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     

Textural and ultrastructural changes during processing and storage of lightly preserved salmon (Salmo salar) products

The effect of a controlled lactic fermentation on textural and ultrastructural properties of salmon fillets was evaluated. When compared with a non‐inoculated cured sample, fermented salmon had unique textural properties since it exhibited significantly higher force (p < 0.05) and work (p < 0.001) values in a penetration test on two sampling days but a consistently lower hardness (p < 0.05) in a Texture Profile Analysis (TPA) rheological test. Study of the myofibrillar ultrastructure showed that basic structures were drastically damaged during processing and storage of fermented and cured salmon. Nevertheless, Z‐lines were better preserved in fermented samples. It is suggested that the slight protective effect of lactic fermentation with the starter L sake may be the consequence of a lower pH, by putatively inhibiting neutral or alkaline proteolytic enzymes. © 2000 Society of Chemical Industry     

Production of short-chain fatty acids from resistant starch in a pig model

This study was performed to estimate the pool of SCFA produced in the digestive tract of growing pigs after the consumption of diets containing dif-ferent sources of resistant starch (RS) (15 g per meal) (potato starch (PoS), high amylose maize starch (HS) and retrograded extruded HS (RHS)). SCFA production in vitro was respectively 19, 23 and 21 mmol g⁻¹ of fermented PoS, HS and RHS. The highest butyric acid production was observed with PoS. Fifty six, 36 and 19% respectively of ingested PoS, HS and RHS escaped digestion in the small intestine, whereas residual starch was completely fermented in the large bowel. Luminal total SCFA in the caeco-colon 7 h after the experimental meal were respectively 33, 78 and 105 mmol for PoS, HS and RHS, with PoS providing the highest production of butyric acid. Theoretical in vivo SCFA production, calculated on the basis of results for in vitro fermentation and ileal digestibility, differed from in vivo results for PoS (+65%) and HS (-13%), but not for RHS. This study reveals different rates of disappearance of RS both in vitro and in vivo. © 1998 SCI.     

Modulation of Starch Digestibility in Breakfast Cereals Consumed by Subjects with Metabolic Risk: Impact on Markers of Oxidative Stress and Inflammation during Fasting and the Postprandial Period

Scope : Decreasing postprandial glycaemic excursions may have a beneficial effect on inflammatory and oxidative stress profiles. In this study, we investigated the impact of carbohydrate digestibility modulation per se, as a means of reducing the glycaemic response, on metabolic and inflammatory responses in subjects with metabolic risk factors. Methods and results : Twenty healthy subjects with metabolic risk consumed a cereal product either high in Slowly Digestible Starch (HSDS) or low in SDS (LSDS) at breakfast daily for 3 weeks, in a cross‐over design. Following each 3‐week session, postprandial glycaemia, insulinaemia, the lipid profile, inflammation and oxidative stress markers were assessed and compared to those induced by ingestion of a glucose solution (as a reference). The 2‐h glycaemic and insulinaemic responses were significantly lower following the HSDS breakfast compared with the LSDS breakfast or glucose. No significant differences between the products were observed in terms of the lipid profile, C‐reactive protein, IL‐6 and tumour necrosis factor alpha. We observed a slight increase in fasting lipid peroxidation markers, including an increase in plasma malondialdehyde (MDA) and a decrease in whole blood glutathione (GSH), without significant alteration of urinary F2‐isoprostanes or plasma glutathione peroxidase (GPx) activity. Conclusion : Consumption of HSDS products for 3 weeks significantly altered both postprandial glycaemia and insulinaemia, but was not sufficient to modify the inflammatory profile. Consumption of both cereal products was associated with a slightly higher fasting oxidative stress profile.     

Environmentally Sustainable Construction: Knowledge and Learning in London Planning Departments

Environmentally sustainable construction is now recognised as a significant element of the broader sustainable development agenda and planners are being called upon to play a role in delivering more sustainable patterns of construction and development. This puts particular demands on the knowledge resources of planners since knowledge is implicated in the power relations between planners and developers. This paper examines the interrelationship between knowledge of environmentally sustainable construction and practice in planning departments. Drawing on a survey of and interviews with planners in London, it discusses the construction of knowledge within the dynamics of planning organisations and the potential for learning to promote a more sustainable built environment. Wenger's concept of communities of practice frames the analysis, alongside consideration of the translation of knowledge into bureaucratic and usable forms and the role of knowledge brokers in this process.     

Lysine‐241 Has a Role in Coupling 2OG Turnover with Substrate Oxidation During KDM4‐Catalysed Histone Demethylation

The JmjC histone lysyl demethylases (KDMs) play important roles in modulating histone methylation states and have the potential to be regulated by oxygen availability. Lys241 of the KDM4 subfamily is proposed to be important in oxygen binding by KDM4A. We report evidence that, although Lys241 is unlikely to be directly involved in oxygen binding, it has an important role in coupling 2‐oxoglutarate cosubstrate oxidation with lysine demethylase activity. The results suggest that compounds promoting the uncoupling of substrate oxidation are of interest as JmjC‐KDM inhibitors.     

Structure-Activity Relationship and Crystallographic Studies on 4-Hydroxypyrimidine HIF Prolyl Hydroxylase Domain Inhibitors

The 2-oxoglutarate-dependent hypoxia inducible factor prolyl hydroxylases (PHDs) are targets for treatment of a variety of diseases including anaemia. One PHD inhibitor is approved for use for the treatment of renal anaemia and others are in late stage clinical trials. The number of reported templates for PHD inhibition is limited. We report structure–activity relationship and crystallographic studies on a promising class of 4-hydroxypyrimidine-containing PHD inhibitors.     

Vertically aligned carbon nanotube‐based composite: Elaboration and monitoring of the nanotubes alignment

We present the different elaboration steps of a composite formed of carbon nanotubes (CNT) carpet embedded in an epoxy polymer. Detailed characterization at each step of the elaboration process is performed. The good alignment of CNT in as‐grown carpets is kept all along the elaboration process of the composite, as it is measured at both macro and microscopic scales by X‐ray scattering. We also ensured by X‐ray fluorescence measurements that the iron‐based catalyst particles used for the synthesis were removed from the carpet after a high temperature post‐annealing treatment. These measurements give valuable information for further applications involving unidirectional nanotube composites and membranes, where CNT alignment is a key parameter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39730.