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ABSTRACT: Atmospheric depositions have increased substantially since industrialisation and have affected many forest properties. Forest
soils of low buffering to the acid load as those of sandy or silty texture significantly declined in soil pH and some essential
nutrients during the last decades (see Chap. 21) causing a controversial discussion about the stability of such forest ecosystems (Ulrich 1981, 1987, 1992, 1994b). Of 1,700
soils studied in the forest soil survey programme of Germany, 60% of all soils have pH(H2O) <4.2 (Wolff and Riek 1997a, b). N deficiency, which has been a common feature of forest stands in the temperate region
(Tamm 1991), does not occur any more due to high N deposition rates in Europe (except of north and east Europe). On the contrary,
the N supply has increased as indicated by high N contents of the tree foliage and surface organic layer samples (Tietema
and Beier 1995; Alewell et al. 2000b; McNulty et al. 1991; Wolff and Riek 1997a). Nitrate losses with seepage water have increased
at some locations (Dise and Wright 1995; Bredemeier et al. 1998; Matzner et al. 2004; Borken and Matzner 2004), which led
to a discussion about the saturation of forests with nitrogen (e.g. Ågren and Bosatta 1988; Tamm 1991; Gundersen et al. 1998;
Aber et al. 1998). However, political actions by European countries have led to a noticeable decline in atmospheric depositions
of sulphur and nitrogen in the 1980s and 1990s (Ferrier et al. 2001) raising questions about the recovery of forest ecosystems
from soil acidification. A general recovery of alkalinity of lakes and streams was observed in all regions of Europe in the
1990s (Stoddard et al. 1999) except at many sites in central Europe where a significant delay in aquatic recovery from acidification
(Alewell et al. 2000a) was observed. Recovery of water acidification can take decades, because of the release of previously
stored sulphate from soils with a high storage capacity for sulphate continues leading to acidification of aquatic systems
(Matzner 2004). Moreover, many of the European forest stands are experiencing changes due to the so-called “climate change”
phenomenon. For example, significant changes in the climate at the Solling site with increased air temperature and precipitation
have been recorded since the Solling project was established in 1966 (see Chap. 2). All these impacts on forest ecosystems constitute the basis for extensive research for which the most promising tool is
the long-term monitoring of element budgets of representative ecosystems. This allows one to follow forest development under
changing environmental conditions.
12/2008: pages 303-336;
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ABSTRACT: The functional properties of the Vps10p-domain receptor SorCS3 are undescribed. Here, we examine its processing and sorting in cellular transfectants, and analyze the binding of potential ligands to the purified receptor. We show that SorCS3 is synthesized as a proprotein and converted to its mature form by N-terminal propeptide cleavage in distal Golgi compartments. The propeptide is not a requirement for normal processing of the receptor and does not prevent ligands from binding to the SorCS3 precursor form. Expression of wt and chimeric receptors further suggests that SorCS3 predominates on the plasma membrane, exhibits slow internalization and does not engage in intracellular trafficking. SorCS3 emerges as a new neurotrophin binding Vps10p-domain receptor functionally distinct from its relatives Sortilin and SorLA.
FEBS Letters 03/2005; 579(5):1172-6. · 3.54 Impact Factor
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ABSTRACT: The 39 kDa receptor-associated protein (RAP) is a three-domain escort protein in the secretory pathway for several members of the low-density lipoprotein receptor (LDLR) family of endocytic receptors, including the LDLR-related protein (LRP). The minimal functional unit of LRP required for efficient binding to RAP is composed of complement-type repeat (CR)-domain pairs, located in clusters on the extracellular part of LRP. Here we investigate the binding of full-length RAP and isolated RAP domains 1-3 to an ubiquitin-fused CR-domain pair consisting of the fifth and sixth CR domains of LRP (U-CR56). As shown by isothermal titration calorimetric analysis of simple RAP domains as well as adjoined RAP domains, all three RAP domains bind to this CR-domain pair in a noncooperative way. The binding of U-CR56 to RAP domains 1 and 2 is (at room temperature) enthalpically driven with an entropy penalty (K(D) = 2.77 x 10(-6) M and 1.85 x 10(-5) M, respectively), whereas RAP domain 3 binds with a substantially lower enthalpy, but is favored due to a positive entropic contribution (K(D) = 1.71 x 10(-7) M). The heat capacity change for complex formation between RAP domain 1 and the CR-domain pair is -1.65 kJ K(-1) mol(-1). There is an indication of a conformational change in RAP domain 3 upon binding in the surface plasmon resonance analysis of the interaction. The different mechanisms of binding to RAP domains 1 and 3 are further substantiated by the different effects on binding of mutations of the Asp and Trp residues in the LRP CR5 or CR6 domains, which are important for the recognition of several ligands.
Biochemistry 01/2002; 40(50):15408-17. · 3.42 Impact Factor
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A Nykjaer,
J C Fyfe,
R Kozyraki,
J R Leheste, C Jacobsen,
M S Nielsen,
P J Verroust,
M Aminoff,
A de la Chapelle,
S K Moestrup,
R Ray,
J Gliemann,
T E Willnow,
E I Christensen
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ABSTRACT: Steroid hormones are central regulators of a variety of biological processes. According to the free hormone hypothesis, steroids enter target cells by passive diffusion. However, recently we demonstrated that 25(OH) vitamin D(3) complexed to its plasma carrier, the vitamin D-binding protein, enters renal proximal tubules by receptor-mediated endocytosis. Knockout mice lacking the endocytic receptor megalin lose 25(OH) vitamin D(3) in the urine and develop bone disease. Here, we report that cubilin, a membrane-associated protein colocalizing with megalin, facilitates the endocytic process by sequestering steroid-carrier complexes on the cellular surface before megalin-mediated internalization of the cubilin-bound ligand. Dogs with an inherited disorder affecting cubilin biosynthesis exhibit abnormal vitamin D metabolism. Similarly, human patients with mutations causing cubilin dysfunction exhibit urinary excretion of 25(OH) vitamin D(3). This observation identifies spontaneous mutations in an endocytic receptor pathway affecting cellular uptake and metabolism of a steroid hormone.
Proceedings of the National Academy of Sciences 12/2001; 98(24):13895-900. · 9.68 Impact Factor
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ABSTRACT: Cubilin is a 460-kDa protein functioning as an endocytic receptor for intrinsic factor vitamin B(12) complex in the intestine and as a receptor for apolipoprotein A1 and albumin reabsorption in the kidney proximal tubules and the yolk sac. In the present study, we report the identification of cubilin as a novel transferrin (Tf) receptor involved in catabolism of Tf. Consistent with a cubilin-mediated endocytosis of Tf in the kidney, lysosomes of human, dog, and mouse renal proximal tubules strongly accumulate Tf, whereas no Tf is detectable in the endocytic apparatus of the renal tubule epithelium of dogs with deficient surface expression of cubilin. As a consequence, these dogs excrete increased amounts of Tf in the urine. Mice with deficient synthesis of megalin, the putative coreceptor colocalizing with cubilin, also excrete high amounts of Tf and fail to internalize Tf in their proximal tubules. However, in contrast to the dogs with the defective cubilin expression, the megalin-deficient mice accumulate Tf on the luminal cubilin-expressing surface of the proximal tubule epithelium. This observation indicates that megalin deficiency causes failure in internalization of the cubilin-ligand complex. The megalin-dependent, cubilin-mediated endocytosis of Tf and the potential of the receptors thereby to facilitate iron uptake were further confirmed by analyzing the uptake of (125)I- and (59)Fe-labeled Tf in cultured yolk sac cells.
Proceedings of the National Academy of Sciences 11/2001; 98(22):12491-6. · 9.68 Impact Factor
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ABSTRACT: The low-density-lipoprotein-receptor (LDLR)-related protein (LRP) is composed of several classes of domains, including complement-type repeats (CR), which occur in clusters that contain binding sites for a multitude of different ligands. Each approximately 40-residue CR domain contains three conserved disulphide linkages and an octahedral Ca(2+) cage. LRP is a scavenging receptor for ligands from extracellular fluids, e.g. alpha(2)-macroglobulin (alpha(2)M)-proteinase complexes, lipoprotein-containing particles and serine proteinase-inhibitor complexes, like the complex between urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitor-1 (PAI-1). In the present study we analysed the interaction of the uPA-PAI-1 complex with an ensemble of fragments representing a complete overlapping set of two-domain fragments accounting for the ligand-binding cluster II (CR3-CR10) of LRP. By ligand blotting, solid-state competition analysis and surface-plasmon-resonance analysis, we demonstrate binding to multiple CR domains, but show a preferential interaction between the uPA-PAI-1 complex and a two-domain fragment comprising CR domains 5 and 6 of LRP. We demonstrate that surface-exposed aspartic acid and tryptophan residues at identical positions in the two homologous domains, CR5 and CR6 (Asp(958,CR5), Asp(999,CR6), Trp(953,CR5) and Trp(994,CR6)), are critical for the binding of the complex as well as for the binding of the receptor-associated protein (RAP) - the folding chaperone/escort protein required for transport of LRP to the cell surface. Accordingly, the present work provides (1) an identification of a preferred binding site within LRP CR cluster II; (2) evidence that the uPA-PAI-1 binding site involves residues from two adjacent protein domains; and (3) direct evidence identifying specific residues as important for the binding of uPA-PAI-1 as well as for the binding of RAP.
Biochemical Journal 08/2001; 357(Pt 1):289-96. · 4.90 Impact Factor
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ABSTRACT: We previously isolated and sequenced the approximately 250-kDa type 1 receptor sorLA/LR11, a mosaic protein with elements characterizing the Vps10p domain receptor family as well as the low density lipoprotein receptor family. The N terminus of the Vps10p domain comprises a consensus sequence for cleavage by furin ((50)RRKR(53)) that precedes a truncation found in sorLA isolated from human brain. Here we show that sorLA, like sortilin-1/neurotensin receptor-3, whose lumenal domain consists of a Vps10p domain only, is synthesized as a proreceptor that is cleaved by furin in late Golgi compartments. We show that the truncation conditions the Vps10p domain for propeptide inhibitable binding of neuropeptides and the receptor-associated protein. We further demonstrate that avid binding of the receptor-associated protein, apolipoprotein E, and lipoprotein lipase not inhibited by propeptide occurs to sites located in other lumenal domains. In transfected cells, about 10% of full-length sorLA were expressed on the cell surface capable of mediating endocytosis. However, the major pool of receptors was found in late Golgi compartments, suggesting possible interaction with newly synthesized ligands. The results show that sorLA, following activation by truncation, binds multiple ligands and may mediate both endocytosis and sorting.
Journal of Biological Chemistry 07/2001; 276(25):22788-96. · 4.77 Impact Factor
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ABSTRACT: Clara cell secretory protein (CCSP) is a transport protein for lipophilic substances in bronchio-alveolar fluid, plasma, and uterine secretion. It acts as a carrier for steroid hormones and polychlorinated biphenyl metabolites. Previously, the existence of receptors for uptake of CCSP.ligand complexes into the renal proximal tubules had been suggested. Using surface plasmon resonance analysis, we demonstrate that CCSP binds to cubilin, a peripheral membrane protein on the surface of proximal tubular cells. Binding to cubilin results in uptake and lysosomal degradation of CCSP in cultured cells. Surprisingly, internalization of CCSP is blocked not only by cubilin antagonists but also by antibodies directed against megalin, an endocytic receptor that does not bind CCSP but associates with cubilin. Consistent with a role of both receptors in renal uptake of CCSP in vivo, patients deficient for cubilin or mice lacking megalin exhibit a defect in tubular uptake of the protein and excrete CCSP into the urine. These findings identify a cellular pathway consisting of a CCSP-binding protein (cubilin) and an endocytic coreceptor (megalin) responsible for tissue-specific uptake of CCSP and associated ligands.
Journal of Biological Chemistry 05/2001; 276(16):13295-301. · 4.77 Impact Factor
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ABSTRACT: Intravascular haemolysis is a physiological phenomenon as well as a severe pathological complication when accelerated in various autoimmune, infectious (such as malaria) and inherited (such as sickle cell disease) disorders. Haemoglobin released into plasma is captured by the acute phase protein haptoglobin, which is depleted from plasma during elevated haemolysis. Here we report the identification of the acute phase-regulated and signal-inducing macrophage protein, CD163, as a receptor that scavenges haemoglobin by mediating endocytosis of haptoglobin-haemoglobin complexes. CD163 binds only haptoglobin and haemoglobin in complex, which indicates the exposure of a receptor-binding neoepitope. The receptor-ligand interaction is Ca2+-dependent and of high affinity. Complexes of haemoglobin and multimeric haptoglobin (the 2-2 phenotype) exhibit higher functional affinity for CD 163 than do complexes of haemoglobin and dimeric haptoglobin (the 1-1 phenotype). Specific CD163-mediated endocytosis of haptoglobin-haemoglobin complexes is measurable in cells transfected with CD163 complementary DNA and in CD163-expressing myelo-monocytic lymphoma cells.
Nature 02/2001; 409(6817):198-201. · 36.28 Impact Factor
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ABSTRACT: The effect of the water-dispersible tocopherol preparation, Grindox 1032, and the oil-soluble tocopherol preparation, Toco 70, on oxidative stability in fish oil-enriched mayonnaise was examined. The two commercial antioxidant preparations were supplemented in different levels corresponding to 20-280 ppm tocopherol in addition to the 600 ppm present in the oils used for the mayonnaise. The oxidative stability was assessed by sensory analysis, the tendency of formation of free radicals, and concentrations of lipid hydroperoxides and volatile oxidation products. The effect of tocopherol on oxidation depended on the nature and the concentration of the tocopherol preparation employed, and it also depended on the parameters evaluated. Addition of high levels of Grindox 1032 (~140-280 ppm tocopherol) thus decreased the intensity of rancid off-flavor, but increased the formation of fishy off-flavors, the tendency of free radical formation and the concentration of certain volatiles. In contrast, low levels of Grindox 1032 (<70 ppm tocopherol) reduced the concentration of some volatiles, but did not seem to influence the off-flavor profile of the mayonnaise. Toco 70, which was only supplemented in low levels (<40 ppm tocopherol) increased the tendency for free radical formation, changed the profile of volatiles, and did not have a clear effect on the fishy and rancid off-flavor formation. Thus, additional tocopherol did not appear to be an efficient antioxidant in fish oil-enriched mayonnaise, perhaps because it cannot prevent the metal-catalyzed decomposition of peroxides, which we previously suggested to play an important role in mayonnaise.
European Food Research and Technology 01/2001; 212(3):308-318. · 1.57 Impact Factor
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ABSTRACT: The kidney is a major organ for uptake of the thyroid hormone thyroxine (T(4)) and its conversion to the active form, triiodothyronine. In the plasma, one of the T(4) carriers is transthyretin (TTR). In the present study we observed that TTR, the transporter of both T(4) and retinol-binding protein, binds to megalin, the multiligand receptor expressed on the luminal surface of various epithelia including the renal proximal tubules. In the kidney, megalin plays an important role in tubular uptake of macromolecules filtered through the glomerulus. To evaluate the importance of megalin for renal uptake of TTR, we performed binding/uptake assays using immortalized rat yolk sac cells with high expression levels of megalin. Radiolabeled TTR, free as well as in complex with thyroxine or retinol-binding protein, was rapidly taken up by the cells, and the uptake was strongly inhibited by a polyclonal megalin antibody and by the receptor-associated protein, a chaperone-like protein inhibiting ligand binding to megalin. In cell culture, different TTR mutations presented different levels of cell association and degradation, suggesting that the structure of TTR is important for megalin recognition. Both the apo form and the T(4)-bound form were taken up by the cells. Analysis of urine from patients with Dent's disease, a renal tubular disorder that alters receptor-mediated endocytic reabsorption of proteins, identified TTR as an abundant excreted protein. Furthermore, analysis of kidney sections of megalin-deficient mice revealed no immunohistochemical TTR labeling in intracellular vesicles in the proximal tubule cells when compared with wild type control littermates. Taken together, the present data indicate that TTR represents a novel megalin ligand of importance in the thyroid hormone homeostasis.
Journal of Biological Chemistry 01/2001; 275(49):38176-81. · 4.77 Impact Factor
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ABSTRACT: C-type lectin-like domains are found in many proteins, where they mediate binding to a wide diversity of compounds, including carbohydrates, lipids, and proteins. The binding of a C-type lectin-like domain to a ligand is often influenced by calcium. Recently, we have identified a site in the C-type lectin-like domain of tetranectin, involving Lys-148, Glu-150, and Asp-165, which mediates calcium-sensitive binding to plasminogen kringle 4. Here, we investigate the effect of conservative substitutions of these and a neighboring amino acid residue. Substitution of Thr-149 in tetranectin with a tyrosine residue considerably increases the affinity for plasminogen kringle 4, and, in addition, confers affinity for plasminogen kringle 2. As shown by isothermal titration calorimetry analysis, this new interaction is stronger than the binding of wild-type tetranectin to plasminogen kringle 4. This study provides further insight into molecular determinants of importance for binding selectivity and affinity of C-type lectin kringle interactions.
Journal of Biological Chemistry 01/2001; 275(48):37390-6. · 4.77 Impact Factor
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ABSTRACT: The low-density lipoprotein receptor-related protein (LRP) is a large surface receptor that mediates binding and internalization of a large number of structurally and functionally unrelated ligands. The ligand binding sites are located in clusters of complement-type repeats (CR), where the general absence of mutual binding competition suggests that different ligands map to distinct sites. Binding of alpha(2)-macroglobulin-protease complexes to the LRP is mediated by the receptor binding domain (RBD) of alpha(2)-macroglobulin (alpha(2)M). To determine the major binding epitope(s) in the LRP, we generated a complete set of tandem CR proteins spanning the second cluster of CR domains, and identified a binding site for alpha(2)M in the N-terminal part of the cluster comprising CR3-CR6, using ligand blotting and surface plasmon resonance (SPR) analysis. The specific site involved in alpha(2)M recognition resides in the fourth CR domain, CR4, whereas another site is identified in CR5. An acidic epitope in CR4 is identified as important for binding alpha(2)M by mutagenesis and SPR analysis. The formation of the complex between the rat alpha(1)-macroglobulin RBD and CR domain pairs is characterized by analytical size-exclusion chromatography, which demonstrates a sufficiently strong interaction between the alpha(1)M RBD and CR34 or CR45 for the isolation of a complex.
Biochemistry 10/2000; 39(35):10627-33. · 3.42 Impact Factor
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ABSTRACT: Megaloblastic anemia 1 (MGA1) is an autosomal recessive disorder caused by the selective intestinal malabsorption of intrinsic factor (IF) and vitamin B(12)/cobalamin (Cbl) in complex. Most Finnish patients with MGA1 carry the disease-specific P1297L mutation (FM1) in the IF-B(12) receptor, cubilin. By site-directed mutagenesis, mammalian expression, and functional comparison of the purified wild-type and FM1 mutant forms of the IF-Cbl-binding cubilin region (CUB domains 5-8, amino acid 928-1386), we have investigated the functional implications of the P1297L mutation. Surface plasmon resonance analysis revealed that the P1297L substitution specifically increases the K(d) for IF-Cbl binding several-fold, largely by decreasing the association rate constant. In agreement with the binding data, the wild-type protein, but not the FM1 mutant protein, potently inhibits 37 degrees C uptake of iodine 125-IF-Cbl in cubilin-expressing epithelial cells. In conclusion, the data presented show a substantial loss in affinity of the FM1 mutant form of the IF-Cbl binding region of cubilin. This now explains the malabsorption of Cbl and Cbl-dependent anemia in MGA1 patients with the FM1 mutation. (Blood. 2000;96:405-409)
Blood 08/2000; 96(2):405-9. · 9.90 Impact Factor
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ABSTRACT: The low density lipoprotein receptor-related protein (LRP), a member of the low density lipoprotein receptor family, mediates the internalization of a diverse set of ligands. The ligand binding sites are located in different regions of clusters consisting of approximately 40 residues, cysteine-rich complement-type repeats (CRs). The 39-40-kDa receptor-associated protein, a folding chaperone/escort protein required for efficient transport of functional LRP to the cell surface, is an antagonist of all identified ligands. To analyze the multisite inhibition by RAP in ligand binding of LRP, we have used an Escherichia coli expression system to produce fragments of the entire second ligand binding cluster of LRP (CR3-10). By ligand affinity chromatography and surface plasmon resonance analysis, we show that RAP binds to all two-repeat modules except CR910. CR10 differs from other repeats in cluster II by not containing a surface-exposed conserved acidic residue between Cys(IV) and Cys(V). By site-directed mutagenesis and ligand competition analysis, we provide evidence for a crucial importance of this conserved residue for RAP binding. We provide experimental evidence showing that two adjacent complement-type repeats, both containing a conserved acidic residue, represent a minimal unit required for efficient binding to RAP.
Journal of Biological Chemistry 08/2000; 275(28):21017-24. · 4.77 Impact Factor
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European Food Research and Technology 06/2000; 211(2):86-98. · 1.57 Impact Factor
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ABSTRACT: Using affinity chromatography and surface plasmon resonance analysis, we have identified cubilin, a 460-kDa receptor heavily expressed in kidney proximal tubule epithelial cells, as an albumin binding protein. Dogs with a functional defect in cubilin excrete large amounts of albumin in combination with virtually abolished proximal tubule reabsorption, showing the critical role for cubilin in the uptake of albumin by the proximal tubule. Also, by immunoblotting and immunocytochemistry we show that previously identified low-molecular-weight renal albumin binding proteins are fragments of cubilin. In addition, we find that mice lacking the endocytic receptor megalin show altered urinary excretion, and reduced tubular reabsorption, of albumin. Because cubilin has been shown to colocalize and interact with megalin, we propose a mechanism of albumin reabsorption mediated by both of these proteins. This process may prove important for understanding interstitial renal inflammation and fibrosis caused by proximal tubule uptake of an increased load of filtered albumin.
Journal of Clinical Investigation 06/2000; 105(10):1353-61. · 15.39 Impact Factor
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ABSTRACT: We recently reported the identification of human calumenin, a novel Ca(2+) binding, transformation-sensitive and secreted protein [Vorum et al. (1998) Biochim. Biophys. Acta 1386, 121-131; Vorum et al. (1999) Exp. Cell Res. 248, 473-481] belonging to the family of multiple EF-hand proteins of the secretory pathway that include reticulocalbin, ERC-55, Cab45 and crocalbin. In order to further investigate the extracellular functions of calumenin we immobilized the recombinant protein to a column. After application of a placental tissue extract we were able to elute one protein that interacts with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues.
FEBS Letters 02/2000; 465(2-3):129-34. · 3.54 Impact Factor
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Charlotte Jacobsen,
Karsten Hartvigsen,
Pia Lund,
Jens Adler-Nissen,
Gunhild Hølmer,
Anne S Meyer, C Jacobsen,
K Hartvigsen,
P Lund,
G Hølmer,
J Adler-Nissen,
A S Meyer
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ABSTRACT: Oxidative protection of mayonnaises with 16% fish oil was studied during cold storage (5 7C) after supplementation with different tocopherol systems: the ternary antioxidant system ascorbic acid, lecithin and tocopherol (A/L/T), and two commercial mixtures, an oil-soluble (Toco 70) preparation and a water-soluble (Grindox 1032) preparation. The physical structure of the fish-oil-enriched mayonnaise was manipulated by adding extra emulsifier (Panodan TR) with the purpose of investigating whether or not this affected the antiox-idative activity of the tocopherol mixtures. A number of different analytical techniques HPLC (high-perform-ance liquid chromatography, gas chromatography mass spectrometry (GC-MS), sensory analysis, confocal laser scanning microscopy and rheological measure-ments) were employed to elucidate the chemical, senso-ry, structural and rheological aspects of the oxidation process. Discriminant partial least squares regression was used to analyse the data obtained. The three toco-pherol preparations not only affected the oxidative sta-bility of the mayonnaises differently, they also in-fluenced the rheological and structural properties of the mayonnaises in different ways. The rheological and structural properties of the mayonnaise were also af-fected by the addition of extra emulsifier, but this did not influence the formation of fishy and rancid off-fla-vours. Addition of the A/L/T system caused the imme-diate formation of distinct fishy and rancid off-flavours in the fresh mayonnaises. The volatile compounds trans-2-heptenal, 4-octen-3-one, 1-octen-3-ol, trans,cis-2,4-heptadienal, trans,trans-2,4-heptadienal, trans-2-oc-tenal, nonanal and trans,cis-2,6-nonadienal were thought to contribute to the fishy and rancid flavours. Addition of Toco 70 did not affect the sensory percep-tion of mayonnaise nor the development of volatile off-flavour compounds as evaluated by GC-MS, but the peroxide values were slightly increased in mayonnaise containing Toco 70 as compared to the other mayon-naises. Mayonnaise with Grindox 1032 seemed to have fewer fishy and rancid off-flavours than mayonnaises without antioxidant. This flavour-protective effect of Grindox 1032 was correlated to an increase in the size of the droplet diameter of mayonnaises supplemented with Grindox 1032.
European Food Research and Technology 01/2000; 210:242-257. · 1.57 Impact Factor
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ABSTRACT: A number of different analytical techniques (HPLC, GC-MS, sensory analysis, laser diffraction droplet size determination,
confocal laser scanning microscopy and rheological measurements) were employed to elucidate both chemical, sensory, structural
and rheological aspects of the oxidation process in mayonnaise containing 16% fish oil. The primary focus of the study was
on the antioxidative effect of two different types of commercial propyl gallate mixtures: an oil-soluble and a water-soluble
preparation. The effect of adding extra emulsifier (Panodan TR), used to manipulate the physical structure of the fish-oil-enriched
mayonnaise and in turn affect the antioxidative activity of the propyl gallate mixtures, was also investigated. Mayonnaise
with fish oil did not oxidise faster than mayonnaise without fish oil when judged from the chemical parameters tested. However,
the fish-oil-enriched mayonnaises developed unpleasant off-odours and off-flavours much faster than the mayonnaise without
fish oil. Addition of the two different propyl gallate mixtures not only influenced negatively the sensory qualities but also
affected the structure and the rheological properties of the mayonnaise. Propyl gallate thus, in particular, promoted the
development of fishy and rancid off-flavours during the storage of mayonnaise with fish oil, and this effect was especially
pronounced for the water-soluble propyl gallate mixture. Four volatile oxidation compounds, namely 3-furaldehyde, 2,4-heptadienal,
2,4-decadienal and ethyl benzene, appeared to correlate to the fishy and rancid off-flavours that developed in mayonnaises
with propyl gallate. Addition of propyl gallate also resulted in increased peroxide values, and a less viscous mayonnaise
with bigger droplets. The data thus demonstrated that the propyl gallate mixtures employed did not protect mayonnaise with
fish oil against flavour deterioration due to oxidation during storage. In addition, the data showed that several structural
and rheological parameters were affected by the addition of propyl gallate.
European Food Research and Technology 10/1999; 210(1):13-30. · 1.57 Impact Factor
