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  • 1. Anker, M.
    et al.
    Stading, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Aging of whey protein films and the effect on mechanical and barrier properties2001Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 49, nr 2, s. 989-995Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work focuses on the aging of whey protein isolate (WPI) films plasticized with glycerol (G) and sorbitol (S). The films were cast from heated aqueous solutions at pH 7 and dried at 23 °C and 50% relative humidity (RH) for 16 h. They were stored in a climate room (23 °C, 50% RH) for 120 days, and the film properties were measured at regular intervals. The moisture content (MC) of the WPI/G films decreased from 22% (2 days) to 15% (45 days) and was thereafter constant at 15% (up to 120 days). This affected the mechanical properties and caused an increased stress at break (from 2.7 to 8.3 MPa), a decreased strain at break (from 33 to 4%), and an increased glass transition temperature (T g) (from -56 to -45 °C). The barrier properties were, however, unaffected, with constant water vapor permeability and a uniform film thickness. The MC of the WPI/S films was constant at ?9%, which gave no change in film properties.

  • 2. Anker, M.
    et al.
    Stading, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Effects of pH and the gel state on the mechanical properties, moisture contents, and glass transition temperatures of whey protein films1999Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 47, nr 5, s. 1878-1886Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanical properties, moisture contents (MC), and glass transition temperature (T(g)) of whey protein isolate (WPI) films were studied at various pH values using sorbitol (S) as a plasticizer. The films were cast from heated aqueous solutions and dried in a climate chamber at 23 °C and 50% relative humidity (RH) for 16 h. The critical gel concentrations (c(g)) for the cooled aqueous solutions were found to be 11.7, 12.1, and 11.3% (w/w) WPI for pH 7, 8, and 9, respectively. The cooling rate influenced the c(g), in that a lower amount of WPI was needed for gelation when a slower cooling rate was applied. Both cooling rates used in this study showed a maximum in the c(g) at pH 8. The influence of the polymer network on the film properties was elucidated by varying the concentration of WPI over and under the c(g). Strain at break (?(b)) showed a maximum at the c(g) for all pH values, thus implying that the most favorable structure regarding the ability of the films to stretch is formed at this concentration. Young's modulus (E) and stress at break (?(b)) showed a maximum at c(g) for pH 7 and 8. The MC and ?(b) increased when pH increased from 7 to 9, whereas T(g) decreased. Hence, T(g) values were -17, -18, and -21 °C for pH 7, 8, and 9, respectively. E and ?(b) decreased and ?(b) and thickness increased when the surrounding RH increased. The thickness of the WPI films also increased with the concentration of WPI.

  • 3. Anker, M.
    et al.
    Stading, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Mechanical Properties, Water Vapor Permeability, and Moisture Contents of ?-Lactoglobulin and Whey Protein Films Using Multivariate Analysis1998Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 46, nr 5, s. 1820-1829Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical and barrier properties of ?-lactoglobulin (?-Lg) and whey protein isolate (WPI) films were studied using sorbitol (S) as a plasticizer. The films were cast from heated aqueous solutions and dried in a climate chamber at 23 °C and 50% relative humidity for 16 h. The multivariate analysis used has proved to be a valuable tool for evaluating and quantifying the influences of the variables in the specified experimental domain. Two identical factorial designs were applied to evaluate the influence of the concentration of ?-Lg and WPI, the concentration of S, and the pH. The two materials, ?-Lg and WPI, show similar results, which can be attributed to the dominating protein ?-lactoglobulin. At pH 9, Young's modulus and stress at break are not affected when the concentration of ?-Lg, WPI, or S varies. At pH 7 and 8, Young's modulus and stress at break increase when the concentration of ?-Lg and WPI increases, and they decrease when the concentration of S increases. Strain at break increases when pH increases from 7 to 9, a more pronounced effect being observed for the WPI films. Water vapor permeability (WVP) decreases and increases for pH 7 and 9, respectively, as the concentration of ?-Lg and WPI increases. This contrast in behavior at different pH values is probably due to a structural difference that occurs above pH 8. Moisture content and WVP increase when S increases. Here a clear distinction can be observed between the two film materials: the ?-Lg films show higher values for both moisture content and WVP measurements.

  • 4. Anker, M.
    et al.
    Stading, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Relationship between the microstructure and the mechanical and barrier properties of whey protein films2000Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 48, nr 9, s. 3806-3816Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work was focused on the relationship between the microstructure and the mechanical and barrier properties of whey protein isolate (WPI) films. Sorbitol (S) and glycerol (G) were used as plasticizers and the pH was varied between 7 and 9. The films were cast from heated aqueous solutions and dried in a climate room at 23 °C and 50% relative humidity for 16 h. The microstructure of the films was found to be dependent on the concentration, the plasticizers, and the pH. When the concentration increased, a more aggregated structure was formed, with a denser protein network and larger pores. This resulted in increased water vapor permeability (WVP) and decreased oxygen permeability (OP). When G was used as a plasticizer instead of S, the microstructure was different, and the moisture content and WVP approximately doubled. When the pH increased from 7 to 9, a denser protein structure was formed, the strain at break increased, and the OP decreased.

  • 5. Borjesson, T.S.
    et al.
    Stollman, U.M.
    Schnurer, J.L.
    Off-odorous compounds produced by molds on oatmeal agar.: Identification and relation to other growth characteristics1993Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 41, nr 11, s. 2104-2111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ten Penicillium and Aspergillus species, four with a strong musty off-odor and six reference fungi without any characteristic odor, were cultivated on oatmeal agar for 5 days in cultivation vessels provided with an inlet and an outlet for air. Samples of volatile metabolites were collected on a porous polymer adsorbent attached to the outlet from day 2 through day 5 after inoculation. Adsorbed compounds were desorbed thermally and analyzed with GC/MS and a combined GC and sensory analysis, the GC sniff technique. Multivariate analysis of GC/MS and fungal odor data revealed strong associations between 6 of 65 volatile compounds and musty off-odor. The GC sniff technique showed that five of these, dimethyl disulfide, 1-octen-3-ol, 2-methylisoborneol, and two C11H18 compounds, had prominent off-odors. In addition, geosmin, 1-methoxy-3-methylbenzene, and methylphenol were produced in large amounts by some off-odorous fungi and contributed to their unpleasant odor. 3-Methylfuran, 2-methyl-1-propanol, and 3-methyl-1-butanol were much more commonly produced than the off-odorous compounds. Both odorous and other volatile metabolites could be detected after 2 days of fungal growth. The production of odorous metabolites was enhanced at the time of sporulation. © 1993 American Chemical Society.

  • 6. Cho, S.-W.
    et al.
    Gällstedt, Mikael
    RISE., Innventia.
    Hedenqvist, M.S.
    RISE., Innventia.
    Properties of wheat gluten/poly(lactic acid) laminates2010Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 58, nr 12, s. 7344-7350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WG films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 °C instead of 110 °C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 °C) did not, however, have a major effect on the final peel strength.

  • 7. Ehn, B.-M.
    et al.
    Allmere, T.
    Telemo, E.
    Bengtsson, U.
    Ekstrand, Bo
    SIK – Institutet för livsmedel och bioteknik.
    Modification of IgE binding to beta-lactoglobulin by fermentation and Proteolysis of cow's milk2005Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 53, nr 9, s. 3743-3748Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of fermentation by Lactobacilliand of proteolytic hydrolysis of whole milk on the IgE binding ability of ?-lactoglobulin was studied using an ELISA inhibition assay. Sera from nine adult milk allergic patients were tested. The individual sera showed a similar inhibition pattern in the changes during fermentation and proteolysis. The degradation of ?-lactoglobulin was studied with liquid chromatography. In general, fermentation with Lactobacilli gave little effect on IgE binding, even though chromatography data showed a gradual degradation of ?-lactoglobulin. Proteolysis with trypsin, however, gave extensive degradation of ?-lactoglobulin and strongly decreased IgE binding. In addition, we measured the inhibition pattern of ?-lactoglobulin in various selected commercially available fermented milk products. These showed an IgE binding capacity similar to that of nonfermented high pasteurized milk. © 2005 American Chemical Society.

  • 8. Ehn, B.-M.
    et al.
    Ekstrand, Bo
    SIK – Institutet för livsmedel och bioteknik.
    Bengtsson, U.
    Ahlstedt, S.
    Modification of IgE Binding during Heat Processing of the Cow's Milk Allergen ?-Lactoglobulin2004Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 52, nr 5, s. 1398-1403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of heat treatment on the IgE binding ability of ?-lactoglobulin, as pure protein or in whole milk, was studied by inhibition of IgE antibody binding using FEIA-CAP inhibition. A slight but significant decreased IgE binding was seen between unheated and heat-treated ?-lactoglobulin solution at 74 °C (IC50 = 2.03 and 3.59 ?g/mL, respectively, p = 0.032). A more pronounced decrease was found at 90 °C with an IC50 of 8.45 ?g/mL (p = 0.014). The inhibition of IgE binding of milk after heat treatment at 90 °C was also significantly decreased (p = 0.007). However, at all heat treatments, a similar total amount of IgE antibodies could be inhibited at a sufficiently high concentration of ?-lactoglobulin. The inhibiting ability of ?-lactoglobulin was significantly impaired in some fermented acidified milk products such as yogurt as compared to that in nonfermented milk (p < 0.001). There was only a small difference of IgE binding between the native forms of genetic variants A and B.

  • 9. Einarsson, H.
    et al.
    Snygg, Bengt Göran
    SIK – Svenska livmedelsinstitutet.
    Eriksson, Caj
    SIK – Svenska livmedelsinstitutet.
    Inhibition of bacterial growth by Maillard reaction products1983Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 31, nr 5, s. 1043-1047Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Maillard reaction products (MRP) were obtained by refluxing solutions containing either arginine and xylose (AX) or histidine and glucose (HG). The solutions were tested either unfractionated or partly purified by dialysis through a Spectra/Por (R)-6 membrane with a molecular weight cutoff at 1000. The bacteria tested were both pathogenic and spoilage bacteria frequently found in food. The effects of the AX and HG added were assessed on the basis of the growth curves and the MIC (minimum inhibitory concentration) values recorded. The MIC values obtained show that the inhibitory effect of MRP is dependent on the type of MRP and type of bacteria used. As can be seen from the growth curves, the lag phase of the growth was prolonged with increased concentrations of MRP. The results of the dialysis show that the high molecular weight fraction (Mr ?1000) was more inhibitory than the low molecular weight fraction (Mr ?1000) when tested with Bacillus subtilis, Escherichia coli, and Staphylococcus aureus. The MRP used in this study have in other studies been shown to possess a high antioxidative effect. © 1983 American Chemical Society.

  • 10.
    Ekstrand, Bo
    et al.
    SIK – Svenska livmedelsinstitutet.
    Bjorck, L.
    Oxidation of beta-carotene by bovine milk lactoperoxidase-halide-hydrogen peroxide systems1986Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 34, nr 3, s. 412-415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The halide-mediated peroxidase-catalyzed oxidation of ?-carotene was studied as a model system for lipid peroxidation. Of the halide ions tested, Br-, I-, and SCN- all caused some degree of ?-carotene oxidation at pH 7.0 and 4.4. No oxidation was observed with Cl-, however, which is consistent with Cl- not being a substrate for lactoperoxidase. The ?-carotene oxidation caused by the lactoperoxidase-I--H2O2 system was pH dependent, the rate of oxidation being 100-fold higher at pH 4.4 than at pH 7.0. When both I- and SCN- were present, the oxidation rate was reduced. At least partially, this interference between the two substrates was due to competition for the substrate-binding sites on the enzyme. © 1986 American Chemical Society.

  • 11.
    Eriksson, Caj
    SIK – Svenska livmedelsinstitutet.
    Aroma compounds derived from oxidized lipids.: Some biochemical and analytical aspects1975Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 23, nr 2, s. 126-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation of aliphatic aldehydes and alcohols, primarily from unsaturated fatty acids with the participation of lipoxygenase, hemoproteins, alcohol dehydrogenase, and esterase, is briefly reviewed with special regard to plant foods. The controlling or avoiding of aldehyde formation in food systems by the use of alcohol dehydrogenase and of certain sugar-aminc acid reaction products was studied, by use of a gas Chromatographic technique.

  • 12. Gao, C.
    et al.
    Stading, Mats
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Wellner, N.
    Parker, M.L.
    Noel, T.R.
    Mills, E.N.C.
    Plasticization of a protein-based film by glycerol: A spectroscopic, mechanical, and thermal study2006Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 54, nr 13, s. 4611-4616Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kafirin, the seed storage protein of the cereal sorghum, is highly homologous with the maize storage protein zein. The effects of plasticisation of a kafirin film by glycerol in the absence of water were examined by a combination of spectroscopic (NMR and infrared), rheological, and calorimetric methods. The results suggest that at low glycerol levels the glycerol is absorbed onto and possibly into the protein. Increasing the level of glycerol increases the motion of the protein and changes the protein conformation. There are corresponding changes of the mechanical properties of protein films. At 40% (w/w) of glycerol, two glass transition temperatures were observed, one of which corresponded to the glass transition temperature of pure glycerol. This result indicates that at this level of plasticizer there are sufficient glycerol/glycerol interactions occurring to allow a separate glass formation process for glycerol. © 2006 American Chemical Society.

  • 13. Greiner, R.
    et al.
    Alminger, M.L.
    Carlsson, N.-G.
    Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast2001Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 49, nr 5, s. 2228-2233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During food processing such as baking, phytate is dephosphorylated to produce degradation products, such as myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates. Certain myo-inositol phosphates have been proposed to have positive effects on human health. The position of the phosphate groups on the myo-inositol ring is thereby of great significance for their physiological functions. Using a combination of high-performance ion chromatography analysis and kinetic studies the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme from baker's yeast (Saccharomyces cerevisiae) was established. The data demonstrate that the phytate-degrading enzyme from baker's yeast dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2, to finally Ins(2)P (notation 3/4/5/6/1). Knowledge of the absolute stereochemical specificity of the baker's yeast phytase allows use of the enzyme to produce defined myo-inositol phosphates for kinetic and physiological studies.

  • 14. Greiner, R.
    et al.
    Larsson Alminger, M.
    Carlsson, N.-G.
    Muzquiz, M.
    Burbano, C.
    Cuadrado, C.
    Pathway of dephosphorylation of myo-inositol hexakisphosphate by phytases of legume seeds2002Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 50, nr 23, s. 6865-6870Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a combination of high-performance ion chromatography analysis and kinetic studies, the pathway of dephosphorylation of myo-inositol hexakisphosphate by the phytases purified from faba bean and lupine seeds, respectively, was established. The data demonstrate that the legume seed phytases under investigation dephosphorylate myo-inositol hexakisphosphate in a stereospecific way. The phytase from faba bean seeds and the phytase LP2 from lupine seeds degrade phytate by sequential removal of phosphate groups via D-Ins(1,2,3,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, and D-Ins(1,2)P2 to finally Ins(2)P, whereas the phytases LP11 and LP12 from lupine seeds generate the final degradation product Ins(2)P via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, and D-Ins(1,2)P2.

  • 15. Hansson, A.
    et al.
    Giannouli, P.
    Van Ruth, S.
    The influence of gel strength on aroma release from pectin gels in a model mouth and in vivo, monitored with proton-transfer-reaction mass spectrometry2003Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 51, nr 16, s. 4732-4740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The course of events from taking a food into the mouth to the perception of the food's flavor involves many steps, from dilution with saliva, mastication, and transportation of the compounds to the olfactory epithelium to transformation into signals that go to the brain. In addition, there are also the effects of the food's structure and properties. In this study, a proton-transfer-reaction mass spectrometer (PTR-MS) was used to investigate how four pectin-containing systems with different structures and strengths affected the release of aroma compounds in a model mouth and in the nose of an assessor. Both the model mouth and the in-nose measurements showed that the strength and structure of pectin-containing systems are important with regard to the quantity of aroma compounds that are released. Mastication and saliva were also shown to have a large influence on how much of the aroma compound is released from the mouth to the nose.

  • 16. Hansson, A.
    et al.
    Leufven, A.
    Pehrson, K.
    Stenlof, B.
    Multivariate analysis of the influence of pectin, white syrup, and citric acid on aroma concentration in the headspace above pectin gels2002Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 50, nr 13, s. 3803-3809Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pectin gels consist of polysaccharide networks surrounded by water. The gel networks can prevent release of aroma molecules from the gel to the gas phase above. In this study static headspace measurements were performed to correlate aroma concentration in the gas phase above pectin gels to different amounts of the gel ingredients. As a consequence, aroma concentration in the headspace in relation to gel texture, as characterized by rheology measurements, was also studied. Aroma concentration in the headspace above strong gels was low, due to entrapment of aroma molecules within the gel structure. Viscous solutions generally gave a high aroma concentration in the headspace, but owing to a complex matrix, this was lowered when large amounts of the gel ingredients were added. However, a high correlation between interaction terms and square terms of design variables and rheology parameters with aroma compounds indicated nonlinear and complex relationships.

  • 17. Hansson, A.
    et al.
    Leufven, A.
    Van Ruth, S.
    Partition and release of 21 aroma compounds during storage of a pectin gel system2003Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 51, nr 7, s. 2000-2005Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increasing popularity of low-fat products increases the need for a better understanding of how flavor release is affected by partial substitution of fat with hydrocolloids. Partitioning and release of aroma compounds from four pectin gels with different compositions were studied with static headspace and with a model mouth. Air/product partition coefficients determine the potential extent of aroma release, and mass transfer determines the rate at which aroma compounds are released to the vapor phase. This study showed that the gel network had large effects on the partition of aroma compounds between the gel and vapor phase. The specific properties of the aroma compounds were also of importance for the air/gel partition. Storage of the four gels showed that one of the weaker gels was influencing the concentration of aroma compounds in the headspace, probably caused by formation of a denser network over time.

  • 18. Haugen, J.-E.
    et al.
    Undeland, I.
    Lipid oxidation in herring fillets (Clupea harengus) during ice storage measured by a commercial hybrid gas-sensor array system2003Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 51, nr 3, s. 752-759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Volatile compounds released from herring fillets (Clupea harengus) during 15 days of storage on ice have been measured with a commercial hybrid gas-sensor array system. Using partial least-squares regression modeling, the sensor responses were correlated with data from chemical analyses (lipid oxidation products and antioxidants) and sensory analyses (odor). Eight of the 16 sensors proved significant in the correlation studies: 6 metal oxide semiconductor field effect transistor (MOSFET) sensors and 2 Taguchi type sensors. Correlation coefficients for chemical and sensory data ranged from 0.9 to 0.98 and from 0.49 to 0.92, respectively, with 0.92 referring to both "sharp/acrid" and "rancid" odors. Prediction errors ranged from 8 to 14% and from 11 to 25% for the chemical and sensory measures, respectively. That the prediction errors for oxidation product formation (5-9%) were close to the analytical errors of the chemical reference methods indicated close to "optimum" performance of the gas-sensor system. The sensor system predicted the storage time of the herring with a 1-day error. Results illustrate high potential of the gas-sensor technology in rapid nondestructive quality determination of ice-stored herring.

  • 19. Ingemansson, T.
    et al.
    Kaufmann, P.
    Ekstrand, Bo
    SIK – Institutet för livsmedelsforskning.
    Multivariate evaluation of lipid hydrolysis and oxidation data from light and dark muscle of frozen stored rainbow trout (Oncorhynchus mykiss)1995Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 43, nr 8, s. 2046-2052Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lipid hydrolysis and oxidation were evaluated by multivariate statistical methods in farmed rainbow trout (Oncorhynchus mykiss). The trout were acclimatized at 5 or 12°C and then frozen as fillets and stored at -15°C for up to 34 weeks. Results from analyses of lipid hydrolysis and lipid oxidation during frozen storage of light and dark muscle revealed that the major cause of lipid deterioration is hydrolysis. Hydrolysis resulted in an increase in free fatty acids by between 1 and 10%, particularly in the nutritionally important polyunsaturated n-3 fatty acids, 20:5 and 22:6. The phosphatidylcholine content of the muscle decreased by 25-50% during frozen storage. Phosphatidylethanolamine was stable in dark muscle but decreased in light muscle. By multivariate statistical evaluation it was possible to group the samples according to storage time or acclimatization temperature. A lower water temperature (5°C) resulted in reduced lipid stability during frozen storage. © 1995 American Chemical Society.

  • 20. Jacobsson, A.
    et al.
    Nielsen, Tim
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Sjoholm, I.
    Influence of Temperature, Modified Atmosphere Packaging, and Heat Treatment on Aroma Compounds in Broccoli2004Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 52, nr 6, s. 1607-1614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aroma compounds in broccoli stored in different modified atmospheres were studied. The packaging materials used were oriented polypropylene (OPP), poly(vinyl chloride) (PVC), and low-density polyethylene (LDPE) containing an ethylene-absorbing sachet. All samples were stored for either 1 week at a constant temperature of 10 °C or for 3 days at 4 °C, followed by 4 days at 10 °C. The atmospheres that developed inside the packaging materials differed significantly. The broccoli samples were analyzed raw and after cooking, with regard to volatile compounds, using gas-phase (headspace) extraction followed by gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), hexanal, 3-cis-hexen-1-ol, nonanal, ethanol, and a group of thiocyanates were selected for a detailed study because these compounds cause off-odor and can be used as indicators of stress. Significant differences were found in the aroma profiles of the broccoli samples relative to the packaging materials used for storage. Storage in OPP (14% 02, 10.5% CO2) resulted in most of the off-odors, while storage in LDPE (6% 02, 7% CO 2) and PVC (17.9% 02, 4% CO2) was found to maintain the concentration of DMS, DMDS, and DMTS during storage. Heat treatment of the broccoli increased the content of aroma compounds as well as the number of compounds containing sulfur.

  • 21.
    Lingnert, Hans
    et al.
    SIK – Svenska livmedelsinstitutet.
    Akesson, G.
    Eriksson, Caj
    SIK – Svenska livmedelsinstitutet.
    Antioxidative effect of superoxide dismutase from Saccharomyces cerevisiae in model systems1989Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 37, nr 1, s. 23-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Active oxygen species are possible initiators of oxidative reactions in foods, and their elimination could provide one mechanism of antioxidative effect. In this work we studied the antioxidative properties of superoxide dismutase (SOD) from yeast (Saccharomyces cerevisiae) in various model systems. The crude yeast extract was partially purified by ammonium sulfate precipitation. The purified fraction was found to inhibit the oxidation of emulsified linoleic acid, emulsified cholesterol, and ascorbic acid. Catalase had a prooxidative effect in the linoleic acid system, while at high concentrations it protected ascorbic acid against oxidation. No synergistic effect was observed between catalase and SOD. In order to evaluate possible applications of yeast SOD as an antioxidant in food, the influence of pH and heat treatment on the antioxidative effect was studied. Within the range pH 4.5-9.0 the antioxidative effect of the SOD increased with increasing pH. In heat treatment experiments the SOD showed unusually high thermal stability and an interesting inactivation-reactivation behavior. The enzyme activity was for instance retained at about 60% of its original value after heating at 70°C for 15 min. A few percent of the original enzyme activity remained even after 30 min at 100°C. The possible technological implications of these results are discussed. © 1989 American Chemical Society.

  • 22.
    Lingnert, Hans
    et al.
    SIK – Svenska livmedelsinstitutet.
    Waller, G.R.
    Stability of antioxidants formed from histidine and glucose by the Maillard reaction1983Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 31, nr 1;4092, s. 27-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Maillard reaction products (MRP) have been reported by several authors to inhibit lipid oxidation in model systems as well as in food products. The antioxidative compounds formed have so far not been identified, nor has the mechanism of their antioxidative effect been elucidated. In the course of trying to isolate antioxidative components formed by the Maillard reaction between histidine and glucose, it was found that part of the antioxidative effect was lost during the isolation processing. The stability of the antioxidants was therefore studied in more detail. The antioxidants were found to be unstable in solution when exposed to air. When they were stored in nitrogen atmosphere, no loss of antioxidative effect was noticed. The oxygen sensitivity was found to be pH dependent. Within the studied pH range 2-10, the stability of the antioxidants decreased with increasing pH. An oxygen electrode could be used to measure the consumption of oxygen by the MRP. In the dry state and in concentrated solutions at low temperatures, the MRP were found to be fairly stable. The significance of this instability in a food system and in laboratory work with the antioxidants is discussed. © 1983 American Chemical Society.

  • 23. Ma, Hairan
    et al.
    Forssell, Pirkko
    Partanen, Riitta
    Seppänen, Rauni
    YKI – Ytkemiska institutet.
    Buchert, Johanna
    Boer, Harry
    Sodium caseinates with an altered isoelectric point as emulsifiers in oil/water systems2009Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 57, nr 9, s. 3800-3807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sodium caseinate was chemically modified in order to alter its isoelectric point (pI). Negatively charged carboxylic groups were introduced to lower the pI, and positively charged amino groups to achieve the opposite. Different chemical amino acid modification approaches were studied and the modified proteins were characterized using free amino group assays, SDS-PAGE, MALDI-TOF mass spectrometry, and zeta potential measurements. Oil-in-water emulsions were prepared using these modified caseinates. The pH stability behavior of the emulsions was monitored, and interestingly, the stability of the emulsion could be modulated through steering the pI of caseinate. Using different modified caseinates, it was possible to create emulsions that were stable in the acid, neutral, and alkaline regions of the pH spectrum. The stability behavior of the emulsions correlated well with the theoretical and experimentally determined pI values of the caseinates. Storage stability of emulsions was also studied at pH values around 7, and emulsions made of modified caseinates showed storage stability similar to that of unmodified caseinate emulsions.

  • 24. Marmon, S.K.
    et al.
    Krona, Annika
    SIK – Institutet för livsmedel och bioteknik.
    Langton, Maud
    SIK – Institutet för livsmedel och bioteknik.
    Undeland, I.
    Changes in salt solubility and microstructure of proteins from herring (clupea harengus) after pH-shift processing2012Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 60, nr 32, s. 7965-7972Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Salt solubility of pH-shift isolated herring (Clupea harengus) muscle proteins was studied in relation to pH exposure and microstructure using transmission electron microscopy (TEM). Using protein solubilization at pH 11.2 with subsequent precipitation at pH 5.5, salt solubility of the proteins decreased from 78 to 17%. By precipitating the alkali-solubilized proteins at the pH of native herring muscle, 6.5, salt solubility only decreased to 59%, proving that pH values between 6.5 and 5.5 affected protein salt solubility more than the pH cycle 6.5 ? 11.2 ? 6.5. Precipitation at pH 5.5 resulted in hydrogen bonds, hydrophobic interactions, and S-S bridges, whereas precipitation at pH 6.5 resulted only in the formation of hydrophobic interactions. The alkaline pH-shift isolation process severely rearranged the protein microstructure, with precipitation at pH 6.5 forming a finer, more homogeneous network than precipitation at pH 5.5. The former protein isolate also contained less lipid oxidation products and formed more deformable gels, without affecting protein yield. © 2012 American Chemical Society.

  • 25. Newson, W.R.
    et al.
    Kuktaite, R.
    Hedenqvist, M.S.
    Gällstedt, M.
    RISE, Innventia.
    Johansson, E.
    Effect of additives on the tensile performance and protein solubility of industrial oilseed residual based plastics2014Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 62, nr 28, s. 6707-6715Artikkel i tidsskrift (Fagfellevurdert)
  • 26. Persson, H.
    et al.
    Türk, Maria
    SIK – Institutet för livsmedel och bioteknik.
    Nyman, M.
    Sandberg, A.-S.
    Binding of Cu2+, Zn2+, and Cd2+ to Inositol Tri-, Tetra-, Penta-, and Hexaphosphates1998Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 46, nr 8, s. 3194-3200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    myo-Inositol hexaphosphate, the salt of myo-inositol hexaphosphoric acid (IP6), is a common constituent of many plant foods, such as cereals and legumes. IP6 interacts with mineral elements, influencing their bioavailability. Processed foods contain a mixture of different inositol phosphates, i.e., IP6 and its degradation products with five or less phosphate groups (IP5-IP1). The interaction of the lower inositol phosphates with mineral elements is not well-known. In this study, the interaction between metal ions (Cu2+, Zn2+, and Cd2+) and isolated fractions of inositol phosphates with 6, 5, 4 and 3 phosphate groups (IP6-IP3) was investigated by using a potentiometric technique. The study was performed at pH 3-7, which is the pH range in the upper part of the duodenum, where mineral absorption takes place. The inositol phosphate fractions studied had a pronounced binding capacity between pH 5 and 7. Thus, mineral complex formation with lower inositol phosphates is likely to occur in the duodenum, which would be important from a nutritional point of view. The mineral binding capacity as calculated per phosphate group was similar for IP6, IP5, IP4, and IP3, but the binding strength was lower for the lower inositol phosphates (IP4 and IP3). At increasing pH, within the range (pH 3-7), the metal complex formation generally began in the order copper, zinc, cadmium for all inositol phosphates indicating the same order of binding strength, i.e., Cu > Zn > Cd. For IP6 the difference was small between Cu and Zn.

  • 27.
    Pihlsgård, Per
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Larsson, M.
    Leufvén, Anders
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Chemical and sensory properties of liquid beet sugar1999Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 47, nr 10, s. 4346-4352Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sensory analysis and headspace gas chromatography-flame ionization detection (GC-FID) analysis of liquid sugars (sucrose) designated for food- industrial use were performed in order to elucidate which compounds are responsible for perceived off-odors and off-flavors in liquid sugar. The liquid sugar samples investigated had various kinds of off-odors and off- flavors that might influence the quality of any food product in which they might be used, such as a jam or a soft drink. The sensory scores for the different attributes and the levels of different volatile compounds as measured by GC were analyzed for correlation using partial least-squares (PLS) analysis. A link between sensory analysis and GC analysis was thereby established, and compounds critical for the odor and flavor were identified using MS (mass spectrometry). Approximately 10 compounds were found to be correlated with the defined sensory attributes. Among these compounds associated with the sensory attributes were dimethyl disulfide, 2,6- dimethylpyrazine, 4-methoxyphenol, and 2,5-dimethylfuran.

  • 28.
    Pihlsgård, Per
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Larsson, M.
    Leufvén, Anders
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Volatile compounds in the production of liquid beet sugar2000Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 48, nr 10, s. 4844-4850Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Samples from different parts of a beet sugar factory and refinery were analyzed with respect to volatile compounds by means of liquid-liquid extraction followed by gas chromatography-mass spectrometry (GC-MS). A limited number of the samples were analyzed by means of gas phase extraction (headspace) followed by GC-MS. Selected compounds were followed through the sugar manufacturing process. The behavior of different compounds varied greatly throughout the process, with some compounds such as geosmin (trans-1,10-dimethyl-trans-9-decalol), dimethyl disulfide, and propionic and hexanoic acid present at the beginning of the process but disappearing rapidly after further processing. Other compounds, such as indole, dihydrobenzofuran, and 2-phenylethanol, were not detected at the start of the process, but were formed later on and removed in the final product. In the final product, three pyrazines remained at fairly low concentrations, together with 3-methylcyclopentadione, ethylhexanol, and methyl pyrrole ketene.

  • 29.
    Pihlsgård, Per
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Leufvén, Anders
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Aroma compounds in the production of liquid beet sugar2001Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 49, nr 8, s. 3875-3880Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Samples of in-process liquid beet sugar were collected from three different parts of a beet sugar factory and a refinery. The samples were analyzed with respect to aroma compounds by means of both liquid-liquid extraction and gas-phase (headspace) extraction followed by gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (GC-MS). The aromas of the eluted compounds were evaluated qualitatively and quantitatively for the different samples. In general, earthy and sour aromas were often present in the raw juice sample, whereas caramel aromas were mainly present in the samples taken further downstream in the process. For fruity, floral, and solvent-like aromas, different parallel trends were noted. Some aromas were present only at the beginning of the process, whereas others developed toward the end of the process.

  • 30. Qvist, I.H.
    et al.
    von Sydow, Erik
    SIK – Svenska livmedelsinstitutet.
    Unconventional proteins as aroma precursors.: Chemical analysis of the volatile compounds in heated soy, casein, and fish protein model systems1974Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 22, nr 6, s. 1077-1084Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Model samples containing soy, casein, or fish protein were analyzed by gas chromatography and mass spectrometry. The headspace of samples, unheated and heated and with or without fat and starch added, was investigated. Over 150 compounds were identified representing aliphatic hydrocarbons, alcohols, aldehydes, ketones and furan derivatives, and sulfur-containing compounds. The absolute concentrations in the headspace gas were determined for about 80 compounds judged to be of at least potential interest from the aroma point of view. On heating, the concentrations of volatiles generally increase and new compounds are detected. Of particular importance for the aroma of all heated samples is the presence of branched chain aldehydes and sulfur compounds. Moreover, straight chain aldehydes and furans are important in the soy protein samples and hydrogen sulfide in the fish protein sample.

  • 31. Qvist, I.H.
    et al.
    von Sydow, Erik
    SIK – Svenska livmedelsinstitutet.
    Unconventional proteins as aroma precursors.: Chemical analysis of the volatile compounds in unheated and heated rapeseed protein model systems1976Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 24, nr 3, s. 437-442Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Model samples containing rapeseed protein were analyzed by gas chromatography and mass spectrometry. The headspace of samples, unheated and heated, with or without addition of fat and starch, was investigated. Over 100 compounds were identified, representing aliphatic hydrocarbons, alcohols, aldehydes, ketones, nitriles, and furan derivatives, and sulfur-containing compounds. Determinations were made of the absolute concentrations in the headspace gas of about 70 of the compounds judged to be of potential interest from the point of view of aroma. On heating of the samples, the concentrations of volatiles generally increased and new compounds were detected. Of importance for the aroma of the heated samples is the presence of aliphatic aldehydes, sulfur compounds, furans, and probably also nitrogen-containing compounds. © Copyright 1976 by the American Chemical Society.

  • 32. Skoglund, E.
    et al.
    Carlsson, N.-G.
    Sandberg, A.-S.
    Analysis of Inositol Mono- and Diphosphate Isomers Using High-Performance Ion Chromatography and Pulsed Amperometric Detection1997Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 45, nr 12, s. 4668-4673Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A rapid and sensitive high-performance ion chromatography method for separation and quantitative determination of inositol mono- and diphosphate (IP 1-IP 2) isomers using pulsed amperometric detection is described. The method involves extraction of samples with HCl, separation of inositol phosphates from the crude extract by anion-exchange chromatography, NaAc gradient elution in an NaOH environment to perform isomer separation on a high-performance anion-exchange column, and detection with pulsed amperometric detector. The applicability and sensitivity of the method is illustrated by measurement of the content of IP 1 and IP 2 in foods, human ileal contents, and enzymatic hydrolysis products of phytate (inositol hexaphosphate). The major IP 1 and IP 2 isomers formed during phytate hydrolysis with wheat phytase were shown to be Ins(2)P, DL-Ins(1)P, and DL-Ins(1,2)P 2 and with Aspergillus niger phytase, Ins(2)P and DL-Ins(1,2)P 2.

  • 33. Smith, KW
    et al.
    Smith, PR
    YKI – Ytkemiska institutet.
    Furó, I
    Pettersson, TE
    Cain, FW
    Favre, L
    Slow recrystallization of tripalmitoylglycerol from MCT oil observed by 2H NMR2007Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 55, nr 21, s. 8585-8588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystallization and recrystallization of fats have a significant impact on the properties and quality of many food products. While crystallization has been the subject of a number of studies using pure triacylglycerols (TAG), recrystallization in similarly pure systems is rarely studied. In this work, perdeuterated tripalmitoylglycerol (2H-PPP) was dissolved in medium chain triacylglycerol oil (MCT) to yield a saturated solution. The solution was heated to cause partial melting of the solid and dissolution of the molten fraction of 2H-PPP in MCT and was then cooled to the original temperature to induce recrystallization from the supersaturated solution. 2H NMR was used to monitor the disappearance of 2H-PPP from the solution and showed that recrystallization occurred in two steps. The first step was rapid, taking place over a few minutes, and accounted for more than two-thirds of the total recrystallization. The second step was much slower, taking place over a remarkably long timescale of hours to days. It is proposed that dissolution occurs from all parts of the crystals, leaving an etched and pitted surface. The first step of crystallization is the infilling of these pits, while the second step is the continued growth on the smoothed crystal faces.

  • 34.
    Undeland, Ingrid
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Ekstrand, Bo
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Lipid oxidation in minced herring (Clupea harengus) during frozen storage.: Effect of Washing and Precooking1998Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 46, nr 6, s. 2319-2328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 23 factorial experimental design was used to investigate the effect of washing in combination with precooking on the oxidative stability of lipids in minced herring (Clupea harengus) at -18°C. The following variables were studied: washing (no, yes), cooking time (38, 54 min), and cooking temperature (55, 100°C). The responses monitored were peroxide value (PV), absorbance at 234 nm (A234), absorbance at 268 nm (A268), and lipid soluble fluorescent products (FP). A partial least-squares regression analysis (PLS) revealed that the best lipid stability was obtained at minimum cooking time and at lower temperature. On the basis of compositional analyses and in vitro experiments, this finding was proposed to be due to heat inactivation of catalytic enzymes, without simultaneous activation, for example, of hemoproteins. Washing reduced these benefits from precooking by removal of pro-oxidative enzymes and also through a reduction in the amount of antioxidants as well as a relative increase in phospholipids and free fatty acids in the fat.

  • 35.
    Undeland, Ingrid
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Hall, Gunnar
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Lipid oxidation in fillets of herring (Clupea harengus) during ice storage1999Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 47, nr 2, s. 524-532Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of ice storage on lipid oxidation, odor, antioxidants, water-soluble catalysts, and microorganisms was investigated in fillets of herring (Clupea harengus) during 15 days. Based on linear regression analyses of the data, significant rises (p ? 0.05) in lipid oxidation products were seen after 2-3 days and in 'rancid' odor after 2.5 days. Peroxide value (PV), fluorescent product (FP), and ascorbic acid analyses were the chemical measures most strongly correlated to 'rancid' odor (r = 0.97). Antioxidants decreased in the following order: ?-tocopherol > ascorbic acid > glutathione peroxidase (GSH-px); however, GSH-px correlated best to the development of lipid oxidation products (r(mean) = -0.96). The activity of aqueous pro- oxidants, which were enzymatic in nature to a great extent, had decreased by 75% at day 15. No significant increase in total bacteria was seen until after 7 days. There were major local differences in both composition and stability throughout the fillet. Oxidation proceeded most rapidly in the tissue right under the skin, probably explained by its high initial pro-oxidative activity.

  • 36.
    Undeland, Ingrid
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Hall, Gunnar
    SIK – Institutet för livsmedel och bioteknik.
    Wendin, Karin
    SIK – Institutet för livsmedel och bioteknik.
    Gangby, I.
    Rutgersson, A.
    Preventing lipid oxidation during recovery of functional proteins from herring (Clupea harengus) fillets by an acid solubilization process2005Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 53, nr 14, s. 5625-5634Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has previously been found that a process based on solubilization at pH 2.7 gives high yields of herring muscle proteins with good functionality. In this study, the development of lipid oxidation during acid processing of herring mince was studied. It was tested how modifications of the process conditions and/or additions of antioxidants could prevent lipid oxidation during the actual process and then during ice storage of the protein isolates. Processing parameters evaluated were prewash of the mince, exposure time to pH 2.7, inclusion or exclusion of a high-speed centrifugation, and addition of antioxidants. Antioxidants tested were erythorbate (0.2%, 9.3 mM), sodium tripolyphosphate (STPP; 0.2%, 5.4 mM), ethylenediaminetetraacetic acid (EDTA; 0.044%, 1.5 mM), and milk proteins (4%). The first three antioxidants were added in the prewash or during the homogenization step, whereas milk proteins were added to the final precipitate. At time 0, all isolates were analyzed for pH, moisture content, and thiobarbituric reactive substances (TBARS). Selected isolates were also analyzed for lipid and protein content. Stability during ice storage was followed in terms of odor, TBARS, and color (a*/b* values). Extensive lipid oxidation took place using the "control" process without high-speed centrifugation. This was not significantly (p ? 0.05) affected by a prewash or varied exposure time to pH 2.7. Including high-speed centrifugation (20 min, 10000g) significantly (p ? 0.05) reduced TBARS values, total lipids, a* values and b* values. Erythorbate alone, or in combination with STPP/EDTA, significantly (p ? 0.05) reduced lipid oxidation during processing if added in the prewash or homogenization step. During ice storage, better stability was gained when antioxidants were added in both of these steps and when EDTA was used instead of STPP. © 2005 American Chemical Society.

  • 37.
    Undeland, Ingrid
    et al.
    SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    SIK – Institutet för livsmedel och bioteknik.
    Lipid oxidation in fillets of herring (Clupea harengus) during frozen storage. Influence of prefreezing storage1999Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 47, nr 5, s. 2075-2081Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fillets of herring (Clupea harengus) were kept on ice for 0, 3, 6, and 9 days prior to storage at -18 °C for 0, 21, 42, 63, and 84 days. At each storage point, peroxide value (PV), absorbance at 268 nm (A268), fluorescent products (FP), ?-tocopherol, glutathione peroxidase (GSH-px) activity, and ascorbic acid were measured. As shown by regression analyses, samples held for 6 days on ice formed oxidation products at the highest rate during frozen storage, followed by, for PV and FP, the 9-day samples. These data indicate that severe changes that negatively affect the oxidation process took place in the herring muscle between 3 and 6 days after catch. Both the initial antioxidant levels and the rate of antioxidant loss at -18 °C decreased with increased prefreezing holding time, the latter being most obvious for GSH-px activity and ascorbic acid. ?-Tocopherol showed the largest losses and had disappeared entirely from the 6- and 9-day samples at the end of the frozen storage. Partial least-squares regression analysis of the data showed that ice storage had a greater effect than frozen storage on changes in PV, A268, FP, ?-tocopherol, and ascorbic acid. For GSH-px activity, frozen storage had the greatest effect.

  • 38. Zhang, H
    et al.
    Smith, P
    YKI – Ytkemiska institutet.
    Adler-Nissen, J
    Effects of degree of enzymatic interesterification on the physical properties of margarine fats – Solid fat content, crystallization behavior, crystal morphology and crystal network2004Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 52, s. 4423-4431Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study enzymatic-interesterified margarine fats with different conversion degrees were produced in a packed bed reactor. The effects of conversion degree on the formation of free fatty acids and diglycerides, solid fat content, crystallization behavior, microstructure, and crystal network were investigated and the enzymatically interesterified products were compared with a chemically esterified product. Formation of free fatty acids, and diacyglycerols increased slightly with increasing conversion degree. The solid fat content was higher at 10 and 20∞C and lower at 30, 35, and 40∞C with the increasing conversion degree. Addition of 50% of rapeseed oil into the blend and products caused the content of b to decreas from 100 to 33, and 30% and eventually to pure b’ crystal. However, double chain packing was observed both for the blend and products. Isothermal crystallization kinetics was characterized by the Fisher-Turnbull model. Highest free energy was observed for the blend. Small deformation with oscillation tests shows significant difference between the blend and interesterified products. The differences of microstructure between the blend, different conversion degree and chemical randomized product were observed. Lipozyme TL IM, interesterification, packed-bed reactor, crystallization, nuclear magnetic resonance (NMR), DSC, X-ray, and light microscopy.

1 - 38 of 38
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v. 2.35.4