulations namely cross-linked polyvinyl acetate (XPVAc), melamine urea formaldehyde (MUF), urea formaldehyde (UF) and melamine formaldehyde (MF) were used to produce laminated veneer lumber (LVL) from yellow poplar veneers in the laboratory. Physical and mechanical properties were evaluated using ASTM (D 1037, D 906, D 5456) standards and compared. Internal bond, tensile shear and block shear strengths of specimens subjected to accelerated (boiled water) and cyclic (repeated cold water) conditions were also determined. Strength properties of yellow poplar LVL were improved compared with the solid wood. The properties of XPVAc bonded LVL were superior or comparable to the thermosetting adhesives. This study clearly indicated that cross-linked PVAc can be used to manufacture LVL with acceptable properties.     

Development of a questionnaire to assay recalled liking for salt,sweet and fat

Liking for a sweet, salty or fatty diet may induce overconsumption of simple carbohydrates, sodium or lipids. Measuring overall liking of the corresponding sensory sensations contributes to understanding the determinants of dietary behaviours. However, no standardized validated questionnaire assaying these sensations is currently available. In the present study, we developed a web-based questionnaire, “PrefQuest”, which measures recalled liking for the following four sensations: salt, fat and salt, sweet, fat and sweet. PrefQuest included four types of items: (1) liking for sweet, fatty-sweet and fatty-salty foods, (2) preferences in the level of seasoning by adding salt, sweeteners, or fat, (3) preferences for types of dishes in a restaurant menu and (4) overall questions about sweet-, salt- and fat-related behaviours. A development study (n = 198) demonstrated that PrefQuest was feasible, well-perceived, only lasted about 20 min and that items were repeatable (overall mean intra-class correlation coefficient: 0.77, SD 0.08). Construct validity was then evaluated on a larger population sample (n = 47 803). The underlying structure within each of the four sensations was determined by exploratory factor analysis and then internally validated by confirmatory factor analysis. After a selection of the most relevant items, the salt, fat-and-salt, sweet, and fat-and-sweet scales exhibited a theoretically meaningful factor structure, unidimensional for the salt scale and with interrelated sub-dimensions for the sweet, fat-and-salt, and fat-and-sweet scales. Based on the fat-and-sweet and fat-and-salt scales, a fat model was also unveiled. For each factor, internal consistency as well as convergent and divergent validities were demonstrated. Overall, PrefQuest is an internally valid and original tool that can be used to assay recalled liking for sweet, salt, and fat considered altogether or separately as fat and salt or fat and sweet, and can be applied to large population surveys.     

Large-scale production of a hypoallergenic preparation of F(ab′)2 fragments from bovine colostrum

A method for the production of bovine colostral F(ab′)₂ fragments at pilot-plant scale was developed. Optimum yield of immunoglobulins in colostral whey was obtained after rennet treatment of first milking colostrum. Pepsin digestion was carried out directly on the colostral whey at pH 3·8 for 4 h, which led to the complete digestion of immunoglobulins into F(ab′)₂ fragments. Elimination of β-lactoglobulin, the main immunogenic protein, was achieved by anion exchange on Duolite A560 at pH 6·0. The preparation was diafiltered with a 5000 Da membrane and the retentate spray-dried. The powder obtained contained approximately 34% F(ab′)₂ fragments, with an antibody activity three times higher than the initial colostrum.     

Influence of Ignition Sources on Heat Release Rate in the Furniture Calorimeter

When measuring the production rates of heat and smoke of upholstered furniture the ignition source must not influence the test results. In this paper variations in the strength, application time and geometry of the ignition burner used in the furniture calorimeter are studied. Results from replicate furniture calorimeter chair test show that the burning behaviour is almost independent of the burner intensity in the applied regime. Tests on six different furniture items were performed in the furniture calorimeter. The test objects were exposed to three intensity levels of ignition source. The sources were: a large propane burner giving 30 kW during 120 s and a smaller propane burner used at two levels of heat output, 1.7 and 5.8 kW during 90 s. The results showed that the burning behaviour of the furniture was very similar regardless of which burner was used. This was especially evident when the time regime between 50 and 400 kW was studied. The length of this period is a measurement on how quick untenable conditions are developing in a single, well-ventilated compartment.