| 1. |
- Anker, M., et al.
(författare)
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Aging of whey protein films and the effect on mechanical and barrier properties
- 2001
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 49:2, s. 989-995
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Anker, M., et al.
(författare)
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Relationship between the microstructure and the mechanical and barrier properties of whey protein films
- 2000
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 48:9, s. 3806-3816
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Bengtsson, M., et al.
(författare)
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Plant odor analysis of apple : Antennal response of codling moth females to apple volatiles during phenological development
- 2001
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 49:8, s. 3736-3741
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Tidskriftsartikel (refereegranskat)abstract
- Volatile compounds were collected from apple branches (Malus domestica) at different developmental stages, and the antennal response of codling moth females (Cydia pomonella) to these compounds was recorded by electroantennography coupled to gas chromatography. Presence of a range of terpenoid compounds, many of which had antennal activity, was characteristic for volatile collections from branches with leaves, and from small green apples. Nine compounds from branches with leaves and green fruit consistently elicited an antennal response: methyl salicylate, (E)-beta -farnesene, fi-caryophyllene, 4,8-dimethyl-1,3(E),7-nonatriene, (Z)3-hexenol, (Z,E)-alpha -farnesene, linalool, germacrene D, and (EE)-alpha -farnesene. The bouquet emitted from flowering branches contained in addition several benzenoid compounds which were not found after bloom. Small green apples, which are the main target of codling moth oviposition during the first seasonal flight period, released very few esters. In comparison, fully grown apples released a large number of esters, but fewer terpenoids. The study of apple volatiles eliciting an antennal response, together with a survey of the seasonal change in the release of these compounds, is the first step toward the identification of volatiles mediating host-finding and oviposition in codling moth females.
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| 4. |
- Bergendorff, Ola, et al.
(författare)
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Spontaneous Formation of Thiuram Disulfides in Solutions of Iron(III) Dithiocarbamates.
- 2002
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 50:5, s. 1092-1096
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Tidskriftsartikel (refereegranskat)abstract
- Dithiocarbamates are used as pesticides and rubber additives. Dithiocarbamates are the reduced forms of thiuram disulfides and both of these groups of substances induce allergic contact dermatitis. The allergic cross-reactivity pattern between dithiocarbamates and thiurams is unclear. The aim of this study was to investigate why these cross-reactions occur sometimes but not always. HPLC-analysis of buffer solutions of iron(III) dithiocarbamates demonstrated that thiuram disulfides were formed spontaneously and rapidly in high yield. No such oxidation was observed in solutions of copper(II), zinc(II), or sodium dithiocarbamates. However, sodium diethyldithiocarbamate and zinc diethyldithiocarbamate were oxidized in buffer solution when ferric salt was added. The influence of different metal ions on the oxidation reaction is probably an explanation for the cross-reactivity patterns seen between dithiocarbamates and thiurams. These findings also show that careful handling is necessary in analytical and biological studies with solutions of iron(III) dithiocarbamates. Oxidation of dithiocarbamates in aqueous buffer at physiological pH has not been shown before.
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| 5. |
- Bratt, Katarina, et al.
(författare)
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Avenanthramides in Oats (Avena Sativa L.) and Structure-Activity Relationships
- 2003
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 51:3, s. 594-600
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Tidskriftsartikel (refereegranskat)abstract
- Eight avenanthramides, amides of anthranilic acid (1) and 5-hydroxyanthranilic acid (2), respectively, and the four cinnamic acids p-coumaric (p), caffeic (c), ferulic (f), and sinapic (s) acid, were synthesized for identification in oat extracts and for structure−antioxidant activity studies. Three compounds (2p, 2c, and 2f) were found in oat extracts. As assessed by the reactivity toward 1,1-diphenyl-2-picrylhydrazyl (DPPH), all avenanthramides except 1p showed activity. Initially, the antioxidant activity of the avenanthramides decreased in a similar order as for the corresponding cinnamic acids, that is: sinapic > caffeic > ferulic > p-coumaric acid. The avenanthramides derived from 2 were usually slightly more active than those derived from 1. All avenanthramides inhibited azo-initiated peroxidation of linoleic acid. 1c and 1s were initially the most effective compounds. The relative order of antioxidant activities was slightly different for the DPPH and the linoleic acid assays run in methanol and chlorobenzene, respectively.
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| 6. |
- Cerecetto, H, et al.
(författare)
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Synthesis and herbicidal activity of N-oxide derivatives
- 2000
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 48:7, s. 2995-3002
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Tidskriftsartikel (refereegranskat)abstract
- As part of an ongoing program on the chemistry and biological activity of N-oxide-containing molecules, a number of novel 1,2,5-oxadiazole N-oxide, benzo[1,2-c]1,2,5-oxadiazole N-oxide, and quinoxaline N,N'-dioxide derivatives were synthesized and evaluated for their herbicidal activity. Many of these compounds exhibited moderate to good herbicidal pre-emergence activity against Triticum aestivum. Dose-response studies were done on the more representative compounds (12, 20, and 26). The most active compound, butylcarbamoylbenzo[1,2-c]l,2,5-oxadiazole N-oxide, 26, displayed herbicidal activity at concentrations as low as 24 g/ha.
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| 7. |
- Creamer, Lawrence K, et al.
(författare)
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Heat-Induced Redistribution of Disulfide Bonds in Milk Proteins. 1. Bovine beta-Lactoglobulin
- 2004
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 52:25, s. 7660-7668
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the structure and chemistry of -lactoglobulin (-LG) play an important role in the processing and functionality of milk products. In model -LG systems, there is evidence that the aggregates of heated -LG are held together by a mixture of intermolecular non-covalent association and heat-induced non-native disulfide bonds. Although a number of non-native disulfide bonds have been identified, little is known about the initial inter- and intramolecular disulfide bond rearrangements that occur as a result of heating. These interchange reactions were explored by examining the products of heat treatment to determine the novel disulfide bonds that form in the heated -LG aggregates. The native protein and heat-induced aggregates were hydrolyzed by trypsin, and the resulting peptides, before and after reduction with dithiothreitol, were separated by high-performance liquid chromatography and their identities confirmed by electrospray ionization mass spectrometry. Comparisons of these peptide patterns showed that some of the Cys160 was in the reduced form in heated -LG aggregates, indicating that the Cys160-Cys66 disulfide bond had been broken during heating. This finding suggests that disulfide bond interchange reactions between -LG non-native monomers, or polymers, and other proteins could occur largely via Cys160.
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| 8. |
- Ehn, B.-M., et al.
(författare)
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Modification of IgE Binding during Heat Processing of the Cow's Milk Allergen ?-Lactoglobulin
- 2004
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 52:5, s. 1398-1403
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Fredrikson, Mattias, 1969, et al.
(författare)
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Production process for high-quality pea-protein isolate with low content of oligosaccharides and phytate
- 2001
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 49:3, s. 1208-1212
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Tidskriftsartikel (refereegranskat)abstract
- A process for pea-protein isolate production, resulting in low content of phytate and oligosaccharides, has been developed. Oligosaccharides were removed from the protein fraction through ultrafiltration. Ultrafiltration of 50- and 100-kD molecular-weight cutoffs (MWCOs) were tested, and both effectively separated the oligosaccharides from the protein. Phytate degradation was achieved by incubation of the pea-protein solution by addition of exogenous phytase enzyme. An almost complete degradation of inositol hexa-, penta-, tetra-, and triphosphates was reached using an incubation time of 1 h. The reduced content of oligosaccharides and inositol phosphates is likely to result in reduced flatulence and improved mineral bioavailability. These qualities of the pea-protein isolate make it a suitable protein source for infant formula production.
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| 10. |
- Greiner, R., et al.
(författare)
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Pathway of dephosphorylation of myo-inositol hexakisphosphate by phytases of legume seeds
- 2002
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 50:23, s. 6865-6870
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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